Deep learning-based ultrasound auto-segmentation of the prostate with brachytherapy implanted needles

BACKGROUND

Accurate segmentation of the clinical target volume (CTV) corresponding to the prostate with or without proximal seminal vesicles is required on transrectal ultrasound (TRUS) images during prostate brachytherapy procedures. Implanted needles cause artifacts that may make this task difficult and time-consuming. Thus, previous studies have focused on the simpler problem of segmentation in the absence of needles at the cost of reduced clinical utility.

PURPOSE

To use a convolutional neural network (CNN) algorithm for segmentation of the prostatic CTV in TRUS images post-needle insertion obtained from prostate brachytherapy procedures to better meet the demands of the clinical procedure.

METHODS

A dataset consisting of 144 3-dimensional (3D) TRUS images with implanted metal brachytherapy needles and associated manual CTV segmentations was used for training a 2-dimensional (2D) U-Net CNN using a Dice Similarity Coefficient (DSC) loss function. These were split by patient, with 119 used for training and 25 reserved for testing. The 3D TRUS training images were resliced at radial (around the axis normal to the coronal plane) and oblique angles through the center of the 3D image, as well as axial, coronal, and sagittal planes to obtain 3689 2D TRUS images and masks for training. The network generated boundary predictions on 300 2D TRUS images obtained from reslicing each of the 25 3D TRUS images used for testing into 12 radial slices (15° apart), which were then reconstructed into 3D surfaces. Performance metrics included DSC, recall, precision, unsigned and signed volume percentage differences (VPD/sVPD), mean surface distance (MSD), and Hausdorff distance (HD). In addition, we studied whether providing algorithm-predicted boundaries to the physicians and allowing modifications increased the agreement between physicians. This was performed by providing a subset of 3D TRUS images of five patients to five physicians who segmented the CTV using clinical software and repeated this at least 1 week apart. The five physicians were given the algorithm boundary predictions and allowed to modify them, and the resulting inter- and intra-physician variability was evaluated.

RESULTS

Median DSC, recall, precision, VPD, sVPD, MSD, and HD of the 3D-reconstructed algorithm segmentations were 87.2 [84.1, 88.8]%, 89.0 [86.3, 92.4]%, 86.6 [78.5, 90.8]%, 10.3 [4.5, 18.4]%, 2.0 [-4.5, 18.4]%, 1.6 [1.2, 2.0] mm, and 6.0 [5.3, 8.0] mm, respectively. Segmentation time for a set of 12 2D radial images was 2.46 [2.44, 2.48] s. With and without U-Net starting points, the intra-physician median DSCs were 97.0 [96.3, 97.8]%, and 94.4 [92.5, 95.4]% (p < 0.0001), respectively, while the inter-physician median DSCs were 94.8 [93.3, 96.8]% and 90.2 [88.7, 92.1]%, respectively (p < 0.0001). The median segmentation time for physicians, with and without U-Net-generated CTV boundaries, were 257.5 [211.8, 300.0] s and 288.0 [232.0, 333.5] s, respectively (p = 0.1034).

CONCLUSIONS

Our algorithm performed at a level similar to physicians in a fraction of the time. The use of algorithm-generated boundaries as a starting point and allowing modifications reduced physician variability, although it did not significantly reduce the time compared to manual segmentations.

Optimizing Clinical Implementation of Hypofractionation: Comprehensive Evidence Synthesis and Practical Guidelines for Low- and Middle-Income Settings

The global cancer burden, especially in low- and middle-income countries (LMICs), worsens existing disparities, amplified by the rising costs of advanced treatments. The shortage of radiation therapy (RT) services is a significant issue in LMICs. Extended conventional treatment regimens pose significant challenges, especially in resource-limited settings. Hypofractionated radiotherapy (HRT) and ultra-hypofractionated/stereotactic body radiation therapy (SBRT) offer promising alternatives by shortening treatment durations. This approach optimizes the utilization of radiotherapy machines, making them more effective in meeting the growing demand for cancer care. Adopting HRT/SBRT holds significant potential, especially in LMICs. This review provides the latest clinical evidence and guideline recommendations for the application of HRT/SBRT in the treatment of breast, prostate, and lung cancers. It emphasizes the critical importance of rigorous training, technology, stringent quality assurance, and safety protocols to ensure precise and secure treatments. Additionally, it addresses practical considerations for implementing these treatments in LMICs, highlighting the need for comprehensive support and collaboration to enhance patient access to advanced cancer care.

Hypofractionated Radiotherapy in Gynecologic Malignancies-A Peek into the Upcoming Evidence

Radiotherapy (RT) has a fundamental role in the treatment of gynecologic malignancies, including cervical and uterine cancers. Hypofractionated RT has gained popularity in many cancer sites, boosted by technological advances in treatment delivery and image verification. Hypofractionated RT uptake was intensified during the COVID-19 pandemic and has the potential to improve universal access to radiotherapy worldwide, especially in low-resource settings. This review summarizes the rationale, the current challenges and investigation efforts, together with the recent developments associated with hypofractionated RT in gynecologic malignancies. A comprehensive search was undertaken using multiple databases and ongoing trial registries. In the definitive radiotherapy setting for cervical cancers, there are several ongoing clinical trials from Canada, Mexico, Iran, the Philippines and Thailand investigating the role of a moderate hypofractionated external beam RT regimen in the low-risk locally advanced population. Likewise, there are ongoing ultra and moderate hypofractionated RT trials in the uterine cancer setting. One Canadian prospective trial of stereotactic hypofractionated adjuvant RT for uterine cancer patients suggested a good tolerance to this treatment strategy in the acute setting, with a follow-up trial currently randomizing patients between conventional fractionation and the hypofractionated dose regimen delivered in the former trial. Although not yet ready for prime-time use, hypofractionated RT could be a potential solution to several challenges that limit access to and the utilization of radiotherapy for gynecologic cancer patients worldwide.

Is Ultrahypofractionated Whole Pelvis Radiation Therapy (WPRT) as Well Tolerated as Conventionally Fractionated WPRT in Patients With Prostate Cancer? Early Results From the HOPE Trial

OBJECTIVE

The aim of this work was to evaluate the acute toxicity and quality-of-life (QOL) impact of ultrahypofractionated whole pelvis radiation therapy (WPRT) compared with conventional WPRT fractionation after high-dose-rate prostate brachytherapy (HDR-BT).

METHODS AND MATERIALS

The HOPE trial is a phase 2, multi-institutional randomized controlled trial of men with prostate-confined disease and National Comprehensive Cancer Network unfavorable intermediate-, high-, or very-high-risk prostate cancer. Patients were randomly assigned to receive conventionally fractionated WPRT (standard arm) or ultrahypofractionated WPRT (experimental arm) in a 1:1 ratio. All patients underwent radiation therapy with 15 Gy HDR-BT boost in a single fraction followed by WPRT delivered with conventional fractionation (45 Gy in 25 daily fractions or 46 Gy in 23 fractions) or ultrahypofractionation (25 Gy in 5 fractions delivered on alternate days). Acute toxicities measured during radiation therapy and at 6 weeks posttreatment were assessed using the clinician-reported Common Terminology Criteria for Adverse Events version 5.0, and QOL was measured using the Expanded Prostate Cancer Index Composite (EPIC-50) and International Prostate Symptom Score (IPSS).

RESULTS

A total of 80 patients were enrolled and treated across 3 Canadian institutions, of whom 39 and 41 patients received external radiation therapy with conventionally fractionated and ultrahypofractionated WPRT, respectively. All patients received androgen deprivation therapy except for 2 patients treated in the ultrahypofractionated arm. The baseline clinical characteristics of the 2 arms were similar, with 51 (63.8%) patients having high or very-high-risk prostate cancer disease. Treatment was well tolerated with no significant differences in the rate of acute adverse events between arms. No grade 4 adverse events or treatment-related deaths were reported. Ultrahypofractionated WPRT had a less detrimental impact on the EPIC-50 bowel total, function, and bother domain scores compared with conventional WPRT in the acute setting. By contrast, more patients treated with ultrahypofractionated WPRT reached the minimum clinical important difference on the EPIC-50 urinary domains. No significant QOL differences between arms were noted in the sexual and hormonal domains.

CONCLUSIONS

Ultrahypofractionated WPRT after HDR-BT is a well-tolerated treatment strategy in the acute setting that has less detrimental impact on bowel QOL domains compared with conventional WPRT.

18F-DCFPyL PSMA-PET affects management of salvage radiotherapy for post-prostatectomy patients with biochemical failure: A matched cohort study

INTRODUCTION

Our objective was to assess the effect of 18F-DCFPyL prostate-specific membrane antigen (PSMA) positron emission tomography (PET) on the management and outcomes of patients receiving salvage radiotherapy following biochemical failure (BF) post-radical prostatectomy (RP) using a matched cohort analysis.

METHODS

A PSMA-PET cohort of patients with BF post-RP was identified through a prospective registry. Patients from this registry were included if they did not have disease outside of the pelvis and underwent salvage radiotherapy to the prostate and/or pelvis. Case-control matching was performed with a contemporary cohort of patients with BF post-RP without PSMA-PET information.

RESULTS

Forty-four patients were included in the PSMA-PET cohort and 80 were analyzed in the non-PSMA-PET cohort. The PSMA-PET cohort had a significantly higher pre-radiotherapy median prostate-specific antigen (PSA) of 0.48 ng/mL compared to 0.20 ng/mL in the non-PSMA-PET cohort (p<0.001), but these levels were similar after matching. The PSMA-PET cohort had a higher proportion of patients receiving radiotherapy to pelvic lymph nodes (n=27 [61.4%] vs. n=16 [20.0%], p<0.001). Median followup was 26 months (interquartile range 18.8-33) for both cohorts. BF-free survival and event-free survival were not significantly different between the two cohorts for all (p=0.662 and >0.99) and matched patients (p=0.808 and 0.808), respectively. Metastasis-free survival was significantly higher in the matched PSMA-PET cohort compared to the matched non-PSMA-PET cohort (p=0.046), although a higher proportion of patients in the non-PSMA-PET cohort underwent PSMA-PET restaging after BF (52% vs. 20%, p=0.08726).

CONCLUSIONS

Our study showed that patients undergoing PSMA-PET scans after BF post-RP had a higher likelihood of pelvic nodal treatment at the time of salvage RT. Despite higher PSA levels at salvage, we identified no recurrence or survival differences.

Analysis of a Biopsy-Based Genomic Classifier in High-Risk Prostate Cancer: Meta-Analysis of the NRG Oncology/Radiation Therapy Oncology Group 9202, 9413, and 9902 Phase 3 Randomized Trials

PURPOSE

Decipher is a genomic classifier (GC) prospectively validated postprostatectomy. We validated the performance of the GC in pretreatment biopsy samples within the context of 3 randomized phase 3 high-risk definitive radiation therapy trials.

METHODS AND MATERIALS

A prespecified analysis plan (NRG-GU-TS006) was approved to obtain formalin-fixed paraffin-embedded tissue from biopsy specimens from the NRG biobank from patients enrolled in the NRG/Radiation Therapy Oncology Group (RTOG) 9202, 9413, and 9902 phase 3 randomized trials. After central review, the highest-grade tumors were profiled on clinical-grade whole-transcriptome arrays and GC scores were obtained. The primary objective was to validate the independent prognostic ability for the GC for distant metastases (DM), and secondary for prostate cancer-specific mortality (PCSM) and overall survival (OS) with Cox univariable and multivariable analyses.

RESULTS

GC scores were obtained on 385 samples, of which 265 passed microarray quality control (69%) and had a median follow-up of 11 years (interquartile range, 9-13). In the pooled cohort, on univariable analysis, the GC was shown to be a prognostic factor for DM (per 0.1 unit; subdistribution hazard ratio [sHR], 1.29; 95% confidence interval [CI], 1.18-1.41; P < .001), PCSM (sHR, 1.28; 95% CI, 1.16-1.41; P < .001), and OS (hazard ratio [HR], 1.16; 95% CI, 1.08-1.22; P < .001). On multivariable analyses, the GC (per 0.1 unit) was independently associated with DM (sHR, 1.22; 95% CI, 1.09-1.36), PCSM (sHR, 1.23; 95% CI, 1.09-1.39), and OS (HR, 1.12; 95% CI, 1.05-1.20) after adjusting for age, Prostate Specific Antigen, Gleason score, cT stage, trial, and randomized treatment arm. GC had similar prognostic ability in patients receiving short-term or long-term androgen-deprivation therapy, but the absolute improvement in outcome varied by GC risk.

CONCLUSIONS

This is the first validation of a gene expression biomarker on pretreatment prostate cancer biopsy samples from prospective randomized trials and demonstrates an independent association of GC score with DM, PCSM, and OS. High-risk prostate cancer is a heterogeneous disease state, and GC can improve risk stratification to help personalize shared decision making.

The use of Lutetium-177 PSMA radioligand therapy with high dose rate brachytherapy for locally recurrent prostate cancer after previous definitive radiation therapy: a randomized, single-institution, phase I/II study (ROADSTER)

BACKGROUND

Isolated local failure (ILF) can occur in patients who initially receive definitive radiation therapy for prostate cancer. Salvage therapy for ILF includes high dose rate (HDR) brachytherapy. Prostate Specific Membrane Antigen (PSMA) Positron Emission Tomography (PET) can accurately detect ILF and can exclude extraprostatic disease. Lutetium-177 PSMA Radioligand Therapy (RLT) is a novel treatment for prostate cancer that can target prostate cancer accurately, while sparing radiation dose to normal tissues.

METHODS

ROADSTER is a phase I/II randomized, single-institution study. Patients with an ILF of prostate cancer after definitive initial radiation therapy are eligible. The ILF will be confirmed with biopsy, magnetic resonance imaging (MRI) and PSMA PET. Patients will be randomized between HDR brachytherapy in two fractions (a standard of care salvage treatment at our institution) (cohort 1) or one treatment of intravenous Lutetium-177 PSMA RLT, followed by one fraction of HDR brachytherapy (cohort 2). The primary endpoints for the phase I portion of the study (n = 12) will be feasibility, defined as 10 or more patients completing the study protocol within 24 months of study activation; and safety, defined as zero or one patients in cohort 2 experiencing grade 3 or higher toxicity in the first 6 months post-treatment. If feasibility and safety are achieved, the study will expand to a phase II study (n = 30 total) where preliminary efficacy data will be evaluated. Secondary endpoints include changes in prostate specific antigen levels, acute toxicity, changes in quality of life, and changes in translational biomarkers. Translational endpoints will include interrogation of blood, urine, and tissue for markers of DNA damage and immune activation with each treatment.

DISCUSSION

ROADSTER explores a novel salvage therapy for ILF after primary radiotherapy with combined Lutetium-177 PSMA RLT and HDR brachytherapy. The randomized phase I/II design will provide a contemporaneous patient population treated with HDR alone to facilitate assessment of feasibility, tolerability, and biologic effects of this novel therapy.

TRIAL REGISTRATION

NCT05230251 (ClinicalTrials.gov).

Body composition and mortality in men receiving prostate radiotherapy: A pooled analysis of NRG/RTOG 9406 and NRG/RTOG 0126

PURPOSE

To validate the association between body composition and mortality in men treated with radiation for localized prostate cancer (PCa). Secondarily, to integrate body composition as a factor to classify patients by risk of all-cause mortality.

MATERIALS AND METHODS

Participants of NRG/Radiation Therapy Oncology Group (RTOG) 9406 and NRG/RTOG 0126 with archived computed tomography were included. Muscle mass and muscle density were estimated by measuring the area and attenuation of the psoas muscles on a single slice at L4-L5. Bone density was estimated by measuring the attenuation of the vertebral body at mid-L5. Survival analyses, including Cox proportional hazards models, assessed the relationship between body composition and mortality. Recursive partitioning analysis (RPA) was used to create a classification tree to classify participants by risk of death.

RESULTS

Data from 2066 men were included in this study. In the final multivariable model, psoas area, comorbidity score, baseline prostate serum antigen, and age were significantly associated with survival. The RPA yielded a classification tree with four prognostic groups determined by age, comorbidity, and psoas area. Notably, the classification among older (≥70 years) men into prognostic groups was determined by psoas area.

CONCLUSIONS

This study strongly supports that body composition is related to mortality in men with localized PCa. The inclusion of psoas area in the RPA classification tree suggests that body composition provides additive information to age and comorbidity status for mortality prediction, particularly among older men. More research is needed to determine the clinical impact of body composition on prognostic models in men with PCa.

Validation of a surface-based deformable MRI-3D ultrasound image registration algorithm toward clinical implementation for interstitial prostate brachytherapy

PURPOSE

The purpose of this study was to evaluate and clinically implement a deformable surface-based magnetic resonance imaging (MRI) to three-dimensional ultrasound (US) image registration algorithm for prostate brachytherapy (BT) with the aim to reduce operator dependence and facilitate dose escalation to an MRI-defined target.

METHODS AND MATERIALS

Our surface-based deformable image registration (DIR) algorithm first translates and scales to align the US- and MR-defined prostate surfaces, followed by deformation of the MR-defined prostate surface to match the US-defined prostate surface. The algorithm performance was assessed in a phantom using three deformation levels, followed by validation in three retrospective high-dose-rate BT clinical cases. For comparison, manual rigid registration and cognitive fusion by physician were also employed. Registration accuracy was assessed using the Dice similarity coefficient (DSC) and target registration error (TRE) for embedded spherical landmarks. The algorithm was then implemented intraoperatively in a prospective clinical case.

RESULTS

In the phantom, our DIR algorithm demonstrated a mean DSC and TRE of 0.74 ± 0.08 and 0.94 ± 0.49 mm, respectively, significantly improving the performance compared to manual rigid registration with 0.64 ± 0.16 and 1.88 ± 1.24 mm, respectively. Clinical results demonstrated reduced variability compared to the current standard of cognitive fusion by physicians.

CONCLUSIONS

We successfully validated a DIR algorithm allowing for translation of MR-defined target and organ-at-risk contours into the intraoperative environment. Prospective clinical implementation demonstrated the intraoperative feasibility of our algorithm, facilitating targeted biopsies and dose escalation to the MR-defined lesion. This method provides the potential to standardize the registration procedure between physicians, reducing operator dependence.

A power Doppler ultrasound method for improving intraoperative tip localization for visually obstructed needles in interstitial prostate brachytherapy

PURPOSE

High-dose-rate (HDR) interstitial brachytherapy (BT) is a common treatment technique for localized intermediate to high-risk prostate cancer. Transrectal ultrasound (US) imaging is typically used for guiding needle insertion, including localization of the needle tip which is critical for treatment planning. However, image artifacts can limit needle tip visibility in standard brightness (B)-mode US, potentially leading to dose delivery that deviates from the planned dose. To improve intraoperative tip visualization in visually obstructed needles, we propose a power Doppler (PD) US method which utilizes a novel wireless mechanical oscillator, validated in phantom experiments and clinical HDR-BT cases as part of a feasibility clinical trial.

METHODS

Our wireless oscillator contains a DC motor housed in a 3D printed case and is powered by rechargeable battery allowing the device to be operated by one person with no additional equipment required in the operating room. The oscillator end-piece features a cylindrical shape designed for BT applications to fit on top of the commonly used cylindrical needle mandrins. Phantom validation was completed using tissue-equivalent agar phantoms with the clinical US system and both plastic and metal needles. Our PD method was tested using a needle implant pattern matching a standard HDR-BT procedure as well as an implant pattern designed to maximize needle shadowing artifacts. Needle tip localization accuracy was assessed using the clinical method based on ideal reference needles as well as a comparison to computed tomography (CT) as a gold standard. Clinical validation was completed in five patients who underwent standard HDR-BT as part of a feasibility clinical trial. Needle tips positions were identified using B-mode US and PD US with perturbation from our wireless oscillator.

RESULTS

Absolute mean ± standard deviation tip error for B-mode alone, PD alone, and B-mode combined with PD was respectively: 0.3 ± 0.3 mm, 0.6 ± 0.5 mm, and 0.4 ± 0.2 mm for the mock HDR-BT needle implant; 0.8 ± 1.7 mm, 0.4 ± 0.6 mm, and 0.3 ± 0.5 mm for the explicit shadowing implant with plastic needles; and 0.5 ± 0.2 mm, 0.5 ± 0.3 mm, and 0.6 ± 0.2 mm for the explicit shadowing implant with metal needles. The total mean absolute tip error for all five patients in the feasibility clinical trial was 0.9 ± 0.7 mm using B-mode US alone and 0.8 ± 0.5 mm when including PD US, with increased benefit observed for needles classified as visually obstructed.

CONCLUSIONS

Our proposed PD needle tip localization method is easy to implement and requires no modifications or additions to the standard clinical equipment or workflow. We have demonstrated decreased tip localization error and variation for visually obstructed needles in both phantom and clinical cases, including providing the ability to visualize needles previously not visible using B-mode US alone. This method has the potential to improve needle visualization in challenging cases without burdening the clinical workflow, potentially improving treatment accuracy in HDR-BT and more broadly in any minimally invasive needle-based procedure.

Opioid consumption and pain in patients with gynecological cancer who underwent spinal anesthesia vs. general anesthesia for interstitial brachytherapy

AIMS

Interstitial brachytherapy (ISBT) is an effective option for delivering conformal high dose radiation to the target volume with better organ-at risk sparing but is thought to be more invasive and painful than other methods. This study investigated pain levels and opioid consumption in patients who received spinal anesthesia (SA) or general anesthesia (GA) for their ISBT.

MATERIALS AND METHODS

Patients that underwent ISBT from April 2014 to September 2018 were analyzed from a prospective institutional database. The most prevalent malignancies were cervical (45%), recurrent endometrial (27%) and vaginal (20%) cancers. Baseline patient characteristics, radiation treatment details, anesthesia records, and inpatient charts were obtained. Opioid consumption was quantified as oral morphine equivalent per day (OMEq/day) from implantation until removal. Pain score levels were collected by using an 11-point scoring system.

RESULTS

Ninety nine patients received GA and 40 patients received SA as their anesthesia for ISBT. During their first admission, 76 patients (55%) required intravenous opioids. Patients receiving SA had significantly lower mean pain scores on the morning of their procedure 6 (Interquartile range [IQR] 2-8) vs. 0 (IQR: 0-1); p < 0.001]. Pain did not significantly differ between cohorts at any other time. During the first admission, SA patients had a lower median opioid usage of 23 (IQR: 9-47) mg/day compared to GA patients at 38 (IQR: 21-71) mg/day (p = 0.011). No difference in opioid consumption was seen during subsequent admissions.

CONCLUSIONS

In patients undergoing ISBT, SA provides better immediate pain control post insertion compared to GA. Patients who received SA used lower amounts of opioids during their first ISBT insertion.

Does brachytherapy boost improve survival outcomes in Gleason Grade Group 5 patients treated with external beam radiotherapy and androgen deprivation therapy? A systematic review and meta-analysis

•

Adding a BT boost to external beam radiation can be used to intensify treatment.

•

BT boost improves DMFS but not PCSS or OS in Gleason GG5 prostate cancer.

•

There is no prospective data evaluating BT boost in Gleason GG5 disease.

Background

Localized Gleason Grade Group 5 (GG5) prostate cancer has a poor prognosis and is associated with a higher risk of treatment failure, metastases, and death. Treatment intensification with the addition of a brachytherapy (BT) boost to external beam radiation (EBRT) maximizes local control, which may translate into improved survival outcomes.

Methods

A systematic review and meta-analysis was performed to compare survival outcomes for Gleason GG5 patients treated with androgen deprivation therapy (ADT) and either EBRT or EBRT + BT. The MEDLINE (PubMed), EMBASE and Cochrane databases were searched to identify relevant studies. Survival probabilities for distant metastasis-free survival (DMFS), prostate cancer-specific survival (PCSS), and overall survival (OS) were extracted and pooled to create a summary survival curve for each treatment modality, which were then compared at fixed points in time. An additional analysis was performed among studies directly comparing EBRT and EBRT + BT using a random-effects model.

Results

Eight retrospective studies were selected for inclusion, representing a total of 1393 EBRT patients and 877 EBRT + BT patients. EBRT + BT was associated with higher DMFS starting at 6 years (86.8 % vs 78.8 %; p = 0.018) and extending out to 10 years (81.8 % vs 66.1 %; p < 0.001), with an overall hazard ratio of 0.53 (p = 0.02). There was no difference in PCSS or OS between treatment modalities. Differences in toxicity were not assessed. There was a wide range of heterogeneity between studies.

Conclusion

The addition of BT boost is associated with improved long-term DMFS in Gleason GG5 prostate cancer, but its impact on PCSS and OS remains unclear. These results may be confounded by the heterogeneity across study populations with concern for a risk of bias. Therefore, prospective studies are necessary to further elucidate the survival advantage associated with BT boost, which must ultimately be weighed against the toxicity-related implications of this treatment strategy.

An international Delphi consensus for pelvic stereotactic ablative radiotherapy re-irradiation

INTRODUCTION

Stereotactic Ablative Radiotherapy (SABR) is increasingly used to treat metastatic oligorecurrence and locoregional recurrences but limited evidence/guidance exists in the setting of pelvic re-irradiation. An international Delphi study was performed to develop statements to guide practice regarding patient selection, pre-treatment investigations, treatment planning, delivery and cumulative organs at risk (OARs) constraints.

MATERIALS AND METHODS

Forty-one radiation oncologists were invited to participate in three online surveys. In Round 1, information and opinion was sought regarding participants' practice. Guidance statements were developed using this information and in Round 2 participants were asked to indicate their level of agreement with each statement. Consensus was defined as ≥75% agreement. In Round 3, any statements without consensus were re-presented unmodified, alongside a summary of comments from Round 2.

RESULTS

Twenty-three radiation oncologists participated in Round 1 and, of these, 21 (91%) and 22 (96%) completed Rounds 2 and 3 respectively. Twenty-nine of 44 statements (66%) achieved consensus in Round 2. The remaining 15 statements (34%) did not achieve further consensus in Round 3. Consensus was achieved for 10 of 17 statements (59%) regarding patient selection/pre-treatment investigations; 12 of 13 statements (92%) concerning treatment planning and delivery; and 7 of 14 statements (50%) relating to OARs. Lack of agreement remained regarding the minimum time interval between irradiation courses, the number/size of pelvic lesions that can be treated and the most appropriate cumulative OAR constraints.

CONCLUSIONS

This study has established consensus, where possible, in areas of patient selection, pre-treatment investigations, treatment planning and delivery for pelvic SABR re-irradiation for metastatic oligorecurrence and locoregional recurrences. Further research into this technique is required, especially regarding aspects of practice where consensus was not achieved.

Feasibility of fusing three-dimensional transabdominal and transrectal ultrasound images for comprehensive intraoperative visualization of gynecologic brachytherapy applicators

PURPOSE

In this study, we propose combining three-dimensional (3D) transrectal ultrasound (TRUS) and 3D transabdominal ultrasound (TAUS) images of gynecologic brachytherapy applicators to leverage the advantages of each imaging perspective, providing a broader field-of-view and allowing previously obscured features to be recovered. The aim of this study was to evaluate the feasibility of fusing these 3D ultrasound (US) perspectives based on the applicator geometry in a phantom prior to clinical implementation.

METHODS

In proof-of-concept experiments, 3D US images of application-specific multimodality pelvic phantoms were acquired with tandem-and-ring and tandem-and-ovoids applicators using previously validated imaging systems. Two TRUS images were acquired at different insertion depths and manually fused based on the position of the ring/ovoids to broaden the TRUS field-of-view. The phantom design allowed "abdominal thickness" to be modified to represent different body habitus and TAUS images were acquired at three thicknesses for each applicator. The merged TRUS images were then combined with TAUS images by rigidly aligning applicator components and manually refining the registration using the positions of source channels and known tandem length, as well as the ring diameter for the tandem-and-ring applicator. Combined 3D US images were manually, rigidly registered to images from a second modality (magnetic resonance (MR) imaging for the tandem-and-ring applicator and X-ray computed tomography (CT) for the tandem-and-ovoids applicator (based on applicator compatibility)) to assess alignment. Four spherical fiducials were used to calculate target registration errors (TREs), providing a metric for validating registrations, where TREs were computed using root-mean-square distances to describe the alignment of manually identified corresponding fiducials. An analysis of variance (ANOVA) was used to identify statistically significant differences (p < 0.05) between the TREs for the three abdominal thicknesses for each applicator type. As an additional indicator of geometric accuracy, the bladder was segmented in the 3D US and corresponding MR/CT images, and volumetric differences and Dice similarity coefficients (DSCs) were calculated.

RESULTS

For both applicator types, the combination of 3D TRUS with 3D TAUS images allowed image information obscured by the shadowing artifacts under single imaging perspectives to be recovered. For the tandem-and-ring applicator, the mean ± one standard deviation (SD) TREs from the images with increasing thicknesses were 1.37 ± 1.35 mm, 1.84 ± 1.22 mm, and 1.60 ± 1.00 mm. Similarly, for the tandem-and-ovoids applicator, the mean ± SD TREs from the images with increasing thicknesses were 1.37 ± 0.35 mm, 1.95 ± 0.90 mm, and 1.61 ± 0.76 mm. No statistically significant difference was detected in the TREs for the three thicknesses for either applicator type. The mean volume differences for the bladder segmentations were 3.14% and 2.33% and mean DSCs were 87.8% and 87.7% for the tandem-and-ring and tandem-and-ovoids applicators, respectively.

CONCLUSIONS

In this proof-of-concept study, we demonstrated the feasibility of fusing 3D TRUS and 3D TAUS images based on the geometry of tandem-and-ring and tandem-and-ovoids applicators. This represents a step toward an accessible and low-cost 3D imaging method for gynecologic brachytherapy, with the potential to extend this approach to other intracavitary configurations and hybrid applicators.

Red Blood Cell Transfusion Practices for Patients With Cervical Cancer Undergoing Radiotherapy

IMPORTANCE

Packed red blood cell (PRBC) transfusions are used to treat anemia in patients with cervical cancer undergoing radiotherapy (RT) owing to concerns of hypoxia-induced radioresistance. In the absence of high-quality evidence informing transfusion practices for patients receiving external beam RT (EBRT) and brachytherapy, various arbitrary hemoglobin target levels are used worldwide.

OBJECTIVE

To develop consensus statements to guide PRBC transfusion practices in patients with cervical cancer receiving curative-intent RT with EBRT and brachytherapy.

DESIGN, SETTING, AND PARTICIPANTS

This international Delphi consensus study was completed between November 1, 2019, and July 31, 2020. A total of 63 international clinical experts in gynecologic radiation oncology were invited; 39 (62%) accepted and consented to participate. Consensus building was achieved using a 3-round anonymous Delphi consensus method. Participants rated their agreement or disagreement with statements using a 5-point Likert scale. An a priori threshold of 75% or more was required for consensus.

MAIN OUTCOMES AND MEASURES

The preplanned primary outcome of this study was to assess hemoglobin transfusion thresholds and targets for both EBRT and brachytherapy by expert consensus.

RESULTS

Response rates of 100% (39 of 39), 92% (36 of 39), and 97% (35 of 36) were achieved for the first, second, and third rounds of surveys, respectively. Twenty-three experts (59%) practiced in Canada, 11 (28%) in the United States, 3 (8%) in South America, 1 (3%) in Europe, and 1 (3%) in Asia. Consensus was reached for 44 of 103 statements (43%), which were combined to form the final 27-statement consensus guideline. No specific hemoglobin transfusion threshold was agreed on by consensus for EBRT or brachytherapy. By consensus (89% [31 of 35]), a hemoglobin transfusion target for patients who receive a PRBC transfusion should be 9 g/dL or more and less than 12 g/dL.

CONCLUSIONS AND RELEVANCE

This study presents the first international expert consensus guideline informing PRBC transfusion practices for patients with cervical cancer undergoing EBRT and brachytherapy. A minimum hemoglobin transfusion target of 9 g/dL was endorsed to balance tumor radiosensitivity with appropriate use of a scarce resource. Randomized clinical trials are required to evaluate the optimal transfusion threshold and target that maximize clinical benefit in this patient population.

Opioid therapy vs. multimodal analgesia in head and neck Cancer (OPTIMAL-HN): study protocol for a randomized clinical trial

Background

Radiation-induced mucositis (RIM) pain confers substantial morbidity for head and neck cancer (HNC) patients undergoing radiotherapy alone (RT) or chemoradiotherapy (CRT), often reducing treatment compliance. However, no standard currently exists for the treatment of RIM, and high dose opioid therapy, with its associated side effects and increased risk for chronic opioid use, remains the cornerstone of HNC pain management. The goal of this randomized clinical trial is to compare multimodal analgesia using analgesic medications with different mechanisms of action, to the institutional standard of opioid analgesia alone, in order to ascertain the optimal analgesic regimen for the management of RIM pain in HNC patients.

Methods

In this open-label, single-institution, non-inferiority, randomized clinical trial, sixty-two patients with mucosal head and neck malignancies treated with curative-intent radiation will be randomized in a 1:1 ratio, stratified by RT or CRT, between Arm 1: opioid analgesia alone as per the institutional standard, or Arm 2: multimodal analgesia using Pregabalin, Acetaminophen, and Naproxen, in addition to opioids, if required. The primary endpoint is the average 11-Numeric Rating Scale (11-NRS) score for pain during the last week of radiation treatment. Secondary endpoints include: average weekly opioid use, duration of opioid requirement, average daily 11-NRS score for pain, average weekly opioids dispensed, quality of life, hospitalizations for analgesic medication-induced complications, time to feeding tube insertion, weight loss, toxicity, treatment interruptions, and death within 3 months of completing RT treatment. Patients are eligible once analgesia is required for moderate 4/10 pain.

Discussion

This study will assess the efficacy and safety of multimodal analgesia and its impact on opioid requirements, clinical outcomes, and quality of life, as a potential new standard treatment for RIM pain in HNC patients undergoing definitive RT or CRT.

Trial registration

ClinicalTrials.gov Identifier: NCT04221165. Date of registration: January 9, 2020. Appendix 2 reports the World Health Organization trial registration dataset.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12904-021-00735-0.

Practical considerations for prostate hypofractionation in the developing world

External beam radiotherapy is an effective curative treatment option for localized prostate cancer, the most common cancer in men worldwide. However, conventionally fractionated courses of curative external beam radiotherapy are usually 8-9 weeks long, resulting in a substantial burden to patients and the health-care system. This problem is exacerbated in low-income and middle-income countries where health-care resources might be scarce and patient funds limited. Trials have shown a clinical equipoise between hypofractionated schedules of radiotherapy and conventionally fractionated treatments, with the advantage of drastically shortening treatment durations with the use of hypofractionation. The hypofractionated schedules are supported by modern consensus guidelines for implementation in clinical practice. Furthermore, several economic evaluations have shown improved cost effectiveness of hypofractionated therapy compared with conventional schedules. However, these techniques demand complex infrastructure and advanced personnel training. Thus, a number of practical considerations must be borne in mind when implementing hypofractionation in low-income and middle-income countries, but the potential gain in the treatment of this patient population is substantial.

Modern treatment outcomes for early T-stage oropharyngeal cancer treated with intensity-modulated radiation therapy at a tertiary care institution

Background

Transoral surgery (TOS), particularly transoral robotic surgery (TORS) has become the preferred modality in the United States for the treatment of early stage oropharyngeal cancer, largely due to assumptions of fewer toxicities and improved quality of life compared to primary radiotherapy (RT). However, these assumptions are based on retrospective analysis, a subset of which utilize primary RT groups not limited to T1-2 stage tumors for which transoral robotic surgery is FDA approved. Thus, there is potential for underestimating survival and overestimating toxicity, including treatment related mortality, in primary RT.

Methods

Consecutive cases of early T-stage (T1–T2) oropharyngeal cancer presenting to the London Health Sciences Centre between 2014 and 2018 treated with RT or chemoradiation (CRT) were reviewed. Patient demographics, treatment details, survival outcomes and toxicity were collected. Toxicities were retrospectively graded using the Common Terminology Criteria for Adverse Events criteria.

Results

A total of 198 patients were identified, of which 82% were male and 73% were HPV-positive. Sixty-eight percent of patients experienced a grade 2 toxicity, 48% a grade 3 and 4% a grade 4. The most frequent toxicities were dysphagia, neutropenia and ototoxicity. The rates of gastrostomy tube dependence at 1 and 2 years were 2.5% and 1% respectively. There were no grade 5 (fatal) toxicities. HPV-positive patients experienced improved 5-year overall survival (86% vs 64%, p = 0.0026).

Conclusions

Primary RT or CRT provides outstanding survival for early T-stage disease, with low rates of severe toxicity and feeding tube dependence. This study provides a reference for comparison for patients treated with primary transoral surgery.

3D image-guided interstitial brachytherapy for primary vaginal cancer: A multi-institutional experience

PURPOSE/OBJECTIVES

High dose rate (HDR) interstitial brachytherapy (ISBT) boost is integral for definitive radiation treatment of primary vaginal cancer. Technological advances with CT or MRI guidance provide improved precision and ability to treat more extensively invasive tumors over historical techniques, but reported experience is limited. We sought to provide updated outcome and toxicity data for women with primary vaginal cancer undergoing treatment with a modern ISBT technique.

MATERIAL/METHODS

Databases of primary vaginal carcinoma patients treated at two Canadian academic cancer institutions were combined including patient, tumor and treatment characteristics, and survival outcomes and toxicity data. Descriptive statistics, survival estimates based on the Kaplan-Meier method, and univariable/multivariable Cox proportional hazards regression analyses are reported.

RESULTS

Between 2002 and 2017, 67 women with primary vaginal cancer were treated with 3D HDR ISBT. FIGO stage distribution was I (22.4%), II (50.8%), III (17.9%), IVa (9.0%). All patients received external beam radiotherapy and HDR ISBT of 500-750 cGy per fraction over 2-4 fractions. Median follow-up was 2.68 years (95% confidence interval: 2.04-6.04). Cumulative rate of grade 3-4 genitourinary/gastrointestinal toxicity was 10.4%. Four patients developed vaginal fistula. Progression-free survival at 2 and 3 years was 73.5% and 66.4% for all patients, 78.3% and 75.0% for stage I-II and 61.6% and 46.2% for stage III-IVa, respectively (log-rank p = 0.252).

CONCLUSIONS

Use of 3D image-guided HDR ISBT boost was safe and resulted in improved survival outcomes compared to historical rates in this series of primary vaginal cancer patients. Prospective study is warranted to better define clinical and dosimetric predictors of local control.

Immune cell profiling in Gleason 9 prostate cancer patients treated with brachytherapy versus external beam radiotherapy: An exploratory study

This exploratory study evaluates immunological changes in high-risk Gleason 9 prostate cancer patients treated with EBRT+BT compared to EBRT alone. Notably, BT demonstrates the potential to elicit a T cell response which may support further investigation using circulating immune cells as predictive and prognostic biomarkers for radiotherapy response.

Is hypofractionated whole pelvis radiotherapy (WPRT) as well tolerated as conventionally fractionated WPRT in prostate cancer patients? The HOPE trial

BACKGROUND

Patients with high-risk prostate cancer are at increased risk of lymph node metastasis and are thought to benefit from whole pelvis radiotherapy (WPRT). There has been recent interest in the use of hypofractionated radiotherapy in treating prostate cancer. However, toxicity and cancer outcomes associated with hypofractionated WPRT are unclear at this time. This phase II study aims to investigate the impact in quality of life associated with hypofractionated WPRT compared to conventionally fractionated WPRT.

METHODS

Fifty-eight patients with unfavourable intermediate-, high- or very high-risk prostate cancer will be randomized in a 1:1 ratio between high-dose-rate brachytherapy (HDR-BT) + conventionally fractionated (45 Gy in 25 fractions) WPRT vs. HDR-BT + hypofractionated (25 Gy in 5 fractions) WPRT. Randomization will be performed with a permuted block design without stratification. The primary endpoint is late bowel toxicity and the secondary endpoints include acute and late urinary and sexual toxicity, acute bowel toxicity, biochemical failure-, androgen deprivation therapy-, metastasis- and prostate cancer-free survival of the hypofractionated arm compared to the conventionally fractionated arm.

DISCUSSION

To our knowledge, this is the first study to compare hypofractionated WPRT to conventionally fractionated WPRT with HDR-BT boost. Hypofractionated WPRT is a more attractive and convenient treatment approach, and may become the new standard of care if demonstrated to be well-tolerated and effective.

TRIAL REGISTRATION

This trial was prospectively registered in ClinicalTrials.gov as NCT04197141 on December 12, 2019.

Preservation of swallowing in resected oral cavity squamous cell carcinoma: examining radiation volume effects (PRESERVE): study protocol for a randomized phase II trial

BACKGROUND

Patients with resected oral cavity squamous cell carcinoma (OCSCC) are often treated with adjuvant radiation (RT) ± concomitant chemotherapy based on pathological findings. Standard RT volumes include all surgically dissected areas, including the tumour bed and dissected neck. RT has significant acute and long-term toxicities including odynophagia, dysphagia, dermatitis and fibrosis. The goal of this study is to assess the rate of regional failure with omission of radiation to the surgically dissected pathologically node negative (pN0) hemi-neck(s) compared to historical control, and to compare oncologic outcomes, toxicity, and quality of life (QoL) profiles between standard RT volumes and omission of RT to the pN0 neck.

METHODS

This is a multicentre phase II study randomizing 90 patients with T1-4 N0-2 OCSCC with at least one pN0 hemi-neck in a 1:2 ratio between standard RT volumes and omission of RT to the pN0 hemi-neck(s). Patients will be stratified based on overall nodal status (nodal involvement vs. no nodal involvement) and use of concurrent chemotherapy. The primary endpoint is regional failure in the pN0 hemi-neck(s); we hypothesize that a 2-year regional recurrence of 20% or less will be achieved. Secondary endpoints include overall and progression-free survival, local recurrence, rate of salvage therapy, toxicity and QoL.

DISCUSSION

This study will provide an assessment of omission of RT to the dissected pN0 hemi-neck(s) on oncologic outcomes, QoL and toxicity. Results will inform the design of future definitive phase III trials.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT03997643 . Date of registration: June 25, 2019, Current version: 2.0 on July 11 2020.

Should we embrace hypofractionated radiotherapy for cervical cancer? A technical note on management during the COVID-19 pandemic

Cervical cancer is a deadly disease and the COVID-19 pandemic has the potential to further impact its lethality. Hypofractionated radiotherapy could mitigate this impact, however robust data in cervical cancer setting still is lacking. Information provided here could help institutions in reducing radiotherapy fractions for cervical cancer patients.

Does ADT benefit unfavourable intermediate risk prostate cancer patients treated with brachytherapy boost and external beam radiotherapy? A propensity-score matched analysis

PURPOSE

To investigate the role of androgen deprivation therapy (ADT) in unfavorable intermediate risk (UIR) prostate cancer patients treated with high-dose rate (HDR) brachytherapy (BT) boost.

MATERIAL AND METHODS

Data from 326 consecutive NCCN UIR prostate cancer patients treated in a single institution from 2009 to 2016 with 15 Gy HDR-BT boost plus 37.5 Gy external beam radiotherapy (EBRT) in 15 fractions to prostate and proximal seminal vesicles were retrospectively collected. Baseline information was collected and patients receiving vs. not receiving ADT were matched using a propensity-score model. Primary endpoint was biochemical-failure-free survival (BFFS). Kaplan-Meier estimates and stratified log-rank tests (adjusting for matched design) were used to compare BFFS, castration-resistance (CRFS) and metastasis free survival (MFS) outcomes between both groups.

RESULTS

A total of 326 patients were included in the analysis of which 52 ADT patients were matched to 104 non-ADT patients in a 1:2 ratio. Median follow-up was 3.4 years and 5.5 years for ADT and non-ADT respectively. No significant baseline differences were observed. ADT was used for a median total time of 6 months (interquartile range [IQR]: 4-6) and delivered a median time of 2.7 months (IQR: 1.7-4.3) prior to HDR-BT. BFFS was significantly improved in the ADT group (stratified log-rank: p = 0.043) with 3-year and 6-year BFFS of 98% and 90% for the ADT group and 92% and 82% for the non-ADT group, respectively. No significant differences were detected for CRFS or MFS.

CONCLUSION

Short-term ADT increased BFFS in UIR prostate cancer patients treated with HDR-BT boost plus EBRT.

Stereotactic Ablative Radiotherapy for Recurrent or Metastatic Gynecological Cancer: Extending Lives?

OPINION STATEMENT

Recent phase II clinical trials suggest that stereotactic ablative radiation therapy (SABR) can potentially improve survival for patients with oligometastatic cancer. However, these studies have mostly enrolled primaries other than gynecologic malignancies. While level I evidence is limited, recent publications exploring the use of SABR for oligometastatic gynecologic cancers have indicated a potential role for this treatment in para-aortic lymph node recurrences, and in visceral and brain metastases. The use of SABR for recurrences in the pelvis presents a number of challenges as these patients have often received previous radiation treatment. In these settings, care must be taken to avoid trespassing normal tissue tolerance with SABR leading to toxicity, especially as the potential benefit of SABR in this setting is not based on high-level evidence. Although SABR is feasible and in general safe for oligometastatic gynecologic malignancies, insufficient data are available to indicate whether it is associated with improved survival. Clinical judgment that incorporates patient and tumor factors is needed to determine if SABR is appropriate for selecting patients. Future directions include combining SABR with novel systemic therapies, determining optimal sequencing of treatments, and generating more robust randomized data pertaining to the use of SABR for oligometastatic gynecologic cancers.

A Novel Salvage Option for Local Failure in Prostate Cancer, Reirradiation Using External Beam or Stereotactic Radiation Therapy: Systematic Review and Meta-Analysis

Purpose

Reirradiation (re-RT) using external beam radiation therapy (EBRT) is a novel salvage strategy for local failure in prostate cancer. We performed a systematic review describing oncologic and toxicity outcomes for salvage EBRT/stereotactic radiation therapy (SBRT) re-RT.

Methods and Materials

A International Prospective Register of Systematic Reviews registered (#141466) systematic review, meta-analysis, and meta-regression was conducted using preferred reporting items for systematic reviews and meta-analyses guidelines. PubMed and EMBASE were searched from inception through September 2019. Outcome measures included local control (LC), biochemical relapse free survival (BRFS), and ≥grade 3 genitourinary (GU)/gastrointestinal (GI) toxicity. EBRT and SBRT data were collected separately. Meta-regression explored disease and toxicity outcomes as a function of equivalent dose in 2 Gy fractions (EQD2), length of follow-up, and partial versus whole prostate reirradiation.

Results

Nineteen studies representing 13 cohorts were included (428 patients). Weighted mean follow-up was 26.1 months. Median re-RT EQD2 was 77.1 Gy (α/β = 1.5), with 92% of patients receiving SBRT, 52.1% of patients receiving partial prostate re-RT, and 30.1% of patients receiving androgen deprivation therapy with re-RT. LC was 83.2% (95% confidence interval [CI], 75.5%-90.9%) and BRFS was 59.3% (47.9%-70.7%). Reported late toxicity ≥grade 3 was 3.4% (95% CI, 1.0%-5.8%) for GU and 2.0% (95% CI, 0.1%-4.0%) for GI. Meta-regression found higher LC, BRFS, and reported GU/GI toxicity with increasing EQD2, with partial prostate re-RT associated with less reported GU/GI toxicity and no detriment to LC and BRFS.

Conclusions

Salvage re-RT using EBRT, particularly with SBRT, is an emerging technique to treat isolated local failure of prostate cancer. With short-term follow-up, LC, BRFS, and reported toxicities appear reasonable, although further follow-up is required before definitive statements on late toxicities can be made. Our review is limited by incomplete reporting of androgen deprivation therapy use in the primary literature. Further prospective studies and longer follow-up are needed before considering re-RT as standard practice.

Comparison of CTVHR and organs at risk contours between TRUS and MR images in IB cervical cancers: a proof of concept study

Purpose

To compare CTV_HR and OAR dimensions and inter-rater agreement between magnetic resonance (MR) and trans-rectal ultrasound (TRUS) images in IB cervical cancer patients.

Methods

IB cervical cancer patients treated with (chemo)radiotherapy plus MR-guided brachytherapy (BT) were prospectively enrolled in this study. Radiation oncologists contoured CTV_HR and OARs in pre-BT MR images (MRI) and intra-operative TRUS images. These contours were subsequently compared in regard to volume and dimension. Contour inter-rater agreement analysis was also investigated using kappa index (KI). Stata 15.0 was used for statistical analysis and a p-value < 0.05 was considered statistically significant.

Results

TRUS CTV_HR volumes were statistically smaller than the respective MRI contoured volumes. TRUS CTV_HR thickness was found to be consistently smaller than MRI contours in all patients. No statistical difference was seen in width and height between the two different imaging modalities. MRI contours had a median KI of 0.66 (range: 0.56–0.77) while TRUS-based contours had a median KI of 0.64 (range: 0.47–0.77). Bladder and rectum had very satisfactory KI in both imaging modalities. Vaginal contours had moderate agreement in MR (0.52) and in TRUS images (0.58).

Conclusion

TRUS images allow good visualization of CTV_HR and OARs in IB cervical cancer patients. Inter-rater contour variability was comparable between TRUS and MR images. TRUS is a promising modality on its own for image-guided BT.

Results of 15 Gy HDR-BT boost plus EBRT in intermediate-risk prostate cancer: Analysis of over 500 patients

PURPOSE/OBJECTIVE

To report biochemical control associated with single fraction 15 Gy high-dose-rate brachytherapy (HDR-BT) boost followed by external beam radiation (EBRT) in patients with intermediate-risk prostate cancer.

MATERIALS AND METHODS

A retrospective chart review of all patients with intermediate-risk disease treated with a real-time ultrasound-based 15 Gy HDR-BT boost followed by EBRT between 2009 and 2016 at a single quaternary cancer center was performed. Freedom from biochemical failure (FFBF), cumulative incidence of androgen deprivation therapy use for biochemical or clinical failure post-treatment (CI of ADT) and metastasis-free survival (MFS) outcomes were measured.

RESULTS

518 patients met the inclusion criteria for this study. Median age at HDR-BT was 67 years (IQR 61-72). 506 (98%) had complete pathologic information available. Of these, 146 (28%) had favorable (FIR) and 360 (69%) had unfavorable (UIR) intermediate-risk disease. 83 (16%) received short course hormones with EBRT + HDR. Median overall follow-up was 5.2 years. FFBF was 91 (88-94)% at 5 years. Five-year FFBF was 94 (89-99)% and 89 (85-94)% in FIR and UIR patients, respectively (p = 0.045). CI of ADT was 4 (2-6)% at 5 years. Five-year CI of ADT was 1 (0-3)% and 5 (2-8)% in FIR and UIR patients, respectively (p = 0.085). MFS was 97 (95-98)% at 5 years. Five-year MFS was 100 (N/A-100)% and 95 (92-98)% in FIR and UIR patients, respectively (p = 0.020).

CONCLUSION

In this large cohort of intermediate-risk prostate cancer patients, 15 Gy HDR-BT boost plus EBRT results in durable biochemical control and low rates of ADT use for biochemical failure.

Absolute percentage of biopsied tissue positive for Gleason pattern 4 disease (APP4) appears predictive of disease control after high dose rate brachytherapy and external beam radiotherapy in intermediate risk prostate cancer

BACKGROUND AND PURPOSE

To identify if, in intermediate risk prostate cancer (IR-PCa), the absolute percentage of biopsied tissue positive for pattern 4 disease (APP4) may be a predictor of outcome.

MATERIALS AND METHODS

411 patients with IR-PCa were retrospectively reviewed. APP4 was calculated based on biopsy reports. Multivariable competing risk analysis was then performed on optimized APP4 cutpoints to predict for biochemical failure (BF), androgen deprivation use for BF (ADT-BF) and development of metastases (MD).

RESULTS

Median follow-up for the cohort was 5.2 (Inter Quartile Range: 2.9-6.6) years. Median baseline PSA was 7.3 (5.3-9.8) ng/mL. 234 (56.9%) patients had T1 and 177 (43.1%) had T2 disease. Median APP4 was 2.00 (0.75-7.50)%. 38 (9.3%) patients experienced BF. The optimal cutpoint of APP4 for BF was >3.3% with an area under the curve (AUC) of 0.66. 17 (4.1%) received ADT-BF. The ADT-BF cutpoint was >6.6% with an AUC of 0.72. Eight (2.0%) developed MD. The MD cutpoint was >17.5% with an AUC of 0.86. Using APP4 >3.3 vs ≤ 3.3, log-transformed baseline PSA ln(PSA) (HR 2.5, 1.1-6.1; p = 0.037) and APP4 (HR 2.3, 1.1-4.7; p = 0.031) predicted for BF. Using APP4 >6.6 vs ≤ 6.6, ln(PSA) (HR 4.2, 1.4-12.4; p = 0.010) and APP4 (HR 3.7, 1.4-10.0; p = 0.009) were predictive of ADT-BF. APP4 >17.5 vs ≤ 17.5 alone was predictive of MD (HR 25.7, 4.9-135.3; p < 0.001).

CONCLUSION

APP4 cutpoints of >3.3%, >6.6% and >17.5% were strongly associated with increased risk of BF, ADT-BF and developing MD respectively. These findings may inform future practice when treating IR-PCa but require external validation.

Optimized penile surface mold brachytherapy using latest stereolithography techniques: A single-institution experience

PURPOSE

To describe a technique of penile surface mold high-dose-rate (HDR) brachytherapy and early outcomes.

METHODS AND MATERIALS

Five patients diagnosed with a T1aN0 squamous cell carcinoma of the penis were treated using a penile surface mold HDR brachytherapy technique. A negative impression of the penis was obtained using dental alginate. CT images were acquired of the penile impression; subsequently, a virtual model of the patient's penis was generated. The positive model was imported into a computer-assisted design program where catheter paths were planned such that an optimized offset of 5 mm from the penile surface was achieved. The virtual model was converted into a custom applicator. A total dose of 40 Gy was delivered in 10 fractions. Patients were followed at 1, 3, 6, and 12 months after treatment and then every 6 months thereafter. Toxicities were reported using Common Terminology Criteria for Adverse Events v4.0.

RESULTS

All patients tolerated treatment well. Acute Grade 2 skin reactions were observed within the first month after treatment. Median followup was 35 months. Late Grade 1 skin toxicities were observed. One patient experienced a urethral stricture requiring dilatation. Two patients developed local recurrence.

CONCLUSION

This technique allows the delivery of penile HDR brachytherapy as an outpatient procedure with minimal discomfort to the patient during each application and is a repeatable and accurate setup. This technique warrants validation in larger series with longer followup.

Prospective evaluation of pretreatment and intratreatment FDG PET-CT SUV stability in primary head and neck cancer

PURPOSE

To evaluate standardized uptake value (SUV) stability on pretreatment and intratreatment 18-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) in patients undergoing definitive CRT for head and neck cancer (HNC).

METHODS

Primary tumor and nodal volumes of interest (VOIs) from HNC patients were contoured on the pretreatment and intratreatment PET-CT by two independent observers. SUV stability was measured with intersection calculations (DICE, overlap fraction, center to center) between the VOIs at threshold levels of 50%, 60%, 70%, 80%, and 90% of the SUV maximum.

RESULTS

The mean calculated DICE of the 50%, 60%, 70%, 80%, 90% SUV threshold was 0.53, 0.48, 0.41, 0.28, and 0.12, respectively. The mean calculated overlap fraction was 0.71, 0.65, 0.58, 0.43, and 0.2, respectively. Center-center difference demonstrates spatial variability of 7.8, 8.2, 8.6, 9.5, and 11.2 mm for these SUV subvolumes of interest.

CONCLUSIONS

HNC subvolumes defined by SUV thresholding technique in FDG PET-CT imaging do not remain physically stable during (chemo)RT.

HIGHLIGHTS

All pretreatment and intratreatment SUV thresholds (50%-90%) overlap indexes are low during the course of (chemo)radiation. Pretreatment and intratreatment center to center variation further corroborates that all FDG threshold volumes do not remain stable during treatment. No difference in SUV threshold stability was seen between p16 positive and negative tumors.

Synchronous anal canal carcinoma in a heterosexual couple

Background

Sexually transmitted Human Papilloma Virus (HPV) infection is a known risk factor for cancer of the anal canal in both men and women.

Case presentation

We describe a report of synchronous carcinoma of the anal canal in a heterosexual couple. High risk type 16 HPV DNA was detected in both tumors.

Conclusion

Longstanding sexual partners may share risk of HPV-associated anal canal cancer.

Evaluation of a new predictor of heart and left anterior descending artery dose in patients treated with adjuvant radiotherapy to the left breast

Background

Heart-sparing techniques are time and resource intensive, although not all patients require the use of these strategies. This study evaluates the performance of different distance metrics in predicting the need for breath-hold radiotherapy in left-sided breast cancer patients receiving adjuvant radiotherapy.

Methods

Fifty left-sided breast cancer patients treated with breast conserving surgery and adjuvant radiotherapy to the breast from a single institution were retrospectively studied. The left breast and organs at risk were contoured in accordance to guidelines and a plan with tangents was obtained using the free-breathing CT in supine position. Heart (mean heart dose (MHD), heart V25 Gy) and left anterior descending artery dosimetry were computed and compared against distance metrics under investigation (Contact Heart, 4th Arch and 5th Arch). Recursive partitioning analysis (RPA) was used to determine optimal cut-points for distance metrics for dosimetric end points. Receiver operating characteristic curves and Pearson correlation coefficients were used to evaluate the association between distance metrics and dosimetric endpoints. Univariable and multivariable logistic regression analysis was performed to identify significant predictors of dosimetric end points.

Results

The mean MHD and heart V25 Gy were 2.3 Gy and 10.4 cm³, respectively. With tangents, constraints for MHD (< 1.7 Gy and V25 Gy < 10 cm³) were unattainable in 80% and 46% of patients, respectively. Optimal RPA thresholds included: Contact Heart (73 mm), 4th Arch (7 mm) and 5th Arch (41 mm). Of these, the 4th Arch had the highest overall accuracy, sensitivity, concordance index and correlation coefficient. All metrics were statistically significant predictors for MHD ≥ 1.7 Gy based on univariable logistic regression. Fifth Arch did not reach significance for heart V25 Gy ≥ 10 cm³. Fourth Arch was the only predictor to remain statistically significant after multivariable analysis.

Conclusions

We propose a novel “4th Arch” metric as an accurate and practical tool to determine the need for breath-hold radiotherapy for left-sided breast cancer patients undergoing adjuvant radiotherapy with standard tangents. Further validation in an external cohort is necessary.

High dose-rate brachytherapy in the treatment of prostate cancer

High dose-rate (HDR) brachytherapy involves delivery of a high dose of radiation to the cancer with great sparing of surrounding organs at risk. Prostate cancer is thought to be particularly sensitive to radiation delivered at high dose-rate or at high dose per fraction. The rapid delivery and high conformality of dose results in lower toxicity than that seen with low dose-rate (LDR) implants. HDR combined with external beam radiotherapy results in higher cancer control rate than external beam only, and should be offered to eligible high and intermediate risk patients. While a variety of dose and fractionations have been used, a single 15 Gy HDR combined with 40-50 Gy external beam radiotherapy results in a disease-free survival of over 90% for intermediate risk and 80% for high risk. HDR monotherapy in two or more fractions (e.g., 27 Gy in 2 fractions or 34.5 Gy in 3) is emerging as a viable alternative to LDR brachytherapy for low and low-intermediate risk patients, and has less toxicity. The role of single fraction monotherapy to a dose of 19-20 Gy is evolving, with some conflicting data to date. HDR should also be considered as a salvage approach for recurrent disease following previous external beam radiotherapy. A particular advantage of HDR in this setting is the ease of delivering focal treatments, which combined with modern imaging allows focal dose escalation with minimal toxicity. Trans-rectal ultrasound (TRUS) based planning is replacing CT-based planning as the technique of choice as it minimizes or eliminates the need to move the patient between insertion, planning and treatment delivery, thus ensuring high accuracy and reproducibility of treatment.

Pattern of relapse and dose received by the recurrent intraprostatic nodule in low- to intermediate-risk prostate cancer treated with single fraction 19 Gy high-dose-rate brachytherapy

PURPOSE

The purposes of this study were to investigate the pattern of relapse in patients with low- or intermediate-risk prostate cancer treated with 19-Gy high-dose-rate brachytherapy (HDR-BT) and to calculate the dose received by the area of recurrence.

METHODS AND MATERIALS

Patients included in this analysis were treated under a Phase II randomized trial that evaluated the role of 19-Gy HDR-BT monotherapy in low- and intermediate-risk prostate cancers. Multiparametric prostate MRI and prostate biopsy were performed in patients with suspicious local recurrence. The site of local relapse was compared with the initial site of disease. The dose received by the site of recurrence was investigated through registration of the posttreatment multiparametric prostate MRI with the HDR-BT treatment plan.

RESULTS

Eight of 87 treated patients were found to have local recurrence after 19-Gy HDR-BT. Seven of the eight recurrences were at the site of initial bulk disease. Seven patients were found to have a more aggressive histology in the posttreatment biopsy. The mean volume of prostate that had received 100% of prescription dose was 97%. Mean dose to area of recurrence was 29.1 Gy, whereas dose to 98% and dose to 90% of the recurrence were 21.6 Gy and 23.2 Gy, respectively.

CONCLUSIONS

The relapse pattern after a single 19-Gy HDR-BT is predominantly associated with the site of initial disease. This lends some rationale to future strategies of further focused dose escalation to initial site of disease, notwithstanding the fact that the calculated biologically equivalent dose using linear-quadratic assumptions is already very high.

Cancer Deaths due to Lack of Universal Access to Radiotherapy in the Brazilian Public Health System

AIMS

Radiotherapy plays a fundamental role in the treatment of cancer. Currently, the Brazilian public health system cannot match the national radiotherapy demand and many patients requiring radiotherapy are never exposed to this treatment. This study estimated the number of preventable deaths in the public health system if access to radiotherapy was universal.

MATERIALS AND METHODS

Incidence rates for the year 2016 provided by Instituto Nacional de Cancer were used in this analysis. The number of untreated patients requiring radiotherapy was obtained through the difference between the total number of patients requiring radiotherapy and the total amount of delivered radiotherapy treatments in the public health system. The number of deaths for the three most common cancers in each gender due to radiotherapy shortage was calculated. Initially, the total number of patients per cancer type was divided in stages using Brazilian epidemiological data. Subsequently, previously published tree arm diagrams were used to define the rate of patients requiring radiotherapy in each specific clinical setting. Finally, the clinical benefit of radiotherapy in overall survival was extracted from studies with level 1 evidence.

RESULTS

Over 596 000 cancer cases were expected in Brazil in 2016. The public health system covers more than 75% of the Brazilian population and an estimated 111 432 patients who required radiotherapy in 2016 did not receive this treatment. Breast, colorectal and cervix cancers are the most frequent malignant tumours in women and prostate, lung and colorectal in men. The number of deaths due to a radiotherapy shortage in the year 2016 for these types of cancer were: (i) breast: 1011 deaths in 10 years; (ii) cervix: 2006 deaths in 2 years; (iii) lung: 1206 deaths in 2 years; (iv) prostate, intermediate risk: 562 deaths in 13 years; high risk: 298 deaths in 10 years; (v) colorectal: 0 deaths, as radiotherapy has no proven benefit in overall survival.

CONCLUSION

Thousands of cancer patients requiring radiotherapy do not have access to this treatment in the Brazilian public health system. The shortage of radiotherapy has a significant detrimental effect on cancer survival; over 5000 deaths would probably be prevented in the most common cancer types if radiotherapy access was universal.

Dosimetric comparison of interstitial brachytherapy with multi-channel vaginal cylinder plans in patients with vaginal tumors

BACKGROUND

To evaluate the dosimetric performance of multi-channel vaginal cylinder (MCVC) against interstitial brachytherapy (ISBT) for the treatment of vaginal tumors.

METHODS

Vaginal tumors with extension of > 0.5 cm and ≤ 2 cm from the lateral vaginal wall and/or ≤ 1 cm in height above the vaginal vault were retrospectively selected from a ISBT registry trial database. The selected patients were treated with ISBT and targets included the intermediate (IRCTV) or high-risk (HRCTV) clinical target volumes. For technique comparison, a 35 mm MCVC was registered with the interstitial intra-vaginal cylinder. Bladder and rectum contours were transferred from the ISBT to the MCVC-BT plans. Vaginal mucosa was achieved by 3 mm uniform expansion from cylinder surface. Both the ISBT and MCVC-BT plans were optimized using the Inverse Planning Simulated Annealing optimization algorithm. After normalizing target D90 to 700 cGy, dose to organs at risk were measured and compared between ISBT and MCVC plans.

RESULTS

Six interstitial patient plans met the inclusion criteria for this study. Four patients had vaginal primaries and two recurrent cancers in the vagina. Lower doses to bladder and rectum were seen with ISBT plans. In half of the MCVC plans, the rectal dose met the recommended constraints. For plans in which the rectal constraint was not met, the target volumes were abutting the rectum and had a cranial-caudal length ≥ 5 cm. Dose to vaginal mucosa was lower in ISBT plans directed to the HRCTVs, although no difference was seen in circumferential IRCTVs.

CONCLUSIONS

Overall, ISBT results in decreased dose to OARs as compared to MCVC. However, MCVC BT results in acceptable doses to OARs with possible improvement in vaginal doses for circumferential targets. Careful consideration to tumor geometry and location may help guide optimal techniques in vaginal tumor brachytherapy.

Quality of life in responders after palliative radiation therapy for painful bone metastases using EORTC QLQ-C30 and EORTC QLQ-BM22: results of a Brazilian cohort

BACKGROUND

Bone metastases cause pain, suffering and impaired quality of life (QoL). Palliative radiotherapy (RT) and/or chemotherapy are effective methods in controlling pain, reducing analgesics use and improving QoL. This study goal was to investigate the changes in QoL scores among patients who responded to palliative treatment.

METHODS

A prospective study evaluating the role of radiation therapy in a public academic hospital in São Paulo-Brazil recorded patients' opioid use, pain score, Portuguese version of QLQ-BM22 and QLQ-C30 before and 2 months after radiotherapy. Analgesic use and pain score were used to calculate international pain response category. Overall response was defined as the sum of complete response (CR) and partial response (PR). CR was defined as pain score of 0 with no increase in analgesic intake whereas PR was defined as pain reduction ≥2 without analgesic increase or analgesic reduction in ≥25% without increase in pain at the treated site.

RESULTS

From September 2014 to October 2015, 25 patients with bone metastases responded to RT or chemotherapy (1 CR, 24 PR). There were 8 male and 17 female patients. The median age of the 25 patients was 59 (range, 22 to 80) years old. Patient's primary cancer site was breast [11], prostate [5], lung [2], others [7]. For QLQ-BM 22, the mean scores of 4 categories at baseline were: pain site (PS) 39, pain characteristics (PC) 61, function interference (FI) 49 and psycho-social aspects (PA) 57. At 2 month follow up, the scores were PS 27, PC 37, FI 70 and PA 59. Statistical significant improvement (P<0.05) was seen in PS, PC, FI but not PA. In the QLQ-C30, the scores were not statistically different for all categories, except for pain that demonstrated a 33 point decrease in the median pain score domain (66 to 33).

CONCLUSIONS

Responders to RT at 2 months presented improvement in BM22 and C30 pain domains, and also improvement in functional interference domain of the BM22 questionnaire.