Beam mask and sliding window-facilitated deep learning-based accurate and efficient dose prediction for pencil beam scanning proton therapy

BACKGROUND

Accurate and efficient dose calculation is essential for on-line adaptive planning in proton therapy. Deep learning (DL) has shown promising dose prediction results in photon therapy. However, there is a scarcity of DL-based dose prediction methods specifically designed for proton therapy. Successful dose prediction method for proton therapy should account for more challenging dose prediction problems in pencil beam scanning proton therapy (PBSPT) due to its sensitivity to heterogeneities.

PURPOSE

To develop a DL-based PBSPT dose prediction workflow with high accuracy and balanced complexity to support on-line adaptive proton therapy clinical decision and subsequent replanning.

METHODS

PBSPT plans of 103 prostate cancer patients (93 for training and the other 10 for independent testing) and 83 lung cancer patients (73 for training and the other 10 for independent testing) previously treated at our institution were included in the study, each with computed tomography scans (CTs), structure sets, and plan doses calculated by the in-house developed Monte-Carlo dose engine (considered as the ground truth in the model training and testing). For the ablation study, we designed three experiments corresponding to the following three methods: (1) Experiment 1, the conventional region of interest (ROI) (composed of targets and organs-at-risk [OARs]) method. (2) Experiment 2, the beam mask (generated by raytracing of proton beams) method to improve proton dose prediction. (3) Experiment 3, the sliding window method for the model to focus on local details to further improve proton dose prediction. A fully connected 3D-Unet was adopted as the backbone. Dose volume histogram (DVH) indices, 3D Gamma passing rates with a criterion of 3%/3 mm/10%, and dice coefficients for the structures enclosed by the iso-dose lines between the predicted and the ground truth doses were used as the evaluation metrics. The calculation time for each proton dose prediction was recorded to evaluate the method's efficiency.

RESULTS

Compared to the conventional ROI method, the beam mask method improved the agreement of DVH indices for both targets and OARs and the sliding window method further improved the agreement of the DVH indices (for lung cancer, CTV D98 absolute deviation: 0.74 ± 0.18 vs. 0.57 ± 0.21 vs. 0.54 ± 0.15 Gy[RBE], ROI vs. beam mask vs. sliding window methods, respectively). For the 3D Gamma passing rates in the target, OARs, and BODY (outside target and OARs), the beam mask method improved the passing rates in these regions and the sliding window method further improved them (for prostate cancer, targets: 96.93% ± 0.53% vs. 98.88% ± 0.49% vs. 99.97% ± 0.07%, BODY: 86.88% ± 0.74% vs. 93.21% ± 0.56% vs. 95.17% ± 0.59%). A similar trend was also observed for the dice coefficients. This trend was especially remarkable for relatively low prescription isodose lines (for lung cancer, 10% isodose line dice: 0.871 ± 0.027 vs. 0.911 ± 0.023 vs. 0.927 ± 0.017). The dose predictions for all the testing cases were completed within 0.25 s.

CONCLUSIONS

An accurate and efficient deep learning-augmented proton dose prediction framework has been developed for PBSPT, which can predict accurate dose distributions not only inside but also outside ROI efficiently. The framework can potentially further reduce the initial planning and adaptive replanning workload in PBSPT.

Sublobar Resection, Stereotactic Body Radiation Therapy, and Percutaneous Ablation Provide Comparable Outcomes for Lung Metastasis-Directed Therapy

BACKGROUND

Prolonged survival of patients with metastatic disease has furthered interest in metastasis-directed therapy (MDT).

RESEARCH QUESTION

There is a paucity of data comparing lung MDT modalities. Do outcomes among sublobar resection (SLR), stereotactic body radiation therapy (SBRT), and percutaneous ablation (PA) for lung metastases vary in terms of local control and survival?.

STUDY DESIGN AND METHODS

Medical records of patients undergoing lung MDT at a single cancer center between January 2015 and December 2020 were reviewed. Overall survival (OS), local progression (LP), and toxicity outcomes were collected. Patient and lesion characteristics were used to generate multivariable models with propensity weighted analysis.

RESULTS

Lung MDT courses (644 total: 243 SLR, 274 SBRT, 127 PA) delivered to 511 patients were included with a median follow-up of 22 months. There were 47 LP events in 45 patients, and 159 patients died. Two-year OS and LP were 80.3% and 63.3%, 83.8% and 9.6%, and 4.1% and 11.7% for SLR, SBRT, and PA, respectively. Lesion size per 1 cm was associated with worse OS (hazard ratio [HR], 1.24; P = .003) and LP (HR, 1.50; P < .001). There was no difference in OS by modality. Relative to SLR, there was no difference in risk of LP with PA; however, SBRT was associated with a decreased risk (HR, 0.26; P = .023). Rates of severe toxicity were low (2.1%-2.6%) and not different among groups.

INTERPRETATION

This study performs a propensity weighted analysis of SLR, SBRT, and PA and shows no impact of lung MDT modality on OS. Given excellent local control across MDT options, a multidisciplinary approach is beneficial for patient triage and longitudinal management.

Deep-learning based fast and accurate 3D CT deformable image registration in lung cancer

BACKGROUND

Deformable Image Registration (DIR) is an essential technique required in many applications of radiation oncology. However, conventional DIR approaches typically take several minutes to register one pair of 3D CT images and the resulting deformable vector fields (DVFs) are only specific to the pair of images used, making it less appealing for clinical application.

PURPOSE

A deep-learning-based DIR method using CT images is proposed for lung cancer patients to address the common drawbacks of the conventional DIR approaches and in turn can accelerate the speed of related applications, such as contour propagation, dose deformation, adaptive radiotherapy (ART), etc. METHODS: A deep neural network based on VoxelMorph was developed to generate DVFs using CT images collected from 114 lung cancer patients. Two models were trained with the weighted mean absolute error (wMAE) loss and structural similarity index matrix (SSIM) loss (optional) (i.e., the MAE model and the M+S model). In total, 192 pairs of initial CT (iCT) and verification CT (vCT) were included as a training dataset and the other independent 10 pairs of CTs were included as a testing dataset. The vCTs usually were taken 2 weeks after the iCTs. The synthetic CTs (sCTs) were generated by warping the vCTs according to the DVFs generated by the pre-trained model. The image quality of the synthetic CTs was evaluated by measuring the similarity between the iCTs and the sCTs generated by the proposed methods and the conventional DIR approaches, respectively. Per-voxel absolute CT-number-difference volume histogram (CDVH) and MAE were used as the evaluation metrics. The time to generate the sCTs was also recorded and compared quantitatively. Contours were propagated using the derived DVFs and evaluated with SSIM. Forward dose calculations were done on the sCTs and the corresponding iCTs. Dose volume histograms (DVHs) were generated based on dose distributions on both iCTs and sCTs generated by two models, respectively. The clinically relevant DVH indices were derived for comparison. The resulted dose distributions were also compared using 3D Gamma analysis with thresholds of 3 mm/3%/10% and 2 mm/2%/10%, respectively.

RESULTS

The two models (wMAE and M+S) achieved a speed of 263.7±163 / 265.8±190 ms and a MAE of 13.15±3.8 / 17.52±5.8 HU for the testing dataset, respectively. The average SSIM scores of 0.987±0.006 and 0.988±0.004 were achieved by the two proposed models, respectively. For both models, CDVH of a typical patient showed that less than 5% of the voxels had a per-voxel absolute CT-number-difference larger than 55 HU. The dose distribution calculated based on a typical sCT showed differences of ≤2cGy[RBE] for clinical target volume (CTV) D95 and D5 , within ±0.06% for total lung V5 , ≤1.5cGy[RBE] for heart and esophagus Dmean , and ≤6cGy[RBE] for cord Dmax compared to the dose distribution calculated based on the iCT. The good average 3D Gamma passing rates (> 96% for 3 mm/3%/10% and > 94% for 2 mm/2%/10%, respectively) were also observed.

CONCLUSION

A deep neural network-based DIR approach was proposed and has been shown to be reasonably accurate and efficient to register the initial CTs and verification CTs in lung cancer.

Improving Dose Volume Histogram (DVH) Based Analysis of Clinical Outcomes Using Modern Statistical Techniques: A Systematic Answer to Multiple Comparisons Concerns

PURPOSE/OBJECTIVE(S)

DVH constraints are essential in the clinical practice of radiation therapy. Historically, DVH constraints were found through sparse sampling of all possible DVH indices to find one that appeared to be most predictive for clinical toxicity. This approach can lead to inconsistent results among studies and to multiple comparison concerns. We aim to solve both problems by examining a full array of DVH indices using statistical methods that account for strong correlations among DVH indices and incorporate radiobiological knowledge constraints.

MATERIALS/METHODS

We extracted a dense array of V%_D indices from a treatment planning system using ESAPI interface, with V%_D corresponding to the volume fraction irradiated to dose D, or higher. We used Fused Lasso as the base model to compensate for correlations among DVH indices because it applies a penalty on the difference between DVH variables with adjacent dose. The base model was augmented with additional constraints based on radiobiological considerations: the positivity constraint (beta_i > 0) which assumes that any tissue irradiation cannot reduce the risk of toxicity, and monotonicity constraint (beta_i+1 > = beta_i) which assumes that higher dose to a fixed volume fraction cannot be associated with a lower risk of toxicity. We called the hybrid model KC-Lasso (Knowledge Constrained Lasso) and applied it to two clinical examples: grade 2 acute rectal toxicity in conventionally fractionated RT for 79 prostate cancer patients (77.4 Gy + MR based boost to 81-83 Gy) and cardiac toxicity in conventionally fractionated RT for 119 locally advanced Non-small Cell Lung Cancer (NSCLC) patients (Median prescribed dose 62 Gy). We further examined alternative data driven models to determine the importance of knowledge constraints.

RESULTS

KC-Lasso detected two distinct dose thresholds for grade 2 rectal toxicity, at 35 Gy and 78 Gy. A threshold of 51 Gy was detected for reduced overall survival due to cardiac irradiation in NSCLC patients. An examination of KC-Lasso models at varying step size suggested that a single mid-range index can be used as a treatment planning constraint while full model can be used for confirmatory, final plan evaluation. Alternative models which lack knowledge constraints show patterns of negative and isolated coefficients which are difficult to interpret and are not likely to be generalizable.

CONCLUSION

A more systematic approach to the analysis of correlations between DVH constraints and clinical toxicity can lead to greater consistency of results among different studies, better understanding of true dose thresholds and results which are more generalizable.

Radiotherapy for Metastatic Spinal Cord Compression with Increased Doses: Final Results of the RAMSES-01 Trial

PURPOSE/OBJECTIVE(S)

To investigate the outcomes of precision-radiotherapy (RT) with 15 × 2.633 Gy (EQD2 = 41.6 Gy for tumor cell kill, α/β = 10 Gy) or 18 × 2.333 Gy (EQD2 = 43.2 Gy) in patients with metastatic spinal cord compression (MSCC) and favorable survival prognoses (>35 points on a validated survival score). In addition, these patients were compared to a historical control group of patients with favorable prognoses treated with 10 × 3 Gy (EQD2 = 32.5 Gy).

MATERIALS/METHODS

In a multi-center phase 2 study (RAMSES-01), patients with MSCC and favorable survival prognoses receiving 15 × 2.633 Gy or 18 × 2.333 Gy of precision-RT alone (no upfront surgery) were mainly evaluated for local progression-free survival (LPFS), defined as no deterioration of motor function during RT and no in-field recurrence of MSCC following RT, at 12 months (primary endpoint). Secondary endpoints included improvement of motor and sensory functions, post-RT ambulatory status, relief of pain and distress, toxicity, and survival (OS). The maximum relative doses allowed to the spinal cord were 101.5 % of the prescribed dose for 18 × 2.333 Gy and 101.2% for 15 × 2.633 Gy, respectively (both representing an EQD2 of 46.6 Gy for myelopathy, α/β = 2 Gy). In addition, the RAMSES-cohort was compared to a historical control group (N = 266) irradiated with 10 × 3 Gy (propensity score adjusted Cox regression).

RESULTS

In the RAMSES-cohort, 50 (of 62 planned) patients were evaluable for LPFS and included in the analyses. Since OS was worse than expected, a new survival score was developed, which was more precise in predicting OS than a previous tool. As a consequence, the RAMSES-trial, which was based on the previous score, was terminated. In the 50 patients included so far, 12-month rates of LPFS and OS were 97.6% and 69.9%, respectively. Improvement of motor function occurred in 28 patients (56.0%), and 47 patients (94.0%) were ambulatory following RT. Within 3 months following RT, 12 of 21 patients (57.2%) with pre-RT sensory deficits improved, 38 of 45 patients (84.4%) with pre-RT pain experienced at least partial relief, and 39 of 50 patients (78.0%) reported relief of distress. Ten of 50 patients (20.0%) experienced grade 2 toxicities (mainly esophagitis/dysphagia) and another two patients (4.0%) grade 3 toxicities (1 diarrhea, 1 esophagitis). After propensity score adjustment, the RAMSES-cohort showed significantly better LPFS than the control group (hazard ratio = 0.125, 95% confidence interval = 0.016 - 0.962, p = 0.046) and a strong trend regarding improvement of motor function (hazard ratio = 1.943, 95% confidence interval = 0.981 - 3.850, p = 0.057). Post-RT ambulatory rates (p = 0.56) and OS rates (p = 0.62) were not significantly different.

CONCLUSION

Precision-RT with 15 × 2.633 Gy or 18 × 2.333 Gy was sufficiently well tolerated and resulted in significantly better long-term LPFS than 10 × 3 Gy in patients with MSCC and favorable survival prognoses. Thus, the dose-fractionation regimens of the RAMSES-01 trial appear preferable for these patients.

Oncologic Outcomes of Conventionally Fractionated, Hypofractionated, and Stereotactic Body Spot-Scanned Proton Radiation Therapy for Prostate Cancer: The Mayo Clinic Experience

PURPOSE/OBJECTIVE(S)

Spot/pencil beam scanned proton therapy is a relatively new technology with fundamental differences from double scattered or IMRT. We aimed to report the long-term oncologic outcomes of a contemporary prospective series of patients treated with spot-scanned proton therapy (SSPT).

MATERIALS/METHODS

An IRB-approved prospective registry identified patients with prostate cancer treated with proton therapy between January 2016 and December 2018. Descriptive statistics were calculated for all patients. Clinical, demographic, and treatment characteristics were gathered and analyzed. Kaplan-Meier curves were generated to estimate survival and recurrence rates. Outcomes assessed included 5-year overall survival (OS), 5-year local control (LC), biochemical failure (BF), regional and distant failures, and physician-reported adverse events (AEs). Biochemical failure was defined as rise in PSA ≥ 2.0 ng/mL above nadir PSA. Acute and chronic gastrointestinal (GI) and genitourinary (GU) grade 2+ and grade 3+ baseline-adjusted AEs were assigned using CTCAE v5.0. All failures were re-staged with PET C-11 or PSMA.

RESULTS

With a median follow up of 4.4 years (IQR 3.7 - 5), two hundred and eighty-six prostate cancer patients with a median age of 72 (IQR 67.5 - 77) were treated with spot-scanned proton radiation. The median Gleason grade group was 3 (IQR 2 - 4). The median pre-RT PSA was 6.9 ng/mL (IQR 4.3 - 10.5). Median T-stage was T1c. Nearly 64% of all patients were on androgen deprivation therapy at the time of initiating radiation treatment. The median total radiation dose was 79.2 Gy delivered over 44 fractions, 70 Gy over 28 fractions, and 38 Gy over 5 fractions for CF, HF, and SBRT regimens, respectively. The BF rate for all patients was 8.4%. The 5-year LC rates for CF, HF, and SBRT were 100% (95% CI: 100 - 100), 100% (95% CI: 100 - 100), and 97.3% (95% CI: 92.2 - 100), respectively (p = 0.07). Regional recurrences occurred in 12 (4.2%) patients: 8 (5.6%) treated with CF, 2 (2.1%) with HF, and 2 (4.3%) with SBRT (p = 0.62). Distant metastatic failures occurred in 12 patients (4.2%): 5 (3.5%) treated with CF, 7 (7.4%) with HF, and none with SBRT (0%) (p = 0.052). The 5-year OS for patients treated with CF, HF, and SBRT SSPT were 88.2% (95% CI: 81.8 - 95), 86.2% (95% CI: 77.6 - 95.6), and 97.2% (95% CI: 92 - 100), respectively (p = 0.1). Acute and chronic grade 2+ GI baseline-adjusted AEs occurred in 8 (2.8%) and 51 (17.8%) patients, respectively. Acute and chronic grade 3+ GI baseline-adjusted AEs occurred in 3 (1%) and 4 (1.4%) patients, respectively. Acute and chronic grade 2+ GU-related AEs were observed in 72 (25.2%) and 63 (22%) patients, respectively. Acute and chronic grade 3+ GU toxicity was observed in 3 (1%) and 6 (2.1%) patients, respectively.

CONCLUSION

Spot-scanned proton radiation therapy provides high local control rates and excellent oncologic outcomes across different fractionation schedules with low long-term AE rates.

Incremental retraining, clinical implementation, and acceptance rate of deep learning auto-segmentation for male pelvis in a multiuser environment

BACKGROUND

Deep learning auto-segmentation (DLAS) models have been adopted in the clinic; however, they suffer from performance deterioration owing to the clinical practice variability. Some commercial DLAS software provide an incremental retraining function that enables users to train a custom model using their institutional data to account for clinical practice variability.

PURPOSE

This study was performed to evaluate and implement the commercial DLAS software with the incremental retraining function for definitive treatment of patients with prostate cancer in a multi-user environment.

METHODS

CT-based target organs and organs-at-risk (OAR) delineation of 215 prostate cancer patients were utilized. The performance of three commercial DLAS software built-in models was validated with 20 patients. A retrained custom model was developed using 100 patients and evaluated on the remaining data (n = 115). Dice similarity coefficient (DSC), Hausdorff distance (HD), mean surface distance (MSD), and surface DSC (SDSC) were utilized for quantitative evaluation. A multi-rater qualitative evaluation was blindly performed with a five-level scale. Visual inspection was performed in consensus and non-consensus unacceptable cases to identify the failure modes.

RESULTS

Three commercial DLAS vendor built-in models achieved sub-optimal performance in 20 patients. The retrained custom model had a mean DSC of 0.82 for prostate, 0.48 for seminal vesicles (SV), and 0.92 for rectum, respectively. This represents a significant improvement over the built-in model with DSC of 0.73, 0.37, and 0.81 for the corresponding structures. Compared to the acceptance rate of 96.5% and consensus unacceptable rate (i.e., both reviewers rated as unacceptable) of 3.5% achieved by manual contours, the custom model achieved a 91.3% acceptance rate and 8.7% consensus unacceptable rate. The failure modes of retrained custom model were attributed to the following: cystogram (n = 2), hip prosthesis (n = 2), low dose rate brachytherapy seeds (n = 2), air in endorectal balloon(n = 1), non-iodinated spacer (n = 2), and giant bladder(n = 1).

CONCLUSION

The commercial DLAS software with the incremental retraining function was validated and clinically adopted for prostate patients in a multi-user environment. AI-based auto-delineation of the prostate and OARs is shown to achieve improved physician acceptance, overall clinical utility, and accuracy.

Beam mask and sliding window-facilitated deep learning-based accurate and efficient dose prediction for pencil beam scanning proton therapy

PURPOSE

To develop a DL-based PBSPT dose prediction workflow with high accuracy and balanced complexity to support on-line adaptive proton therapy clinical decision and subsequent replanning.

METHODS

PBSPT plans of 103 prostate cancer patients and 83 lung cancer patients previously treated at our institution were included in the study, each with CTs, structure sets, and plan doses calculated by the in-house developed Monte-Carlo dose engine. For the ablation study, we designed three experiments corresponding to the following three methods: 1) Experiment 1, the conventional region of interest (ROI) method. 2) Experiment 2, the beam mask (generated by raytracing of proton beams) method to improve proton dose prediction. 3) Experiment 3, the sliding window method for the model to focus on local details to further improve proton dose prediction. A fully connected 3D-Unet was adopted as the backbone. Dose volume histogram (DVH) indices, 3D Gamma passing rates, and dice coefficients for the structures enclosed by the iso-dose lines between the predicted and the ground truth doses were used as the evaluation metrics. The calculation time for each proton dose prediction was recorded to evaluate the method's efficiency.

RESULTS

Compared to the conventional ROI method, the beam mask method improved the agreement of DVH indices for both targets and OARs and the sliding window method further improved the agreement of the DVH indices. For the 3D Gamma passing rates in the target, OARs, and BODY (outside target and OARs), the beam mask method can improve the passing rates in these regions and the sliding window method further improved them. A similar trend was also observed for the dice coefficients. In fact, this trend was especially remarkable for relatively low prescription isodose lines. The dose predictions for all the testing cases were completed within 0.25s.

Deep-Learning-based Fast and Accurate 3D CT Deformable Image Registration in Lung Cancer

PURPOSE

In some proton therapy facilities, patient alignment relies on two 2D orthogonal kV images, taken at fixed, oblique angles, as no 3D on-the-bed imaging is available. The visibility of the tumor in kV images is limited since the patient's 3D anatomy is projected onto a 2D plane, especially when the tumor is behind high-density structures such as bones. This can lead to large patient setup errors. A solution is to reconstruct the 3D CT image from the kV images obtained at the treatment isocenter in the treatment position.

METHODS

An asymmetric autoencoder-like network built with vision-transformer blocks was developed. The data was collected from 1 head and neck patient: 2 orthogonal kV images (1024x1024 voxels), 1 3D CT with padding (512x512x512) acquired from the in-room CT-on-rails before kVs were taken and 2 digitally-reconstructed-radiograph (DRR) images (512x512) based on the CT. We resampled kV images every 8 voxels and DRR and CT every 4 voxels, thus formed a dataset consisting of 262,144 samples, in which the images have a dimension of 128 for each direction. In training, both kV and DRR images were utilized, and the encoder was encouraged to learn the jointed feature map from both kV and DRR images. In testing, only independent kV images were used. The full-size synthetic CT (sCT) was achieved by concatenating the sCTs generated by the model according to their spatial information. The image quality of the synthetic CT (sCT) was evaluated using mean absolute error (MAE) and per-voxel-absolute-CT-number-difference volume histogram (CDVH).

RESULTS

The model achieved a speed of 2.1s and a MAE of <40HU. The CDVH showed that <5% of the voxels had a per-voxel-absolute-CT-number-difference larger than 185 HU.

CONCLUSION

A patient-specific vision-transformer-based network was developed and shown to be accurate and efficient to reconstruct 3D CT images from kV images.

NCCN Guidelines® Insights: Non-Small Cell Lung Cancer, Version 2.2023

The NCCN Guidelines for Non-Small Cell Lung Cancer (NSCLC) provide recommendations for management of disease in patients with NSCLC. These NCCN Guidelines Insights focus on neoadjuvant and adjuvant (also known as perioperative) systemic therapy options for eligible patients with resectable NSCLC.

Personalization of Radiation Therapy in the Primary Treatment of Malignant Epidural Spinal Cord Compression (MESCC)

"True" malignant epidural spinal cord compression (MESCC) is used here to describe a lesion compressing of infiltrating the spinal cord associated with neurologic deficits. Radiotherapy alone is the most common treatment, for which several dose-fractionation regimens are available including single-fraction, short-course and longer-course regimens. Since these regimens are similarly effective regarding functional outcomes, patients with poor survival are optimally treated with short-course or even single-fraction radiotherapy. Longer-course radiotherapy results in better local control of malignant epidural spinal cord compression. Since most in-field recurrences occur 6 months or later, local control is particularly important for longer-term survivors who, therefore, should receive longer-course radiotherapy. It is important to estimate survival prior to treatment, which is facilitated by scoring tools. Radiotherapy should be supplemented by corticosteroids, if safely possible. Bisphosphonates and RANK-ligand inhibitors may improve local control. Selected patients can benefit from upfront decompressive surgery. Identification of these patients is facilitated by prognostic instruments considering degree of compression, myelopathy, radio-sensitivity, spinal stability, post-treatment ambulatory status, and patients' performance status and survival prognoses. Many factors including patients' preferences must be considered when designing personalized treatment regimens.

Clinical Outcomes of Stereotactic Radiosurgery-Related Radiation Necrosis in Patients with Intracranial Metastasis from Melanoma

Background:

Radiation necrosis (RN) is a clinically relevant complication of stereotactic radiosurgery (SRS) for intracranial metastasis (ICM) treatments. Radiation necrosis development is variable following SRS. It remains unclear if risk factors for and clinical outcomes following RN may be different for melanoma patients. We reviewed patients with ICM from metastatic melanoma to understand the potential impact of RN in this patient population.

Methods:

Patients who received SRS for ICM from melanoma at Mayo Clinic Arizona between 2013 and 2018 were retrospectively reviewed. Data collected included demographics, tumor characteristics, radiation parameters, prior surgical and systemic treatments, and patient outcomes. Radiation necrosis was diagnosed by clinical evaluation including brain magnetic resonance imaging (MRI) and, in some cases, tissue evaluation.

Results:

Radiation necrosis was diagnosed in 7 (27%) of 26 patients at 1.6 to 38 months following initial SRS. Almost 92% of all patients received systemic therapy and 35% had surgical resection prior to SRS. Patients with RN trended toward having larger ICM and a prior history of surgical resection, although statistical significance was not reached. Among patients with resection, those who developed RN had a longer period between surgery and SRS start (mean 44 vs 33 days). Clinical improvement following treatment for RN was noted in 2 (29%) patients.

Conclusions:

Radiation necrosis is relatively common following SRS for treatment of ICM from metastatic melanoma and clinical outcomes are poor. Further studies aimed at mitigating RN development and identifying novel approaches for treatment are warranted.

Short Communication: Results of a Consensus Conference on Radiotherapy for Brain and Bone Metastases Within the Interreg-Project TreaT

BACKGROUND/AIM

Differences between radiotherapy for metastases in Northern Germany and Southern Denmark were previously identified, which led to a consensus conference.

PATIENTS AND METHODS

A consensus conference was held between three centers to harmonize radiotherapy regimens for bone and brain metastases.

RESULTS

Centers agreed on 1×8 Gy for painful bone metastases in patients with poor or intermediate survival prognoses and 10×3 Gy for favorable-prognosis patients. For complicated bone metastases, 5-6×4 Gy was preferred for poor-prognosis, 10×3 Gy for intermediate-prognosis, and longer-course radiotherapy for favorable-prognosis patients. For ≥5 brain metastases, centers agreed on whole-brain irradiation (WBI) with 5×4 Gy in poor-prognosis and longer-course regimens in other patients. For single brain lesions and patients with 2-4 lesions and intermediate/favorable prognoses, fractionated stereotactic radiotherapy (FSRT) or radiosurgery were recommended. No consensus was reached for 2-4 lesions in poor-prognosis patients; two centers preferred FSRT, one center WBI. Preferred radiotherapy regimens were similar for different age groups including elderly and very elderly patients, but age-specific survival scores were recommended.

CONCLUSION

The consensus conference was successful, since harmonization of radiotherapy regimens was achieved for 32 of 33 possible situations.

Comparison of Two Cisplatin Regimens for Chemoradiation in Patients With Squamous-cell Carcinoma of the Head and Neck

BACKGROUND/AIM

Many patients with squamous-cell carcinoma of the head and neck receive cisplatin-based chemoradiation. This retrospective study compared two chemoradiation programs to help identify the optimal cisplatin-regimen.

PATIENTS AND METHODS

Forty-one patients assigned to chemoradiation with two cycles of 20 mg/m²/days(d)1-5 were compared to 78 patients assigned to chemoradiation with two cycles of 25 mg/m²/d1-4. Groups were compared for toxicity, loco-regional control (LRC), and survival.

RESULTS

Both treatments were associated with similar rates of oral mucositis, radiation dermatitis, xerostomia, nausea, decreased renal function, and hematotoxicity. The cisplatin-regimen had no significant impact on LRC (p=0.41) or survival (p=0.85). Survival was significantly worse with radiotherapy interruptions (>1 week) or discontinuation (p<0.001) and administration of <80% of the planned cisplatin dose (p<0.001).

CONCLUSION

Both cisplatin-regimens did not differ significantly regarding toxicities, LRC, and survival. It is important to avoid interruption or discontinuation of radiotherapy and to administer ≥80% of planned cisplatin.

Evaluation of the Impact of Smoking and Alcohol Consumption on Toxicity and Outcomes of Chemoradiation for Head and Neck Cancer

BACKGROUND/AIM

Smoking and alcohol abuse may impair outcomes of chemoradiation for squamous cell head and neck cancer (SCCHN). Potential associations with toxicity, loco-regional control (LRC), and overall survival (OS) were investigated.

PATIENTS AND METHODS

Ninety-six patients were retrospectively analyzed for impacts of pre-radiotherapy (pre-RT) smoking history, smoking during radiotherapy, and pre-RT alcohol abuse on toxicity, LRC, and OS.

RESULTS

A trend was found for associations between pre-RT smoking history and grade ≥2 dermatitis. Smoking during radiotherapy was significantly associated with grade ≥3 mucositis and showed trends regarding grade ≥2 mucositis and dermatitis. On univariate analyses, smoking during radiotherapy was negatively associated with LRC and OS, pre-RT alcohol abuse with OS, and >40 pack years with LRC and OS. In multivariate analyses, smoking during radiotherapy remained significant for decreased OS, and pack years showed a trend.

CONCLUSION

Smoking during radiotherapy was an independent predictor of OS and associated with increased toxicity. Thus, it is important to stop smoking prior to the start of radiotherapy.

Comparison of Three Survival Scores in a Series of Patients ≥80 Years of Age Irradiated for Bone Metastases

BACKGROUND/AIM

Very elderly patients irradiated for bone metastases likely benefit from individualized treatments. A specific survival score was created for this group and compared to existing instruments.

PATIENTS AND METHODS

Ninety-six patients aged 80+ irradiated for bone metastases were retrospectively evaluated. Dose-fractionation regimen plus twelve characteristics were evaluated for survival.

RESULTS

In the Cox regression model, performance status and tumor type were significant and used for the score, which included three groups (5-7, 8-12, and 14 points) with 6-month survival rates of 15%, 52%, and 90%. Positive predictive values (PPVs) regarding death ≤6 months were 85% (new score), 100% (previous 65+ score), and 84% (previous score for any age). The new instrument and the 65+ score were also very accurate regarding survival. Since PPV regarding death was calculated from only four patients for the 65+ score, this PPV may be less conclusive than that for the new instrument.

CONCLUSION

The new score appears useful for patients aged 80+ irradiated for bone metastases.

Prognostic factors in resected pulmonary carcinoid tumors: A retrospective study with 10 years of follow‑up

The objective of the present study was to characterize the difference in 10-year carcinoid-specific survival (CSS) and disease-free survival (DFS) among patients with resected pulmonary typical carcinoid (TC) and atypical carcinoid (AC). Patients diagnosed with pulmonary carcinoid tumors (PCT) between January 1, 1997, and December 31, 2016, were identified. All patients underwent video-assisted thoracoscopic surgery or thoracotomy with thoracic lymphadenectomy. Cumulative CSS was estimated using the Kaplan-Meier model. The analysis of hazard ratios (HRs) and 95% confidence intervals (CIs) was performed using univariate and multivariate Cox proportional hazards models. A total of 404 patients with PCT were included in the present study. The 10-year CSS and DFS rates of patients with AC were significantly worse than those of patients with TC (49.1 vs. 86.8% and 52.2 vs. 92.6%, respectively; P<0.001). In the CSS multivariate analysis, older age and lymph node involvement (HR, 2.45; P=0.022) were associated with worse survival in AC, while age, male sex, M1 stage, cigarette smoking and inadequate N2 lymphadenectomy were associate with worse survival in TC. In the recurrence multivariate analysis, N1-3 stage (HR, 2.62; 95% CI, 1.16-5.95; P=0.018) and inadequate N2 lymphadenectomy (HR, 2.13; 95% CI, 1.04-4.39; P=0.041) were associated with an increase in recurrence in AC, while male sex (HR, 3.72; 95% CI, 1.33-10.42; P=0.010) and M1 stage (HR, 14.93; 95% CI, 4.77-46.77; P<0.001) were associated with an increase in recurrence in TC. In conclusion, patients with AC tumors had significantly worse CSS and DFS rates compared with patients with TC. The degree of nodal involvement in AC was a prognostic marker, in contrast to that in TC. Inadequate lymphadenectomy increased the risk of recurrence in AC and mortality in TC, although surgical approaches did not have a significant impact. The present study therefore emphasizes the importance of mediastinal nodal dissection in patients with PCTs.

Early Identification of Pneumonitis in Patients Irradiated for Lung Cancer-Final Results of the PARALUC Trial

Radiotherapy of lung cancer may cause pneumonitis that generally occurs weeks or months following therapy and can be missed. This prospective trial aimed to pave the way for a mobile application (app) allowing early diagnosis of pneumonitis. The primary goal was the identification of the optimal cut-off of a score to detect pneumonitis of grade ≥2 after radiotherapy for lung cancer. Based on the severity of symptoms (cough, dyspnea, fever), scoring points were 0−9. Receiver operating characteristic (ROC)-curves were used to describe the sensitivity and specificity. The area under the ROC-curve (AUC) was calculated to judge the accuracy of the score, Youden-index was employed to define the optimal cut-off. Until trial termination, 57 of 98 patients were included. Eight of 42 patients evaluable for the primary endpoint (presence or absence of radiation pneumonitis) experienced pneumonitis. AUC was 0.987 (0.961−1.000). The highest sensitivity was achieved with 0−4 points (100%), followed by 5 points (87.5%), highest specificity with 5−6 points (100%). The highest Youden-index was found for 5 points (87.5%). The rate of patient satisfaction with the symptom-based scoring system was 93.5%. A cut-off of 5 points was identified as optimal to differentiate between pneumonitis and no pneumonitis. Moreover, pneumonitis was significantly associated with an increase of ≥3 points from baseline (p < 0.0001). The scoring system provided excellent accuracy and high patient satisfaction. Important foundations for the development of a mobile application were laid.

Clinical Practice Evolvement for Post-Operative Prostate Cancer Radiotherapy-Part 2: Feasibility of Margin Reduction for Fractionated Radiation Treatment with Advanced Image Guidance

Purpose: Planning target volume (PTV) expansion for post-prostatectomy radiotherapy is typically ≥5 mm. Recent clinical trials have proved the feasibility of a reduced margin of 2−3 mm for treatments on MRI-linac. We aim to study the minimum PTV margin needed using iterative cone-beam CT (iCBCT) as image guidance on conventional linacs. Materials/Methods: Fourteen patients who received post-prostatectomy irradiation (8 with an endorectal balloon and 6 without a balloon) were included in this study. Treatment was delivered with volumetric modulated radiation therapy (VMAT). Fractional dose delivery was evaluated in 165 treatment fractions. The bladder, rectal wall, femoral heads, and prostate bed clinical tumor volume (CTV) were contoured and verified on daily iCBCT. PTV margins (0 mm, 2 mm, and 4 mm) were evaluated on daily iCBCT. CTV coverage and OAR dose parameters were assessed with each PTV margin. Results: CTV D100% was underdosed with a 0 mm margin in 32% of fractions in comparison with 2 mm (6%) and 4 mm (6%) PTV margin (p ≤ 0.001). CTV D95% > 95% was met in 93−94% fractions for all PTV expansions. CTV D95% > 95% was achieved in more patients with an endorectal balloon than those without: 0 mm—90/91 (99%) vs. 63/74 (85%); 2 mm—90/91 (99%) vs. 65/75 (87%); 4 mm—90/90 (100%) vs. 63/73 (86%). There was no difference in absolute median change in CTV D95% (0.32%) for 0-, 2-, and 4 mm margins. The maximum dose remained under 108% for 100% (0 mm), 97% (2 mm), and 98% (4 mm) of images. Rectal wall maximum dose remained under 108% for 100% (0 mm), 100% (2 mm), and 98% (4 mm) of images. Conclusions: With high-quality iCBCT image guidance, PTV margin accounting for inter-fractional uncertainties can be safely reduced for post-prostatectomy radiotherapy. For fractionated radiotherapy, an isotropic expansion of 2 mm and 4 mm may be considered for margin expansion with and without the endorectal balloon. Future application for margin reduction needs to be further evaluated and considered with the advent of shorter post-prostatectomy radiation courses.

Clinical Practice Evolvement for Post-Operative Prostate Cancer Radiotherapy-Part 1: Consistent Organs at Risk Management with Advanced Image Guidance

Purpose: Post-operative prostate cancer patients are treated with full bladder instruction and the use of an endorectal balloon (ERB). We reassessed the efficacy of this practice based on daily image guidance and dose delivery using high-quality iterative reconstructed cone-beam CT (iCBCT). Methods: Fractional dose delivery was calculated on daily iCBCT for 314 fractions from 14 post-operative prostate patients (8 with and 6 without ERB) treated with volumetric modulated radiotherapy (VMAT). All patients were positioned using novel iCBCT during image guidance. The bladder, rectal wall, femoral heads, and prostate bed clinical tumor volume (CTV) were contoured and verified on daily iCBCT. The dose-volume parameters of the contoured organs at risk (OAR) and CTV coverage were assessed for the clinical impact of daily bladder volume variations and the use of ERB. Minimum bladder volume was studied, and a straightforward bladder instruction was explored for easy clinical adoption. Results: A “minimum bladder” contour, the overlap between the original bladder contour and a 15 mm anterior and superior expansion from prostate bed PTV, was confirmed to be effective in identifying cases that might fail a bladder constraint of V65% <60%. The average difference between the maximum and minimum bladder volumes for each patient was 277.1 mL. The daily bladder volumes varied from 62.4 to 590.7 mL and ranged from 29 to 286% of the corresponding planning bladder volume. The bladder constraint of V65% <60% was met in almost all fractions (98%). CTVs (D90%, D95%, and D98%) remained well-covered regardless of the absolute bladder volume daily variation or the presence of the endorectal balloon. Patients with an endorectal balloon showed smaller variation but a higher average maximum rectal wall dose (D0.03mL: 104.3% of the prescription) compared to patients without (103.3%). Conclusions: A “minimum bladder” contour was determined that can be easily generated and followed to ensure sufficient bladder sparing. Further analysis and validation are needed to confirm the utility of the minimal bladder contour. Accurate dose delivery can be achieved for prostate bed target coverage and OAR sparing with or without the use of ERB.

Preliminary Analysis of a Phase II Trial of Stereotactic Body Radiation Therapy for Prostate Cancer With High-Risk Features After Radical Prostatectomy

Purpose

There are limited data regarding using stereotactic body radiation therapy (SBRT) in the postprostatectomy setting. Here, we present a preliminary analysis of a prospective phase II trial that aimed to evaluate the safety and efficacy of postprostatectomy SBRT for adjuvant or early salvage therapy.

Materials and Methods

Between May 2018 and May 2020, 41 patients fulfilled inclusion criteria and were stratified into 3 groups: group I (adjuvant), prostate-specific antigen (PSA) < 0.2 ng/mL with high-risk features including positive surgical margins, seminal vesicle invasion, or extracapsular extension; group II (salvage), with PSA ≥ 0.2 ng/mL but < 2 ng/mL; or group III (oligometastatic), with PSA ≥ 0.2 ng/mL but < 2 ng/mL and up to 3 sites of nodal or bone metastases. Androgen deprivation therapy was not offered to group I. Androgen deprivation therapy was offered for 6 months for group II and 18 months for group III patients. SBRT dose to the prostate bed was 30 to 32 Gy in 5 fractions. Baseline-adjusted physician reported toxicities (Common Terminology Criteria for Adverse Events), patient reported quality-of-life (Expanded Prostate Index Composite, Patient-Reported Outcome Measurement Information System), and American Urologic Association scores were evaluated for all patients.

Results

The median follow-up was 23 months (range, 10-37). SBRT was adjuvant in 8 (20%) patients, salvage in 28 (68%), and salvage with the presence of oligometastases in 5 (12%) patients. Urinary, bowel, and sexual quality of life domains remained high after SBRT. Patients tolerated SBRT with no grade 3 or higher (3+) gastrointestinal or genitourinary toxicities. The baseline adjusted acute and late toxicity grade 2 genitourinary (urinary incontinence) rate was 2.4% (1/41) and 12.2% (5/41). At 2 years, clinical disease control was 95%, and biochemical control was 73%. Among the 2 clinical failures, 1 was a regional node and the other a bone metastasis. Oligometastatic sites were salvaged successfully with SBRT. There were no in-target failures.

Conclusions

Postprostatectomy SBRT was very well tolerated in this prospective cohort, with no significant effect on quality of life metrics postirradiation, while providing excellent clinical disease control.

Technical note: Investigation of dose and LETd effect to rectum and bladder by using non-straight laterals in prostate cancer receiving proton therapy

BACKGROUND

Parallel-opposed lateral beams are the conventional beam arrangements in proton therapy for prostate cancer. However, when considering linear energy transfer (LET) and RBE effects, alternative beam arrangements should be investigated.

PURPOSE

To investigate the dose and dose averaged LET (LET_d ) impact of using new beam arrangements rotating beams 5°-15° posteriorly to the laterals in prostate cancer treated with pencil-beam-scanning (PBS) proton therapy.

METHODS

Twenty patients with localized prostate cancer were included in this study. Four proton treatment plans for each patient were generated utilizing 0°, 5°, 10°, and 15° posterior oblique beam pairs relative to parallel-opposed lateral beams. Dose-volume histograms (DVHs) from posterior oblique beams were analyzed. Dose-LET_d -volume histogram (DLVH) was employed to study the difference in dose and LET_d with each beam arrangement. DLVH indices, V ( d , l ) $V( {d,l} )$ , defined as the cumulative absolute volume that has a dose of at least d (Gy[RBE]) and a LET_d of at least l (keV/µm), were calculated for both the rectum and bladder to the whole group of patients and two-sub groups with and without hydrogel spacer. These metrics were tested using Wilcoxon signed-rank test.

RESULTS

Rotating beam angles from laterals to slightly posterior by 5°-15° reduced high LET_d volumes while it increased the dose volume in the rectum and increased LET_d in bladders. Beam angles rotated five degrees posteriorly from laterals (i.e., gantry in 95° and 265°) are proposed since they achieved the optimal balance of better LET_d sparing and minimal dose increase in the rectum. A reduction of V(50 Gy[RBE], 2.6 keV/µm) from 7.41 to 3.96 cc (p < 0.01), and a slight increase of V(50 Gy[RBE], 0 keV/µm) from 20.1 to 21.6 cc (p < 0.01) were observed for the group without hydrogel spacer. The LET_d sparing was less effective for the group with hydrogel spacer, which achieved the reduction of V(50 Gy[RBE], 2.6 keV/µm) from 4.28 to 2.10 cc (p < 0.01).

CONCLUSIONS

Posterior oblique angle plans improved LET_d sparing of the rectum while sacrificing LET_d sparing in the bladder in the treatment of prostate cancer with PBS. Beam angle modification from laterals to slightly posterior may be a strategy to redistribute LET_d and perhaps reduce rectal toxicity risks in prostate cancer patients treated with PBS. However, the effect is reduced for patients with hydrogel spacer.

Cardiopulmonary Toxicity Following Intensity-Modulated Proton Therapy (IMPT) Versus Intensity-Modulated Radiation Therapy (IMRT) for Stage III Non-Small Cell Lung Cancer

INTRODUCTION

Intensity-modulated proton therapy (IMPT) has the potential to reduce radiation dose to normal organs when compared to intensity-modulated radiation therapy (IMRT). We hypothesized that IMPT is associated with a reduced rate of cardiopulmonary toxicities in patients with Stage III NSCLC when compared with IMRT.

METHODS

We analyzed 163 consecutively treated patients with biopsy-proven, stage III NSCLC who received IMPT (n = 35, 21%) or IMRT (n = 128, 79%). Patient, tumor, and treatment characteristics were analyzed. Overall survival (OS), freedom-from distant metastasis (FFDM), freedom-from locoregional relapse (FFLR), and cardiopulmonary toxicities (CTCAE v5.0) were calculated using the Kaplan-Meier estimate. Univariate cox regressions were conducted for the final model.

RESULTS

Median follow-up of surviving patients was 25.5 (range, 4.6-58.1) months. Median RT dose was 60 (range, 45-72) Gy [RBE]. OS, FFDM, and FFLR were not different based on RT modality. IMPT provided significant dosimetric pulmonary and cardiac sparing when compared to IMRT. IMPT was associated with a reduced rate of grade more than or equal to 3 pneumonitis (HR 0.25, P = .04) and grade more than or equal to 3 cardiac events (HR 0.33, P = .08). Pre-treatment predicted diffusing capacity for carbon monoxide less than equal to 57% (HR 2.8, P = .04) and forced expiratory volume in the first second less than equal to 61% (HR 3.1, P = .03) were associated with an increased rate of grade more than or equal to 3 pneumonitis.

CONCLUSIONS

IMPT is associated with a reduced risk of clinically significant pneumonitis and cardiac events when compared with IMRT without compromising tumor control in stage III NSCLC. IMPT may provide a safer treatment option, particularly for high-risk patients with poor pretreatment pulmonary function.

Virtual particle Monte Carlo: A new concept to avoid simulating secondary particles in proton therapy dose calculation

BACKGROUND

In proton therapy dose calculation, Monte Carlo (MC) simulations are superior in accuracy but more time consuming, compared to analytical calculations. Graphic processing units (GPUs) are effective in accelerating MC simulations but may suffer thread divergence and racing condition in GPU threads that degrades the computing performance due to the generation of secondary particles during nuclear reactions.

PURPOSE

A novel concept of virtual particle (VP) MC (VPMC) is proposed to avoid simulating secondary particles in GPU-accelerated proton MC dose calculation and take full advantage of the computing power of GPU.

METHODS

Neutrons and gamma rays were ignored as escaping from the human body; doses of electrons, heavy ions, and nuclear fragments were locally deposited; the tracks of deuterons were converted into tracks of protons. These particles, together with primary and secondary protons, are considered to be the realistic particles. Histories of primary and secondary protons were replaced by histories of multiple VPs. Each VP corresponded to one proton (either primary or secondary). A continuous-slowing-down-approximation model, an ionization model, and a large angle scattering event model corresponding to nuclear interactions were developed for VPs by generating probability distribution functions (PDFs) based on simulation results of realistic particles using MCsquare. For efficient calculations, these PDFs were stored in the Compute Unified Device Architecture textures. VPMC was benchmarked with TOPAS and MCsquare in phantoms and with MCsquare in 13 representative patient geometries. Comparisons between the VPMC calculated dose and dose measured in water during patient-specific quality assurance (PSQA) of the selected 13 patients were also carried out. Gamma analysis was used to compare the doses derived from different methods and calculation efficiencies were also compared.

RESULTS

Integrated depth dose and lateral dose profiles in both homogeneous and inhomogeneous phantoms all matched well among VPMC, TOPAS, and MCsquare calculations. The 3D-3D gamma passing rates with a criterion of 2%/2 mm and a threshold of 10% was 98.49% between MCsquare and TOPAS and 98.31% between VPMC and TOPAS in homogeneous phantoms, and 99.18% between MCsquare and TOPAS and 98.49% between VPMC and TOPAS in inhomogeneous phantoms, respectively. In patient geometries, the 3D-3D gamma passing rates with 2%/2 mm/10% between dose distributions from VPMC and MCsquare were 98.56 ± 1.09% in patient geometries. The 2D-3D gamma analysis with 3%/2 mm/10% between the VPMC calculated dose distributions and the 2D measured planar dose distributions during PSQA was 98.91 ± 0.88%. VPMC calculation was highly efficient and took 2.84 ± 2.44 s to finish for the selected 13 patients running on four NVIDIA Ampere GPUs in patient geometries.

CONCLUSION

VPMC was found to achieve high accuracy and efficiency in proton therapy dose calculation.

The First Survival Score for Patients Aged ≥80 Years Irradiated for Brain Metastases

Survival scores facilitate personalized cancer treatment. Due to demographic changes, very elderly patients are more prevalent than in the past. A score was developed in 94 patients aged ≥ 80 years undergoing whole-brain radiotherapy for brain metastases. Dose fractionation, treatment period, age, sex, performance score (ECOG-PS), tumor type, count of lesions, metastases outside the brain, and interval tumor diagnosis to radiotherapy were retrospectively evaluated. Independent predictors of survival were used for the score. Based on individual scoring points obtained from 3-month survival rates, prognostic groups were designed. Additionally, the score was compared to an existing tool developed in patients ≥ 65 years. ECOG-PS, count of lesions, and extra-cranial metastases were independent prognostic factors. Three groups were created (7, 10, and 13−16 points) with 3-month survival of 6%, 25%, and 67% (p < 0.001), respectively. Positive predictive values (PPVs) regarding death ≤ 3 and survival ≥ 3 months were 94% and 67% (new score) vs. 96% and 48% (existing tool), respectively. PPVs for survival ≥1 and ≥2 months were 88% and 79% vs. 63% and 58%, respectively. Both tools were accurate in predicting death ≤2, ≤3, and ≤6 months. The new score was more precise regarding death ≤1 month and survival (all time periods) and appeared preferable. However, it still needs to be validated.

A New Survival Score for Patients ≥65 Years Assigned to Radiotherapy of Bone Metastases

Survival scores are important for personalized treatment of bone metastases. Elderly patients are considered a separate group. Therefore, a specific score was developed for these patients. Elderly patients (≥65 years) irradiated for bone metastases were randomly assigned to the test (n = 174) or validation (n = 174) cohorts. Thirteen factors were retrospectively analyzed for survival. Factors showing significance (p < 0.05) or a trend (p < 0.06) in the multivariate analysis were used for the score. Based on 6-month survival rates, prognostic groups were formed. The score was compared to an existing tool developed in patients of any age. In the multivariate analysis, performance score, tumor type, and visceral metastases showed significance and gender was a trend. Three groups were designed (17, 18−25 and 27−28 points) with 6-month survival rates of 0%, 51%, and 100%. In the validation cohort, these rates were 9%, 55%, and 86%. Comparisons of prognostic groups between both cohorts did not reveal significant differences. In the test cohort, positive predictive values regarding death ≤6 and survival ≥6 months were 100% with the new score vs. 80% and 88% with the existing tool. The new score was more accurate demonstrating the importance of specific scores for elderly patients.

Impact of a mobile application (reminder app) on acute toxicity during radiotherapy of head-and-neck cancer – results of a randomized phase III trial (RAREST-02)

Background

Radiotherapy of head-and-neck cancer (SCCHN) is often associated with acute toxicity. In a previous trial, daily reminders by staff members to perform skin care resulted in less dermatitis. This randomized trial investigated whether a mobile application can replace these reminders.

Methods

Patients were stratified according to tumor site, treatment and center. Fifty-three patients were eligible for per-protocol-set (25 with, 28 without app). Primary endpoint was grade ≥ 2 dermatitis until 60 Gy. Secondary endpoints included dermatitis grade ≥ 2 until end of radiotherapy (EOT), dermatitis grade ≥ 3, and mucositis grade ≥ 2 and ≥ 3.

Results

After an interim analysis, the study was terminated (delayed and slow accrual). Until 60 Gy, grade ≥ 2 dermatitis rates were 72% with vs. 82% without app (p = 0.38), grade ≥ 3 dermatitis rates 20% vs. 11% (p = 0.45). Until EOT, grade ≥ 2 and ≥ 3 dermatitis rates were 72% vs. 86% (p = 0.22) and 24% vs. 18% (p = 0.58). Until 60 Gy, grade ≥ 2 and ≥ 3 mucositis rates were 76% vs. 82% (p = 0.58) and 20% vs. 36% (p = 0.20). Until EOT, corresponding mucositis rates were 76% vs. 82% (p = 0.58) and 28% vs. 43% (p = 0.26).

Conclusion

Given the limitations of this trial, the reminder app led to non-significant reduction of grade ≥ 2 dermatitis, grade ≥ 2 mucositis and ≥ 3 mucositis. Additional studies are required to define the value of reminder apps during radiotherapy for SCCHN.

Identifying patients with malignant spinal cord compression (MSCC) near end of life who can benefit from palliative radiotherapy

BACKGROUND

A previous score predicted death ≤ 2 months following radiotherapy for MSCC. For patients with a high probability of early death, best supportive care was recommended. However, some of these patients may benefit from radiotherapy regarding preservation or improvement of motor function. To identify these patients, an additional score was developed.

METHODS

Pre-treatment factors plus radiotherapy regimen were retrospectively evaluated for successful treatment (improved motor function or remaining ambulatory without aid) and post-treatment ambulatory status in 545 patients who died ≤ 2 months. Factors included age, interval from tumor diagnosis until MSCC, visceral metastases, further bone metastases, primary tumor type, sex, time developing motor deficits, pre-treatment ambulatory status, and number of affected vertebrae. Factors significant on both multivariable analyses were included in the score (worse outcomes 0 points, better outcomes 1 point).

RESULTS

On multivariable analyses, myeloma/lymphoma, time developing motor deficits > 14 days, and pre-treatment ambulatory status were significantly associated with both successful treatment and ambulatory status, affection of 1-2 vertebrae with successful treatment only. On univariable analyses, 1 × 8 and 5 × 4 Gy were not inferior to 5 × 5 Gy and longer-course regimens. Considering the three factors significant for both endpoints, three groups were designed (0, 1, 2-3 points) with treatment success rates of 4%, 15% and 39%, respectively (p < 0.0001), and post-treatment ambulatory rates of 4%, 43% and 86%, respectively (p < 0.0001).

CONCLUSION

This score helps identify patients with MSCC who appear to benefit from palliative radiotherapy in terms of improved motor function or remaining ambulatory in spite of being near end of life.

Long-term outcomes of prostate intensity-modulated radiation therapy incorporating a simultaneous intra-prostatic MRI-directed boost

Purpose/objectives

This retrospective study demonstrates the long-term outcomes of treating prostate cancer using intensity modulated (IMRT) with incorporation of MRI-directed boost.

Materials/methods

From February 2009 to February 2013, 78 men received image-guided IMRT delivering 77.4 Gy in 44 fractions with simultaneously integrated boost to 81–83 Gy to an MRI-identified lesion. Patients with intermediate-risk or high-risk prostate cancer were recommended to receive 6 and 24–36 months of adjuvant hormonal therapy, respectively.

Results

Median follow-up was 113 months (11–147). There were 18 low-risk, 43 intermediate-risk, and 17 high-risk patients per NCCN risk stratification included in this study. Adjuvant hormonal therapy was utilized in 32 patients (41%). The 10-year biochemical control rate for all patients was 77%. The 10-year biochemical control rates for low-risk, intermediate-risk, and high-risk diseases were 94%, 81%, and 88%, respectively (p = 0.35). The 10-year rates of local control, distant control, and survival were 99%, 88%, and 66%, respectively. Of 25 patients who died, only four (5%) died of prostate cancer. On univariate analysis, T-category and pretreatment PSA level were associated with distant failure rate (p = 0.02). There was no grade =3 genitourinary and gastrointestinal toxicities that persisted at the last follow-up.

Conclusions

This study demonstrated the long-term efficacy of using MRI to define an intra-prostatic lesion for SIB to 81–83Gy while treating the entire prostate gland to 77.4 Gy with IMRT. Our study confirms that modern MRI can be used to locally intensify dose to prostate tumors providing high long-term disease control while maintaining favorable long-term toxicity.

A New Clinical Instrument for Estimating the Ambulatory Status after Irradiation for Malignant Spinal Cord Compression

Simple Summary

Since 2005, upfront surgery has been increasingly used in addition to radiotherapy for patients with malignant spinal cord compression (MSCC). As spinal surgery includes significant risks, careful patient selection is crucial. Individual risks and benefits should be considered when choosing an optimal treatment strategy. Benefits include preserving or regaining a patient’s ambulatory function. To facilitate the decision pro or contra upfront surgery, a new prognostic score was developed to predict ambulatory status after radiotherapy alone. This clinical score was created from data of patients previously treated in prospective trials. It includes three prognostic groups (17–21, 22–31, and 32–37 points) with post-radiotherapy ambulatory rates of 10%, 65%, and 97%, respectively. Patients of the 32–37 points group may not require upfront surgery. The new instrument achieved very high accuracy in predicting post-radiotherapy ambulatory and non-ambulatory status and was more precise than a previous prognostic score in predicting non-ambulatory status.

Abstract

Estimating post-treatment ambulatory status can improve treatment personalization of patients irradiated for malignant spinal cord compression (MSCC). A new clinical score was developed from data of 283 patients treated with radiotherapy alone in prospective trials. Radiotherapy regimen, age, gender, tumor type, interval from tumor diagnosis to MSCC, number of affected vertebrae, other bone metastases, visceral metastases, time developing motor deficits, ambulatory status, performance score, sensory deficits, and sphincter dysfunction were evaluated. For factors with prognostic relevance in the multivariable logistic regression model after backward stepwise variable selection, scoring points were calculated (post-radiotherapy ambulatory rate in % divided by 10) and added for each patient. Four factors (primary tumor type, sensory deficits, sphincter dysfunction, ambulatory status) were used for the instrument that includes three prognostic groups (17–21, 22–31, and 32–37 points). Post-radiotherapy ambulatory rates were 10%, 65%, and 97%, respectively, and 2-year local control rates were 100%, 75%, and 88%, respectively. Positive predictive values to predict ambulatory and non-ambulatory status were 97% and 90% using the new score, and 98% and 79% using the previous instrument. The new score appeared more precise in predicting non-ambulatory status. Since patients with 32–37 points had high post-radiotherapy ambulatory and local control rates, they may not require surgery.

Exploratory study of seed spots analysis to characterize dose and linear energy transfer effect in adverse event initialization of pencil beam scanning proton therapy

BACKGROUND

Both dose and linear-energy-transfer (LET) could play a substantial role in adverse event (AE) initialization of cancer patients treated with pencil-beam-scanning proton therapy (PBS). However, not all the voxels within the AE regions are directly induced from the dose and LET effect. It is important to study the synergistic effect of dose and LET in AE initialization by only including a subset of voxels that are dosimetrically important.

PURPOSE

To perform exploratory investigation of the dose and LET effects upon AE initialization in PBS using seed spots analysis.

METHODS

113 head and neck (H&N) cancer patients receiving curative PBS were included. Among them, 20 patients experienced unanticipated CTCAEv4.0 grade≥3 AEs (AE group) and 93 patients did not (control group). Within the AE group, 13 AE patients were included in the seed spot analysis to derive the descriptive features of AE initialization and the remaining 7 mandible osteoradionecrosis patients and 93 control patients were used to derive the feature-based volume constraint of mandible osteoradionecrosis. The AE regions were contoured and the corresponding dose-LET volume histograms (DLVHs) of AE regions were generated for all patients in the AE group. We selected high LET voxels (the highest 5% of each dose bin) with a range of moderate to high dose (≥∼40 Gy[RBE]) as critical voxels. Critical voxels which were contiguous with each other were grouped into clusters. Each cluster was considered as a potential independent seed spot for AE initialization. Seed spots were displayed in a 2D dose-LET plane based on their mean dose and LET to derive the descriptive features of AE initialization. A volume constraint of mandible osteoradionecrosis was then established based on the extracted features using a receiver operating characteristic curve.

RESULTS

The product of dose and LET (xBD) was found to be a descriptive feature of seed spots leading to AE initialization in this preliminary study. The derived xBD volume constraint for mandible osteoradionecrosis showed good performance with an area-under-curve of 0.87 (sensitivity of 0.714 and specificity of 0.807 in the leave-one-out cross validation) for the very limited patient data included in this study.

CONCLUSION

Our exploratory study showed that both dose and LET were observed to be important in AE initializations. The derived xBD volume constraint could predict mandible osteoradionecrosis reasonably well in the very limited H&N cancer patient data treated with PBS included in this study. This article is protected by copyright. All rights reserved.

Toxicity and outcomes after external beam irradiation for prostate cancer in patients with prior holmium laser enucleation of the prostate: Early experience

PURPOSE/OBJECTIVES

Holmium laser enucleation of the prostate (HoLEP) is commonly performed in patients with significant bladder outlet obstruction. However, there are few reports on the toxicity of external beam irradiation (RT) for prostate cancer in patients after prior HoLEP. In this study, we evaluate the side effects and treatment outcomes of RT after HoLEP.

MATERIALS/METHODS

Eighteen patients who had HoLEP and subsequently received RT for prostate cancer were included. Data collected included patient and disease characteristics, urinary function, and radiation dose. Acute and late urinary (GU) and gastrointestinal (GI) side effects were evaluated. Disease control and survival rates were calculated using Kaplan-Meier method.

RESULTS

Median follow-up was 18 months (range: 4-46 months). Median prostate volume was 107 ml before HoLEP and 24 ml after HoLEP. Median International Prostate Symptom Score (IPSS) was 17 (range: 5-32) before HoLEP. Median decline in IPSS score after HoLEP was 7 (range: -2-21). On uroflow study, peak flow rate, and post-void residual were significantly improved after HoLEP. After radiation, peak flow rate and average flow rate showed a decline but remained significantly improved compared to pre-HoLEP measurements. Maximum acute Common Terminology Criteria for Adverse Events (CTCAE) adverse events were 12 grade 1 and 3 grade 2 for GU, and 3 grade 1 for GI, respectively. Maximum late adverse events were 13 grade 1 and 2 grade 2 for GU, and all grade 0 for GI, respectively. At last follow-up, there were 8 grade 1 and 1 grade 2 late GU, and 3 grade 1 late GI adverse events, respectively. There was no significant increase in urinary incontinence after RT compared to before RT. The 18-month biochemical control, local control, distant control rates were 78%, 94%, and 80%, respectively.

CONCLUSIONS

Patients who received RT as definitive treatment for prostate cancer after prior HoLEP had low risk of serious acute and late side effects. HoLEP can be safely performed and should be considered in patients with significant bladder outlet obstruction and large prostate volume before RT.

A New and Easy-to-Use Survival Score for Patients Irradiated for Metastatic Epidural Spinal Cord Compression

PURPOSE

A survival score was created in 2008 to improve treatment personalization of patients irradiated for metastatic epidural spinal cord compression (MESCC). Since then, targeted therapies improved survival of patients with cancer, which may decrease this score's predictive value. A new score appears necessary.

METHODS AND MATERIALS

Two hundred sixty-four patients receiving radiation therapy without surgery in prospective trials (2010-2021) were included. A dose-fractionation regimen plus 15 factors were analyzed: age, sex, tumor type, interval tumor diagnosis to MESCC, MESCC sites, affected vertebrae, additional bone lesions, other distant lesions (yes or no), number of organs involved by metastases, time developing motor deficits, ambulatory status, sensory function, sphincter dysfunction, pain, and distress. Six-month survival rates (%) of independent prognostic factors were divided by 10 and summed for each patient. The score was compared with the previous tool for predicting death ≤6 months and survival ≥6 months.

RESULTS

In a multivariate analysis, tumor type (P = .001), other distant lesions (P < .001), and ambulatory status (P < .001) were significant. Based on 6-month survival rates, 4 groups (8-9, 10-13, 14-17, and 18 points) were created with 6-month survival rates of 12.8%, 34.7%, 62.8%, and 90.0%, respectively (version A). For version B, "other distant lesions" was replaced by "number of organs involved by metastases." Version B included 4 groups (8-10, 11-14, 15-16, and 17 points) with 6-month survival rates of 11.1%, 42.0%, 68.6%, and 91.7%, respectively. Positive predictive values to predict death ≤6 months were 87.2% (version A) and 88.9% (version B) versus 76.6% (3 groups) and 84.6% (5 groups) for the previous score. Positive predictive values to predict survival ≥6 months were 90.0% and 91.7% versus 59.0% and 64.3%.

CONCLUSIONS

Both versions of the new score were more precise than the previous tool. Version B appears slightly superior to version A but requires more extensive diagnostic staging that may not be readily available when emergently treating.

Impact of Dose-Volume Parameters of Parotid Glands on Xerostomia in Patients Irradiated for Head-and-Neck Cancer

BACKGROUND/AIM

Optimal planning of radiotherapy for head-and-neck cancers should consider the risk of xerostomia. This study investigated the prognostic value of dosevolume parameters of the parotid glands.

PATIENTS AND METHODS

Dose-volume parameters were evaluated for xerostomia in 145 patients including D40 (minimum dose to 40% of corresponding parotid volume), D60 (minimum dose to 60%), D80 (minimum dose to 80%), and mean dose of ipsilateral, contralateral, and bilateral parotid glands.

RESULTS

Grade ≥2 xerostomia was significantly associated with D40 of ipsilateral and all parameters of bilateral glands; trends were found for all other parameters. Grade ≥3 xerostomia was significantly associated with D80 of bilateral glands; trends were found for other parameters of ipsilateral and bilateral glands.

CONCLUSION

Since grade ≥2 xerostomia was associated with all parameters, D40, D60, and D80 did not provide additional information to mean doses. D80 of bilateral glands is a new factor and more predictive than mean dose regarding grade ≥3 xerostomia.

The First Prognostic Tool to Estimate the Risk of Late Grade ≥3 Xerostomia in Patients Irradiated for Head-and-Neck Cancer

BACKGROUND/AIM

Xerostomia is a serious complication following radiotherapy of head-and-neck cancers. A prognostic tool was developed for estimating its risk.

PATIENTS AND METHODS

In our previous study, age, tumor site, bilateral lymph node involvement, definitive radiotherapy, and addition of systemic therapies showed significant associations with grade ≥3 late xerostomia or trends. In additional analyses, mean radiation dose to ipsilateral parotid gland was significant (p=0.011). These six factors were included in the prognostic tool. Scoring points of 0 (lower risk) or 1 (higher risk) were assigned to each factor and added for each patient.

RESULTS

Patient scores ranged between 0 and 6; Grade ≥3 xerostomia rates were 0%, 8%, 24%, 26%, 25%, 42%, and 100%, respectively. Three groups were designed (0-1, 2-4, and 5-6 points) with grade ≥3 xerostomia rates of 5%, 25%, and 50%, respectively (p<0.001).

CONCLUSION

This new tool helps estimating the risk of radiation-induced grade ≥3 xerostomia. It can support physicians and other medical staff members during treatment planning.

Improvement of Sleep Disorders During a Course of Radiotherapy for Breast Cancer - Final Results of the Prospective Interventional RADIO-SLEEP Trial

BACKGROUND/AIM

Upcoming radiotherapy may cause distress and sleep disorders (SDO). This prospective interventional trial investigated SDO during a course of radiotherapy for breast cancer.

PATIENTS AND METHODS

Fifty patients were eligible. The primary endpoint was improvement of SDO after 15 fractions. Additional endpoints included SDO after 5 fractions and at the end of radiotherapy (EOT). Additional characteristics were analysed including use of smartphones/tablets, age, body mass index, performance score, comorbidity score, surgery, distress score, and emotional/ physical/practical problems.

RESULTS

After 15 fractions, 38% of patients reported improvement of SDO (p<0.0001). Improvement rates were 22% after 5 fractions (p=0.003) and 39% at EOT (p<0.0001). Moreover, a significant association was observed for lower distress score after 5 fractions.

CONCLUSION

Improvement of SDO occurred more often than expected, most likely due to habituation to radiotherapy. Since SDO did not improve in the majority of patients, timely psychological support should be offered to all patients.

Prognostic Value of Preclinical Markers after Radiotherapy of Metastatic Spinal Cord Compression-An Additional Analysis of Patients from Two Prospective Trials

For optimal personalization of treatment for metastatic spinal cord compression (MSCC), the patient’s survival prognosis should be considered. Estimation of survival can be facilitated by prognostic factors. This study investigated the prognostic value of pre-treatment preclinical markers, namely hemoglobin, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lactate dehydrogenase (LDH), and c-reactive protein (CRP), in 190 patients from two prospective trials who had poor or intermediate survival prognoses and were irradiated for MSCC with motor deficits. In addition, clinical factors including radiation regimen, age, gender, tumor type, interval from tumor diagnosis to MSCC, number of affected vertebrae, visceral metastases, other bone metastases, time developing motor deficits, ambulatory status, sensory function, and sphincter function were evaluated. On univariate analyses, NLR (p = 0.033), LDH (p < 0.001), CRP (p < 0.001), tumor type (p < 0.001), pre-radiotherapy ambulatory status (p < 0.001), and sphincter function (p = 0.011) were significant. In the subsequent Cox regression analysis, LDH (p = 0.007), CRP (p = 0.047), tumor type (p = 0.003), and ambulatory status (p = 0.010) maintained significance. In addition to clinical factors, preclinical markers may help in estimating the survival of patients irradiated for MSCC. Additional prospective trials are warranted.

Non-Small Cell Lung Cancer, Version 3.2022, NCCN Clinical Practice Guidelines in Oncology

NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Non-Small Cell Lung Cancer (NSCLC) provide recommended management for patients with NSCLC, including diagnosis, primary treatment, surveillance for relapse, and subsequent treatment. Patients with metastatic lung cancer who are eligible for targeted therapies or immunotherapies are now surviving longer. This selection from the NCCN Guidelines for NSCLC focuses on targeted therapies for patients with metastatic NSCLC and actionable mutations.

Risk Factors for Xerostomia Following Radiotherapy of Head-and-Neck Cancers

BACKGROUND/AIM

Many head-and-neck cancer patients receive radiotherapy, which may be associated with significant toxicities. Xerostomia is considered one of the most debilitating late adverse events. This study was performed to identify risk factors for xerostomia.

PATIENTS AND METHODS

Several characteristics were investigated for associations with late xerostomia in 159 patients irradiated for head-and-neck cancer including age, sex, tumor site and size, underlying pathology, histologic grading, upfront resection, systemic treatment, and type and dose of radiotherapy.

RESULTS

Ninety (57%) and 35 (22%) patients experienced grade ≥2 and ≥3 xerostomia, respectively. Grade ≥2 xerostomia was significantly associated with tumor site (nasopharynx/oropharynx/oral cavity/floor of mouth, p=0.049). Grade ≥3 xerostomia was significantly associated with age ≥61 years (p=0.035); trends were found for tumor site (p=0.088), bilateral nodal involvement (p=0.093), definitive treatment (p=0.082), and systemic treatment (p=0.055).

CONCLUSION

Risk factors for xerostomia following radiotherapy of head-and-neck cancers were identified including older age, unfavorable tumor site, bilateral involvement of lymph nodes, definitive treatment, and addition of systemic therapies. For patients with risk factors, sparing of the salivary glands is particularly important.

Prognostic Factors of Survival After Radiotherapy for Lung Cancer-The Impact of Smoking Pack Years

BACKGROUND/AIM

The prognostic role of smoking pack years after thoracic irradiation for lung cancer needs further clarification, since previous studies showed conflicting results. Therefore, this study investigated potential prognostic factors for survival including pack years in 170 lung cancer patients receiving local radiotherapy.

PATIENTS AND METHODS

Twelve factors were retrospectively evaluated for survival including age, sex, tumor site, histology, primary tumor stage, nodal stage, distant metastasis, radiation dose, upfront surgery or systemic treatment, pulmonary function, and number of pack years.

RESULTS

On univariate analyses, absence of distant metastasis (p=0.049), radiation dose >56 Gy (p=0.019), and ≤40 pack years (p=0.005) were significantly associated with better survival. In the multivariate analysis, number of pack years (hazard ratio 2.18, 95% confidence interval 1.25-3.82, p=0.006) maintained significance; distant metastasis (p=0.34) and radiation dose (p=0.16) were not significant.

CONCLUSION

Number of pack years was an independent predictor of survival after thoracic irradiation for lung cancer.

GPU-accelerated Monte Carlo-based online adaptive proton therapy - a feasibility study

PURPOSE

To develop an online Graphic-Processing-Unit (GPU)-accelerated Monte-Carlo-based adaptive radiation therapy (ART) workflow for pencil beam scanning (PBS) proton therapy to address inter-fraction anatomical changes in patients treated with PBS.

METHODS AND MATERIALS

A four-step workflow was developed using our in-house developed GPU-accelerated Monte-Carlo-based treatment planning system to implement online Monte-Carlo-based ART for PBS. The first step conducts diffeomorphic demon-based deformable image registration (DIR) to propagate contours on the initial planning CT (pCT) to the verification CT (vCT) to form a new structure set. The second step performs forward dose calculation of the initial plan on the vCT with the propagated contours after manual approval (possible modifications involved). The third step triggers a re-optimization of the plan depending on whether the verification dose meets the clinical requirements or not. A robust evaluation will be done for both the verification plan in the second step and the re-opotimized plan in the third step. The fourth step involves a two-stage (before and after delivery) patient specific quality assurance (PSQA) of the re-optimized plan. The before-delivery PSQA is to compare the plan dose to the dose calculated using an independent fast open-source Monte Carlo code, MCsquare. The after-delivery PSQA is to compare the plan dose to the dose re-calculated using the log file (spot MU, spot position, and spot energy) collected during the delivery. Jaccard index (JI), Dice similarity coefficients (DSCs), and Hausdorff distance (HD) were used to assess the quality of the propagated contours in the first step. A commercial plan evaluation software, ClearCheck™, was integrated into the workflow to carry out efficient plan evaluation. 3D Gamma analysis was used during the fourth step to ensure the accuracy of the plan dose from re-optimization. Three patients with three different disease sites were chosen to evaluate the feasibility of the online ART workflow for PBS.

RESULTS

For all three patients, the propagated contours were found to have good volume conformance [JI (lowest-highest: 0.833-0.983) and DSC (0.909-0.992)] but sub-optimal boundary coincidence [HD (2.37-20.76 mm)] for organs at risk (OARs). The verification dose evaluated by ClearCheck™ showed significant degradation of the target coverage due to the inter-fractional anatomical changes. Re-optimization on the vCT resulted in great improvement of the plan quality to a clinically acceptable level. 3D Gamma analyses of PSQA confirmed the accuracy of the plan dose before delivery (mean Gamma index = 98.74% with a threshold of 2%/2 mm/10%), and after delivery based on the log files (mean Gamma index = 99.05% with a threshold of 2%/2 mm/10%). The average time cost for the complete execution of the workflow was around 858 seconds, excluding the time for manual intervention.

CONCLUSION

The proposed online ART workflow for PBS was demonstrated to be efficient and effective by generating a re-optimized plan that significantly improved the plan quality. This article is protected by copyright. All rights reserved.

Pediatric Pineoblastoma: A pooled outcome study of North American and Australian therapeutic data

Background

Pineoblastoma is a rare brain tumor usually diagnosed in children. Given its rarity, no pineoblastoma specific trials have been conducted. Studies have included pineoblastoma accruing for other embryonal tumors over the past 30 years. These included only occasional children with pineoblastoma, making clinical features difficult to interpret and determinants of outcome difficult to ascertain.

Patients and Methods

Centrally or independently reviewed series with treatment and survival data from North American and Australian cases were pooled. To investigate associations between variables, Fisher’s exact tests, Wilcoxon-Mann-Whitney tests, and Spearman correlations were used. Kaplan-Meier plots, log-rank tests, and Cox proportional hazards models were used in survival analyses.

Results

We describe a pooled cohort of 178 pineoblastoma cases from Children’s Oncology Group (n=82) and institutional series (n=96) over 30 years. Children &lt;3 years of age have significantly worse survival compared to older children, with 5-year progression free survival and overall survival estimates of 13.5±5.1% and 16.2±5.3% respectively compared with 60.8±5.6% and 67.3±5.0% for ≥3 years old (both p&lt;0.0001). Multivariable analysis showed male sex was associated with worse PFS in children &lt;3 years of age (Hazard Ratio 3.93, 95% CI 1.80-8.55; p=0.0006), suggestive of sex specific risks needing future validation. For children ≥3 years of age, disseminated disease at diagnosis was significantly associated with an inferior 5-year PFS of 39.2±9.7% (HR 2.88, 95% CI 1.52-5.45; p=0.0012) and 5-year OS of 49.8±9.1% (HR 2.87, 95% CI 1.49-5.53; p=0.0016).

Conclusion

Given the rarity of this tumor, prospective, collaborative international studies will be vital to improving the long-term survival of these patients.

Estimating the Probability of Not Completing the Intended Course of Thoracic Radiotherapy for Lung Cancer

BACKGROUND/AIM

In some patients with lung cancer scheduled for thoracic radiotherapy (RT), treatment is discontinued before reaching the planned dose. For optimal treatment personalization, a tool estimating whether a patient can complete radiotherapy would be helpful.

PATIENTS AND METHODS

Eleven pre-RT characteristics were analyzed in 170 patients receiving local RT for lung cancer. Characteristics included age, sex, tumor site, histology, tumor and nodal stage, distant metastasis, surgery, systemic treatment, pulmonary function, and smoking history.

RESULTS

Age >75 years (p=0.038), distant metastasis (p=0.009), and forced expiratory volume in 1 second <1.2 l (p=0.038) were significantly associated with discontinuation of RT. A prognostic instrument was developed in 126 patients with complete data regarding these characteristics. It included three groups (0, 1, and 2-3 points) with non-completion rates of 33.3%, 55.0% and 75.0% (p=0.004).

CONCLUSION

This new instrument can help estimating the probability that lung cancer patients assigned to local RT cannot complete the planned course of RT.

Empirical Relative Biological Effectiveness (RBE) for Mandible Osteoradionecrosis (ORN) in Head and Neck Cancer Patients Treated With Pencil-Beam-Scanning Proton Therapy (PBSPT): A Retrospective, Case-Matched Cohort Study

Purpose

To retrospectively investigate empirical relative biological effectiveness (RBE) for mandible osteoradionecrosis (ORN) in head and neck (H&N) cancer patients treated with pencil-beam-scanning proton therapy (PBSPT).

Methods

We included 1,266 H&N cancer patients, of which, 931 patients were treated with volumetric-modulated arc therapy (VMAT) and 335 were treated with PBSPT. Among them, 26 VMAT and 9 PBSPT patients experienced mandible ORN (ORN group), while all others were included in the control group. To minimize the impact of the possible imbalance in clinical factors between VMAT and PBSPT patients in the dosimetric comparison between these two modalities and the resulting RBE quantification, we formed a 1:1 case-matched patient cohort (335 VMAT patients and 335 PBSPT patients including both the ORN and control groups) using the greedy nearest neighbor matching of propensity scores. Mandible dosimetric metrics were extracted from the case-matched patient cohort and statistically tested to evaluate the association with mandibular ORN to derive dose volume constraints (DVCs) for VMAT and PBSPT, respectively. We sought the equivalent constraint doses for VMAT so that the critical volumes of VMAT were equal to those of PBSPT at different physical doses. Empirical RBEs of PBSPT for ORN were obtained by calculating the ratio between the derived equivalent constraint doses and physical doses of PBSPT. Bootstrapping was further used to get the confidence intervals.

Results

Clinical variables of age, gender, tumor stage, prescription dose, chemotherapy, hypertension or diabetes, dental extraction, smoking history, or current smoker were not statistically related to the incidence of ORN in the overall patient cohort. Smoking history was found to be significantly associated with the ORN incidence in PBSPT patients only. V40Gy[RBE], V50Gy[RBE], and V60Gy[RBE] were statistically different (p<0.05) between the ORN and control group for VMAT and PBSPT. Empirical RBEs of 1.58(95%CI: 1.34-1.64), 1.34(95%CI: 1.23-1.40), and 1.24(95%: 1.15-1.26) were obtained for proton dose at 40 Gy[RBE=1.1], 50 Gy[RBE=1.1] and 60 Gy[RBE=1.1], respectively.

Conclusions

Our study suggested that RBEs were larger than 1.1 at moderate doses (between 40 and 60 Gy[RBE=1.1]) with high LET for mandible ORN. RBEs are underestimated in current clinical practice in PBSPT. The derived DVCs can be used for PBSPT plan evaluation and optimization to minimize the incidence rate of mandible ORN.

Gastroesophageal reflux disease and paraneoplastic neurological syndrome associated with long-term survival in limited stage small-cell lung cancer

Introduction

Patients with small‐cell lung cancer (SCLC) have a very poor prognosis. However, a subset of SCLC achieves long‐term survival. The objective of this study was to investigate factors and pattern of long‐term survival in patients with limited‐stage small cell lung cancer (LS‐SCLC) who achieved a complete response (CR) after chemoradiotherapy.

Patient and Methods

This was a single‐center retrospective study. The analysis of hazard ratio (HR) and 95% confidence interval (CI) was performed using Cox proportional hazards model. For pattern analysis, the date of recurrence was used as the endpoint. The nominal categorical variables were analyzed by the χ² test. Survival was estimated using the Kaplan–Meier model, and the results were reported as the median and interquartile range.

Results

We identified 162 patients, median age was 64.7 (56.2–70.2) years, and 94 (58%) were females. Eighty‐one patients (50%) had recurrence during follow‐up. Gastroesophageal reflux disease (GERD) (HR, 0.65; 95% CI, 0.45–0.93; p = 0.016) and neurological paraneoplastic syndrome (PNS) (HR, 0.46; 95% CI, 0.29–0.72; p < 0.001) were independent factors associated with improved overall survival (OS). Patients with GERD had prolonged recurrence free survival (RFS) compared to patients without GERD (median, 29.1 months vs. 13.9 months, p < 0.001), whereas patients with neurological PNS had a reduced recurrence rate compared to those patients without neurological PNS (No. [%], 8 [20.5] vs. 73 [59.3], p < 0.001).

Conclusions

Patients with LS‐SCLC achieving a CR after chemoradiotherapy, GERD, and neurological PNS were associated with improved OS. GERD and neurological PNS were associated with longer RFS and lower recurrence rate, respectively.

Risk Factors for Sleep Problems Prior to Radiochemotherapy for Malignant Gliomas

BACKGROUND/AIM

Many patients with malignant gliomas are scheduled for radiochemotherapy, which may cause emotional distress associated with sleep problems. This study aimed to determine the prevalence of such sleep problems in these patients and identify risk factors.

PATIENTS AND METHODS

Fifty-seven patients scheduled for radiochemotherapy for grade II-IV gliomas were retrospectively investigated for pre-treatment sleep problems. Fifteen characteristics were evaluated including temporal relation to COVID-19 pandemic, age, gender, performance status, comorbidity, (family) history of malignancies, distress score, emotional problems, physical problems, practical problems, involved sites, glioma grade, upfront surgery, and corticosteroids.

RESULTS

Nineteen patients stated pre-treatment sleep problems (prevalence=66.7%). Significant associations with sleep problems were found for female gender (p=0.023), presence of emotional problems (p=0.006), and ≥4 physical problems (p<0.001). A trend was found for distress scores ≥5 (p=0.077).

CONCLUSION

The prevalence of sleep problems was high. Risk factors were determined that can be used to identify patients who likely benefit from psychological support.

Role of Prophylactic Cranial Irradiation in Extensive-Stage Small Cell Lung Cancer

Patients with small cell lung cancer (SCLC) are at significant risk of developing brain metastases during their disease course. Prophylactic cranial irradiation (PCI) has been incorporated into SCLC treatment guidelines to diminish the risk of developing brain metastases. In 2007, a randomized trial suggested that PCI decreases the incidence of brain metastases and prolongs overall survival (OS) in patients with extensive-stage SCLC (ES-SCLC) who have responded to initial therapy. However, this study did not include modern central nervous system imaging with CT or MRI prior to randomization. A more recent Japanese trial with MRI staging and surveillance demonstrated that PCI diminished the incidence of brain metastases but did not improve survival. This review examines the largest clinical studies, controversies, and future directions of PCI in patients with ES-SCLC.