Radiomic- and dosiomic-based clustering development for radio-induced neurotoxicity in pediatric medulloblastoma

BACKGROUND

Texture analysis extracts many quantitative image features, offering a valuable, cost-effective, and non-invasive approach for individual medicine. Furthermore, multimodal machine learning could have a large impact for precision medicine, as texture biomarkers can underlie tissue microstructure. This study aims to investigate imaging-based biomarkers of radio-induced neurotoxicity in pediatric patients with metastatic medulloblastoma, using radiomic and dosiomic analysis.

METHODS

This single-center study retrospectively enrolled children diagnosed with metastatic medulloblastoma (MB) and treated with hyperfractionated craniospinal irradiation (CSI). Histological confirmation of medulloblastoma and baseline follow-up magnetic resonance imaging (MRI) were mandatory. Treatment involved helical tomotherapy (HT) delivering a dose of 39 Gray (Gy) to brain and spinal axis and a posterior fossa boost up to 60 Gy. Clinical outcomes, such as local and distant brain control and neurotoxicity, were recorded. Radiomic and dosiomic features were extracted from tumor regions on T1, T2, FLAIR (fluid-attenuated inversion recovery) MRI-maps, and radiotherapy dose distribution. Different machine learning feature selection and reduction approaches were performed for supervised and unsupervised clustering.

RESULTS

Forty-eight metastatic medulloblastoma patients (29 males and 19 females) with a mean age of 12 ± 6 years were enrolled. For each patient, 332 features were extracted. Greater level of abstraction of input data by combining selection of most performing features and dimensionality reduction returns the best performance. The resulting one-component radiomic signature yielded an accuracy of 0.73 with sensitivity, specificity, and precision of 0.83, 0.64, and 0.68, respectively.

CONCLUSIONS

Machine learning radiomic-dosiomic approach effectively stratified pediatric medulloblastoma patients who experienced radio-induced neurotoxicity. Strategy needs further validation in external dataset for its potential clinical use in ab initio management paradigms of medulloblastoma.

Fully automated volumetric modulated arc therapy technique for radiation therapy of locally advanced breast cancer

BACKGROUND

This study aimed to evaluate an a-priori multicriteria plan optimization algorithm (mCycle) for locally advanced breast cancer radiation therapy (RT) by comparing automatically generated VMAT (Volumetric Modulated Arc Therapy) plans (AP-VMAT) with manual clinical Helical Tomotherapy (HT) plans.

METHODS

The study included 25 patients who received postoperative RT using HT. The patient cohort had diverse target selections, including both left and right breast/chest wall (CW) and III-IV node, with or without internal mammary node (IMN) and Simultaneous Integrated Boost (SIB). The Planning Target Volume (PTV) was obtained by applying a 5 mm isotropic expansion to the CTV (Clinical Target Volume), with a 5 mm clip from the skin. Comparisons of dosimetric parameters and delivery/planning times were conducted. Dosimetric verification of the AP-VMAT plans was performed.

RESULTS

The study showed statistically significant improvements in AP-VMAT plans compared to HT for OARs (Organs At Risk) mean dose, except for the heart and ipsilateral lung. No significant differences in V95% were observed for PTV breast/CW and PTV III-IV, while increased coverage (higher V95%) was seen for PTV IMN in AP-VMAT plans. HT plans exhibited smaller values of PTV V105% for breast/CW and III-IV, with no differences in PTV IMN and boost. HT had an average (± standard deviation) delivery time of (17 ± 8) minutes, while AP-VMAT took (3 ± 1) minutes. The average γ passing rate for AP-VMAT plans was 97%±1%. Planning times reduced from an average of 6 h for HT to about 2 min for AP-VMAT.

CONCLUSIONS

Comparing AP-VMAT plans with clinical HT plans showed similar or improved quality. The implementation of mCycle demonstrated successful automation of the planning process for VMAT treatment of locally advanced breast cancer, significantly reducing workload.

Cardiological Safety of 5-Fraction Whole Breast Irradiation

PURPOSE/OBJECTIVE(S)

Our study aims to assess heart toxic effect using a reliable cardiac assessment with standard and 3-dimensional (3D) echocardiography and left ventricular (LV) global longitudinal strain (GLS) in patients receiving a 5-fraction (total dose 26 Gy) postoperative radiation therapy (RT) for breast cancer (BC).

MATERIALS/METHODS

SAFE-FORWARD is an observational prospective cohort study (NCT04842409). Inclusion criteria were: (1) patients with invasive BC receiving ultra-hypofractionated whole breast irradiation (WBI) (26 Gy in 5 fractions) after breast conserving surgery (BCS) (2) without cardiovascular comorbidity and (3) previous thoracic irradiation. All enrolled patients are prospectively monitored for 12 months, receiving a complex cardiological assessment before RT start (baseline), and at 2-, 6-, and 12-month after RT end of treatment. Both acute and early-late toxicity are evaluated according to CTCAE (v.5) scales. The primary endpoint is defined as detection of any subclinical impairment in myocardial function and deformation (decrease ≥10%) measured with standard and 3D echocardiography and LV GLS.

RESULTS

Overall, 40 women (median age 66 years; range, 48-84) were enrolled in the study. We analyzed patients who had completed the cardiological assessment at 12 months. Baseline patient's characteristics are summarized in Table 1. All patients received ultra-hypofractionated WBI (26 Gy in 5 fractions), 25 patients also received adjuvant endocrine therapy. GLS worsened 4% or less, both for the left- and right-side treated breast, and remained in normal range for all the time points. The only exception was for RVGLS at 6 months for right-sided treatment where it reached a borderline value (-17.4±4.9 SE). 3D-LVEF remains stable during observation, both for the left- and right-side treated breast CONCLUSION: The 5-fraction schedule after BCS is well tolerated and the intensive 1-year cardiological monitoring showed no significant differences overtime in cardiac functioning.

ABBREVIATIONS

DIBH, deep inspiration breath hold; AI, aromatase inhibitors; BCCT, Breast Cancer Conservation Treatment.

Updates on the APBI-IMRT-Florence Trial (NCT02104895) Technique: From the Intensity Modulated Radiation Therapy Trial to the Volumetric Modulated Arc Therapy Clinical Practice

Several phase 3 trials have demonstrated partial breast irradiation noninferiority compared with whole breast irradiation in terms of local control and similar or reduced toxicity. During recent years, especially owing to the COVID-19 pandemic, a growing interest in 5-fraction regimens emerged. The APBI-IMRT-Florence trial (NCT02104895) schedule (30 Gy in 5 fractions) might represent an appealing treatment option, being both a safe and effective partial breast irradiation schedule, with long-term reported results. The aim of this report is to support planners interested in implementing this technique and to warrant equal access to postoperative radiation treatment for most early breast cancer patient candidates. We report the current delivery technique optimized from the original protocol and the updated dose constraints for plan optimization. We also report a statistical analysis of dosimetric parameters on 50 patients treated in consecutive fractions. Treatment-related toxic effects were assessed using the acute radiation morbidity scoring criteria and late radiation morbidity scoring scheme from the Radiation Therapy Oncology Group and the European Organisation for Research and Treatment of Cancer. The mean volume of ipsilateral breast was 731 cm³ (standard deviation ± 450; range, 151-2205) and the mean planning target volume (PTV) was 139 cm³ (standard deviation ± 48; range, 55-259). There was good correlation between ipsilateral breast V_15Gy and the ratio between the PTV and ipsilateral breast volume (R² = .911). At a median follow-up of 4.5 years, 32% of patients (n = 16) developed any grade 1 acute toxic effect. No grade >1 toxic effect was observed. Sixteen percent of patients (n = 8) developed any grade 1 late toxic effect. No grade >1 toxic effect was observed. Physician-assessed cosmesis was reported as excellent (84%), good (14%), and fair (2%). The schedule of 30 Gy in 5 consecutive fractions might represent a safe, easy-to-deliver, and cost-effective option for appropriately selected patients affected by early breast cancer.

End-to-end test for lung SBRT: An Italian multicentric pilot experience

PURPOSE

Set up a lung SBRT end-to-end (e2e) test and perform a multicentre validation.

MATERIAL AND METHODS

A group of medical physicists from four hospitals and the Italian Institute of Ionizing Radiation Metrology designed the present e2e test. One sub-group set up the test, while another tested its feasibility and ease of use. A satisfaction questionnaire was used to collect user feedback. Each participating centre (PC) received the ADAM breathing phantom, a microDiamond detector and radiochromic films. Following the e2e protocol, each PC performed its standard internal procedure for simulating, planning, and irradiating the phantom. Each PC uploaded its planning and treatment delivery data in a shared Google Drive. A single centre analyzed all the data.

RESULTS

The e2e test was successfully performed by all PCs. Participants' comments indicated that ADAM was well suited to the purpose and the protocol well described. All PCs performed the test in static and dynamic modes. The ratio between measured and planned point dose obtained by PC1, PC2, PC3, PC4 was: 0.99, 0.96, 1.01 and 1.01 (static track) and 0.99, 1.02, 1.01 and 0.94 (dynamic track). The gamma passing rates (3 % global, 3 mm) between planned and measured dose maps were 98.5 %, 94.0 %, 99.1 % and 94.0 % (static track) and 99.5 %, 96.5 %, 86.0 % and 94.5 % (dynamic track) for PC1, PC2, PC3 and PC4, respectively.

CONCLUSIONS

An e2e test for lung SBRT has been proposed and tested in a multicentre framework. The results and user feedback prove the validity of the proposed e2e test.

Radiotherapy for elderly patients with glioblastoma: an assessment of hypofractionation and modern treatment techniques

Glioblastoma (GBM) is a disease with a poor prognosis. For decades, radiotherapy has played a critical role in the management of GBM. The standard of care radiation prescription is 60 Gy in 30 fractions, but landmark trials have historically excluded patients older than 70 years. Currently, there is considerable variation in the management of elderly patients with GBM. Shortened radiation treatment (hypofractionated) regimens have been explored since conventional treatment schedules are lengthy and many elderly patients have functional, cognitive, and social limitations. Clinical trials have demonstrated the effectiveness of hypofractionated radiotherapy (40 Gy in 15 fractions) to treat elderly or frail patients with GBM. Although previous studies have suggested these unique hypofractionation prescriptions effectively treat these patients, there are many avenues for improvement in this patient population. Herein, we describe the unique tumor biology of glioblastoma, key hypofractionated radiotherapy studies, and health-related quality of life (HRQOL) studies for elderly patients with GBM. Hypofractionated radiation has emerged as a shortened alternative and retrospective studies have suggested survival outcomes are similar for elderly patients with GBM. Prospective studies comparing hypofractionation with conventional treatment regiments are warranted. In addition to evaluating survival outcomes, HRQOL endpoints should be incorporated into future studies.

Accelerated hypofractionated radiation for elderly or frail patients with a newly diagnosed glioblastoma: A pooled analysis of patient-level data from 4 prospective trials

BACKGROUND

The standard of care for elderly or frail patients with glioblastoma (GBM) is 40 Gy in 15 fractions of radiotherapy. However, this regimen has a lower biological effective dose (BED) compared with the Stupp regimen of 60 Gy in 30 fractions. It is hypothesized that accelerated hypofractionated radiation of 52.5 Gy in 15 fractions (BED equivalent to Stupp) is safe and efficacious.

METHODS

Elderly or frail patients with GBM treated with 52.5 Gy in 15 fractions were pooled from 3 phase 1/2 studies and a prospective observational study. Overall survival (OS) and progression-free survival (PFS) were defined time elapsing between surgery/biopsy and death from any cause or progression of disease.

RESULTS

Sixty-two newly diagnosed patients were eligible for this pooled analysis of individual patient data. The majority (66%) had a Karnofsky performance status (KPS) score <70. The median age was 73 years. The median OS and PFS were 10.3 and 6.9 months, respectively. Patients with KPS scores ≥70 and <70 had a median OS of 15.3 and 9.5 months, respectively. Concurrent chemotherapy was an independent prognostic factor for improved PFS and OS. Grade 3 neurologic toxicity was seen in 2 patients (3.2%). There was no grade 4/5 toxicity.

CONCLUSIONS

This is the only analysis of elderly/frail patients with GBM prospectively treated with a hypofractionated radiation regimen that is isoeffective to the Stupp regimen. Treatment was well tolerated and demonstrated excellent OS and PFS compared with historical studies. This regimen gives the elderly/frail population an alternative to regimens with a lower BED. Randomized trials are needed to validate these results.

Clinical validation of an automatic atlas‐based segmentation tool for male pelvis CT images

Purpose

This retrospective work aims to evaluate the possible impact on intra‐ and inter‐observer variability, contouring time, and contour accuracy of introducing a pelvis computed tomography (CT) auto‐segmentation tool in radiotherapy planning workflow.

Methods

Tests were carried out on five structures (bladder, rectum, pelvic lymph‐nodes, and femoral heads) of six previously treated subjects, enrolling five radiation oncologists (ROs) to manually re‐contour and edit auto‐contours generated with a male pelvis CT atlas created with the commercial software MIM MAESTRO. The ROs first delineated manual contours (M). Then they modified the auto‐contours, producing automatic‐modified (AM) contours. The procedure was repeated to evaluate intra‐observer variability, producing M1, M2, AM1, and AM2 contour sets (each comprising 5 structures × 6 test patients × 5 ROs = 150 contours), for a total of 600 contours. Potential time savings was evaluated by comparing contouring and editing times. Structure contours were compared to a reference standard by means of Dice similarity coefficient (DSC) and mean distance to agreement (MDA), to assess intra‐ and inter‐observer variability. To exclude any automation bias, ROs evaluated both M and AM sets as “clinically acceptable” or “to be corrected” in a blind test.

Results

Comparing AM to M sets, a significant reduction of both inter‐observer variability (p < 0.001) and contouring time (‐45% whole pelvis, p < 0.001) was obtained. Intra‐observer variability reduction was significant only for bladder and femoral heads (p < 0.001). The statistical test showed no significant bias.

Conclusion

Our atlas‐based workflow proved to be effective for clinical practice as it can improve contour reproducibility and generate time savings. Based on these findings, institutions are encouraged to implement their auto‐segmentation method.

European Society for Radiotherapy and Oncology Advisory Committee in Radiation Oncology Practice consensus recommendations on patient selection and dose and fractionation for external beam radiotherapy in early breast cancer

High-quality randomised clinical trials testing moderately fractionated breast radiotherapy have clearly shown that local control and survival is at least as effective as with 2 Gy daily fractions with similar or reduced normal tissue toxicity. Fewer treatment visits are welcomed by patients and their families, and reduced fractions produce substantial savings for health-care systems. Implementation of hypofractionation, however, has moved at a slow pace. The oncology community have now reached an inflection point created by new evidence from the FAST-Forward five-fraction randomised trial and catalysed by the need for the global radiation oncology community to unite during the COVID-19 pandemic and rapidly rethink hypofractionation implementation. The aim of this paper is to support equity of access for all patients to receive evidence-based breast external beam radiotherapy and to facilitate the translation of new evidence into routine daily practice. The results from this European Society for Radiotherapy and Oncology Advisory Committee in Radiation Oncology Practice consensus state that moderately hypofractionated radiotherapy can be offered to any patient for whole breast, chest wall (with or without reconstruction), and nodal volumes. Ultrafractionation (five fractions) can also be offered for non-nodal breast or chest wall (without reconstruction) radiotherapy either as standard of care or within a randomised trial or prospective cohort. The consensus is timely; not only is it a pragmatic framework for radiation oncologists, but it provides a measured proposal for the path forward to influence policy makers and empower patients to ensure equity of access to evidence-based radiotherapy.

Implementation of automatic plan optimization in Italy: Status and perspectives

PURPOSE

To investigate and report on the diffusion and clinical use of automated radiotherapy planning systems in Italy and to assess the perspectives of the community of Italian medical physicists involved in radiotherapy on the use of these tools.

MATERIALS AND METHODS

A survey of medical physicists (one per Institute) of 175 radiotherapy centers in Italy was conducted between February 21st and April 1st, 2021. The information collected included the institute's characteristics, plan activity, availability/use of automatic tools and related issues regarding satisfaction, criticisms, expectations, and perceived professional modifications. Responses were analysed, including the impact of a few variables such as the institute type and experience.

RESULTS

125 of the centers (71%) answered the survey, with regional variability (range: 47%-100%); among these, 49% have a TPS with some automatic option. Clinical use of automatic planning is present in 33% of the centers, with 13% applying it in >50% of their plans. Among the 125 responding centres the most used systems are Pinnacle (16%), Raystation (9%) and Eclipse (4%). The majority of participants consider the use of automated techniques to be beneficial, while only 1% do not see any advantage; 83% of respondents see the possibility of enriching their professional role as a potential benefit, while 3% see potential threats.

CONCLUSIONS

Our survey shows that 49% of the responding centres have an automatic planning solution although clinically used in only 33% of the cases. Most physicists consider the use of automated techniques to be beneficial and show a prevalently positive attitude.

CTNI-37. ISOEFFECTIVE HYPOFRACTIONATION FOR ELDERLY OR FRAIL PATIENTS WITH A NEWLY DIAGNOSED GLIOBLASTOMA: A POOLED INTERNATIONAL STUDY

PURPOSE

The standard of care (SOC) for elderly or frail glioblastoma (GBM) patients is 40 Gy in 15 fraction radiotherapy. However, this regimen has a lower BED compared to the Stupp regimen, 60 Gy in 30 fractions. We hypothesize that isoeffective hypofractionated radiation of 52.5 Gy in 15 fractions (BED equivalent to Stupp) will have superior survival compared to standard of care.

METHODS

Elderly GBM patients treated with 52.5 Gy in 15 fractions were pooled from 2 phase II studies, 1 phase 1 and a prospective observation study. Overall survival (OS) and progression free survival (PFS) were defined as the time elapsed between surgery/biopsy and death from any cause or progression. Univariate and multivariate analyses were performed.

RESULTS

62 newly-diagnosed patients were eligible for this analysis. Median follow-up was 10 months. The median OS and PFS was 10.3 and 6.9 mos, respectively. Patients with KPS ≥ 70 and &lt; 70 had a median OS of 15.3 and 9.5 mos. No survival difference was seen between unmethylated and methylated patients with a median OS of 10.2 and 10.3 months, respectively. Multivariable analysis demonstrated that concurrent chemotherapy was an independent prognostic factor for improved PFS and OS. Grade 3 neurologic toxicity was seen in 2 patients (3.2%).

CONCLUSION

This is the first pooled, prospective analysis of elderly/frail GBM patients treated with dose-escalated hypofractionated radiation. Treatment was well tolerated and demonstrated excellent OS and PFS, exceeding that from prior elderly trials (Roa; 6.5 mo [poor KPS]/Perry; 9.3mo [good KPS]). This treatment regimen gives the elderly population an alternative to Stupp that is not de-escalating therapy. Future prospective trials are needed to validate these results.

A Delphi study and International Consensus Recommendations: The use of bolus in the setting of postmastectomy radiation therapy for early breast cancer

Bolus serves as a tissue equivalent material that shifts the 95-100% isodose line towards the skin and subcutaneous tissue. The need for bolus for all breast cancer patients planned for postmastectomy radiation therapy (PMRT) has been questioned. The work was initiated by the faculty of the European SocieTy for Radiotherapy & Oncology (ESTRO) breast cancer courses and represents a multidisciplinary international breast cancer expert collaboration to optimize PMRT. Due to the lack of randomised trials evaluating the benefits of bolus, we designed a stepwise project to evaluate the existing evidence about the use of bolus in the setting of PMRT to achieve an international consensus for the indications of bolus in PMRT, based on the Delphi method.

The use of bolus in postmastectomy radiation therapy for breast cancer: A systematic review

PURPOSE

Post mastectomy radiation therapy (PMRT) reduces locoregional recurrence (LRR) and breast cancer mortality for selected patients. Bolus overcomes the skin-sparing effect of external-beam radiotherapy, ensuring adequate dose to superficial regions at risk of local recurrence (LR). This systematic review summarizes the current evidence regarding the impact of bolus on LR and acute toxicity in the setting of PMRT.

RESULTS

27 studies were included. The use of bolus led to higher rates of acute grade 3 radiation dermatitis (pooled rates of 9.6% with bolus vs. 1.2% without). Pooled crude LR rates from thirteen studies (n = 3756) were similar with (3.5%) and without (3.6%) bolus.

CONCLUSIONS

Bolus may be indicated in cases with a high risk of LR in the skin, but seems not to be necessary for all patients. Further work is needed to define the role of bolus in PMRT.

Association of Breast Cancer Irradiation With Cardiac Toxic Effects: A Narrative Review

IMPORTANCE

To promptly recognize and manage cardiovascular (CV) risk factors before, during, and after cancer treatment, decreasing the risk of cancer therapy-related cardiac dysfunction is crucial. After recent advances in breast cancer treatment, mortality rates from cancer have decreased, and the prevalence of survivors with a potentially higher CV disease risk has increased. Cardiovascular risks might be associated with the multimodal approach, including systemic therapies and breast radiotherapy (RT).

OBSERVATIONS

The heart disease risk seems to be higher in patients with tumors in the left breast, when other classic CV risk factors are present, and when adjunctive anthracycline-based chemotherapy is administered, suggesting a synergistic association. Respiratory control as well as modern RT techniques and their possible further refinement may decrease the prevalence and severity of radiation-induced heart disease. Several pharmacological cardioprevention strategies for decreasing cardiac toxic effects have been identified in several guidelines. However, further research is needed to ascertain the feasibility of these strategies in routine practice.

CONCLUSIONS AND RELEVANCE

This review found that evidence-based recommendations are lacking on the modalities for and intensity of heart disease screening, surveillance of patients after RT, and treatment of these patients. A multidisciplinary and multimodal approach is crucial to guide optimal management.

In phantom evaluation of targeting accuracy in MRI-based brain radiosurgery

PURPOSE

To determine the targeting accuracy of brain radiosurgery when planning procedures employing different MRI and MRI + CT combinations are adopted.

MATERIALS AND METHOD

A new phantom, the BrainTool, has been designed and realized to test image co-registration and targeting accuracy in a realistic anatomical situation. The phantom was created with a 3D printer and materials that mimic realistic brain MRI and CT contrast using a model extracted from a synthetic MRI study of a human brain. Eight markers distributed within the BrainTool provide for assessment of the accuracy of image registrations while two cavities that host an ionization chamber are used to perform targeting accuracy measurements with an iterative cross-scan method. Two procedures employing 1.5 T MRI-only or a combination of MRI (taken with 1.5 T or 3 T scanners) and CT to carry out Gamma Knife treatments were investigated. As distortions can impact targeting accuracy, MR images were preliminary evaluated to assess image deformation extent using GammaTool phantom.

RESULTS

MR images taken with both scanners showed average and maximum distortion of 0.3 mm and 1 mm respectively. The marker distances in co-registered images resulted below 0.5 mm for both MRI scans. The targeting mismatches obtained were 0.8 mm, 1.0 mm and 1.2 mm for MRI-only and MRI + CT (1,5T and 3 T), respectively.

CONCLUSIONS

Procedures using a combination of MR and CT images provide targeting accuracies comparable to those of MRI-only procedures. The BrainTool proved to be a suitable tool for carrying out co-registration and targeting accuracy of Gamma Knife brain radiosurgery treatments.

Validation of a secondary dose check tool against Monte Carlo and analytical clinical dose calculation algorithms in VMAT

PURPOSE

Patient-specific quality assurance (QA) is very important in radiotherapy, especially for patients with highly conformed treatment plans like VMAT plans. Traditional QA protocols for these plans are time-consuming reducing considerably the time available for patient treatments. In this work, a new MC-based secondary dose check software (SciMoCa) is evaluated and benchmarked against well-established TPS (Monaco and Pinnacle3 ) by means of treatment plans and dose measurements.

METHODS

Fifty VMAT plans have been computed using same calculation parameters with SciMoCa and the two primary TPSs. Plans were validated with measurements performed with a 3D diode detector (ArcCHECK) by translating patient plans to phantom geometry. Calculation accuracy was assessed by measuring point dose differences and gamma passing rates (GPR) from a 3D gamma analysis with 3%-2 mm criteria. Comparison between SciMoCa and primary TPS calculations was made using the same estimators and using both patient and phantom geometry plans.

RESULTS

TPS and SciMoCa calculations were found to be in very good agreement with validation measurements with average point dose differences of 0.7 ± 1.7% and -0.2 ± 1.6% for SciMoCa and two TPSs, respectively. Comparison between SciMoCa calculations and the two primary TPS plans did not show any statistically significant difference with average point dose differences compatible with zero within error for both patient and phantom geometry plans and GPR (98.0 ± 3.0% and 99.0 ± 3.0% respectively) well in excess of the typical 95 % clinical tolerance threshold.

CONCLUSION

This work presents results obtained with a significantly larger sample than other similar analyses and, to the authors' knowledge, compares SciMoCa with a MC-based TPS for the first time. Results show that a MC-based secondary patient-specific QA is a clinically viable, reliable, and promising technique, that potentially allows significant time saving that can be used for patient treatment and a per-plan basis QA that effectively complements traditional commissioning and calibration protocols.

Selection criteria for early breast cancer patients in the DBCG proton trial - The randomised phase III trial strategy

BACKGROUND AND PURPOSE

Adjuvant radiotherapy of internal mammary nodes (IMN) improves survival in high-risk early breast cancer patients but inevitably leads to more dose to heart and lung. Target coverage is often compromised to meet heart/lung dose constraints. We estimate heart and lung dose when target coverage is not compromised in consecutive patients. These estimates are used to guide the choice of selection criteria for the randomised Danish Breast Cancer Group (DBCG) Proton Trial.

MATERIALS AND METHODS

179 breast cancer patients already treated with loco-regional IMN radiotherapy from 18 European departments were included. If the clinically delivered treatment plan did not comply with defined target coverage requirements, the plan was modified retrospectively until sufficient coverage was reached. The choice of selection criteria was based on the estimated number of eligible patients for different heart and lung dose thresholds in combination with proton therapy capacity limitations and dose-response relationships for heart and lung.

RESULTS

Median mean heart dose was 3.0 Gy (range, 1.1-8.2 Gy) for left-sided and 1.4 Gy (0.4-11.5 Gy) for right-sided treatment plans. Median V17Gy/V20Gy (hypofractionated/normofractionated plans) for ipsilateral lung was 31% (9-57%). The DBCG Radiotherapy Committee chose mean heart dose ≥ 4 Gy and/or lung V17Gy/V20Gy ≥ 37% as thresholds for inclusion in the randomised trial. Using these thresholds, we estimate that 22% of patients requiring loco-regional IMN radiotherapy will be eligible for the trial.

CONCLUSION

The patient selection criteria for the DBCG Proton Trial are mean heart dose ≥ 4 Gy and/or lung V17Gy/V20Gy ≥ 37%.

Accelerated Partial-Breast Irradiation Compared With Whole-Breast Irradiation for Early Breast Cancer: Long-Term Results of the Randomized Phase III APBI-IMRT-Florence Trial

PURPOSE

To report the long-term results of external-beam accelerated partial-breast irradiation (APBI) intensity-modulated radiation therapy (IMRT) Florence phase III trial comparing whole-breast irradiation (WBI) to APBI in early-stage breast cancer.

PATIENTS AND METHODS

The primary end point was to determine the 5-year difference in ipsilateral breast tumor recurrence (IBTR) between 30 Gy in 5 once-daily fractions (APBI arm) and 50 Gy in 25 fractions with a tumor bed boost (WBI arm) after breast-conserving surgery.

RESULTS

Five hundred twenty patients, more than 90% of whom had characteristics associated with low recurrence risk, were randomly assigned (WBI, n = 260; APBI, n = 260) between 2005 and 2013. Median follow-up was 10.7 years. The 10-year cumulative incidence of IBTR was 2.5% (n = 6) in the WBI and 3.7% (n = 9) in the APBI arm (hazard ratio [HR], 1.56; 95% CI, 0.55 to 4.37; P = .40). Overall survival at 10 years was 91.9% in both arms (HR, 0.95; 95% CI, 0.50 to 1.79; P = .86). Breast cancer–specific survival at 10 years was 96.7% in the WBI and 97.8% in the APBI arm (HR, 0.65; 95% CI, 0.21 to 1.99; P = .45). The APBI arm showed significantly less acute toxicity ( P = .0001) and late toxicity ( P = .0001) and improved cosmetic outcome as evaluated by both physician ( P = .0001) and patient ( P = .0001).

CONCLUSION

The 10-year cumulative IBTR incidence in early breast cancer treated with external APBI using IMRT technique in 5 once-daily fractions is low and not different from that after WBI. Acute and late treatment-related toxicity and cosmesis outcomes were significantly in favor of APBI.

Methodological approach to create an atlas using a commercial auto-contouring software

PURPOSE

The aim of this work was to establish a methodological approach for creation and optimization of an atlas for auto-contouring, using the commercial software MIM MAESTRO (MIM Software Inc. Cleveland OH).

METHODS

A computed tomography (CT) male pelvis atlas was created and optimized to evaluate how different tools and options impact on the accuracy of automatic segmentation. Pelvic lymph nodes (PLN), rectum, bladder, and femurs of 55 subjects were reviewed for consistency by a senior consultant radiation oncologist with 15 yr of experience. Several atlas and workflow options were tuned to optimize the accuracy of auto-contours. The deformable image registration (DIR), the finalization method, the k number of atlas best matching subjects, and several post-processing options were studied. To test our atlas performances, automatic and reference manual contours of 20 test subjects were statistically compared based on dice similarity coefficient (DSC) and mean distance to agreement (MDA) indices. The effect of field of view (FOV) reduction on auto-contouring time was also investigated.

RESULTS

With the optimized atlas and workflow, DSC and MDA median values of bladder, rectum, PLN, and femurs were 0.91 and 1.6 mm, 0.85 and 1.6 mm, 0.85 and 1.8 mm, and 0.96 and 0.5 mm, respectively. Auto-contouring time was more than halved by strictly cropping the FOV of the subject to be contoured to the pelvic region.

CONCLUSION

A statistically significant improvement of auto-contours accuracy was obtained using our atlas and optimized workflow instead of the MIM Software pelvic atlas.

Exclusive endocrine therapy or partial breast irradiation for women aged ≥70 years with luminal A-like early stage breast cancer (NCT04134598 - EUROPA): Proof of concept of a randomized controlled trial comparing health related quality of life by patient reported outcome measures

BACKGROUND

Postoperative radiation therapy after breast conserving surgery in the older adult population is a matter of debate; although radiation therapy was shown to benefit these patients concerning local disease control, the absolute benefit was small and potentially negligible. Partial breast irradiation has been introduced as an alternative treatment approach for low-risk patients. Older adult patients with early breast cancer constitute a unique population with regards to prognosis and potential comorbidities, thus minimizing treatment to maintain health-related quality of life (HRQoL) without compromising survival is extremely important. Estimates of the patient's risk of benefit and/or harm with treatment should be performed together with an assessment of baseline comorbidities, life expectancy, and care preferences. Published data suggest that radiation therapy or endocrine therapy alone resulted in excellent disease control in older women with early breast cancer, and that the combination of both treatments has less incremental benefit than expected. Conversely, the toxicity profile of endocrine therapy is well known, often significantly impacting long term HRQoL of these potentially frail patients.

METHODS

Patients older than 70  years receiving breast conserving surgery with T1N0, Luminal A-like tumors will be randomized to receive partial breast irradiation-alone or endocrine therapy-alone. The main objectives are to determine patient reported outcome measures in terms of HRQoL, as assessed by the EORTC QLQ-C30 using the global health status of patients, and to demonstrate a non-inferior local control rate between arms. Secondary endpoints are represented by individual scales from QLQ-C30 and module QLQ-BR45 scores; ELD14 questionnaire; geriatric COre DatasEt assessment; distant control rate, adverse events rates, breast cancer specific, and overall survival.

DISCUSSION

The EUROPA trial is a new randomized trial focused on older adults (≥70  years) affected by good prognosis primary breast cancer. Our assumption is that postoperative radiation therapy-alone avoids the long-term toxicity of endocrine therapy and favorably impacts on HRQoL in this population. In the current report we present the trial's background and methods, focusing on perspectives in the field of precision medicine.

TRIAL REGISTRATION

The trial is registered with ClinicalTrial.gov Identifier NCT04134598 / EUROPA trial.

The impact of age on early breast cancer after breast conserving therapy: Results of a subanalysis from the accelerated partial breast irradiation IMRT Florence trial

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Background: The impact of age on local recurrence rate of patients affected by early breast cancer is still unclear. The standard of care for older adult largely varies depending on patient- and tumor-related features, but also on national guidelines. We recently presented the 10 years median follow update of the APBI-IMRT Florence phase III trial. The primary aim of the present analysis is to identify the potential relationship between age and ipsilateral breast tumor recurrence (IBTR) in this setting of patients. Methods: This retrospective analysis was performed on the whole series of 520 patients who were enrolled in the trial after breast conserving surgery and randomized to receive APBI or whole breast irradiation. We analyzed patients stratified by age (70+ vs 40-69 years). Results: At a median follow up time of 10.7 years, we recorded 15 IBTR events. Four hundred and three patients (77.5%) were aged less than 70 years old (11 IBTR) and 117 patients (22.5%) were aged 70 years or older (4 IBTR). At the univariate analysis the age (70+ vs 40-69 years) was not significantly correlated with IBTR occurrence (HR 1.33, 95% CI 0.42-4.17; p=0.63). The only significant prognostic factor was adjuvant endocrine therapy, also at the multivariable analysis (HR 0.26, 95% CI 0.07-0.94; p=0.041). Main results are summarized in the table. Within the luminal-like patients (n=437; 12 IBTR events), the age did not impact on the IBTR rate (HR 0.91, 95% CI 0.19-4.31; p=0.91) and adjuvant endocrine therapy lost its significance (HR 0.32, 95% CI 0.09-1.11; p=0.072). Conclusions: Our trial subanalysis did not demonstrate a significant effect of age on IBTR rate for early breast cancer patients receiving a breast conserving therapy. Due to the low number of events, the benefit of adjuvant endocrine therapy is unclear and calls for further investigations. Clinical trial information: NCT02104895 . [Table: see text]

Automated planning through robust templates and multicriterial optimization for lung VMAT SBRT of lung lesions

Purpose

To develop and validate a robust template for VMAT SBRT of lung lesions, using the multicriterial optimization (MCO) of a commercial treatment planning system.

Methods

The template was established and refined on 10 lung SBRT patients planned for 55 Gy/5 fr. To improve gradient and conformity a ring structure around the planning target volume (PTV) was set in the list of objectives. Ideal fluence optimization was conducted giving priority to organs at risk (OARs) and using the MCO, which further pushes OARs doses. Segmentation was conducted giving priority to PTV coverage. Two different templates were produced with different degrees of modulation, by setting the Fluence Smoothing parameter to Medium (MFS) and High (HFS).

Each template was applied on 20 further patients. Automatic and manual plans were compared in terms of dosimetric parameters, delivery time, and complexity. Statistical significance of differences was evaluated using paired two‐sided Wilcoxon signed‐rank test.

Results

No statistically significant differences in PTV coverage and maximum dose were observed, while an improvement was observed in gradient and conformity. A general improvement in dose to OARs was seen, which resulted to be significant for chest wall V_30 Gy, total lung V_20 Gy, and spinal cord D_0.1 cc. MFS plans are characterized by a higher modulation and longer delivery time than manual plans. HFS plans have a modulation and a delivery time comparable to manual plans, but still present an advantage in terms of gradient.

Conclusion

The automation of the planning process for lung SBRT using robust templates and MCO was demonstrated to be feasible and more efficient.

Dosimetric Predictors of Acute and Chronic Alopecia in Primary Brain Cancer Patients Treated With Volumetric Modulated Arc Therapy

Purpose: To determine dose constraints that correlate with alopecia in patients treated with photon-based Volumetric Modulated Arc Therapy (VMAT) for primary brain tumors.

Methods: During the treatment planning process, the scalp was drawn as a region of interest. Dose received by 0.1 cc (D_0.1cc), mean dose (D_mean), absolute volumes receiving different doses (V_16Gy, V_20Gy, V_25Gy, V_30Gy, V_35Gy, V_40Gy, and V_43Gy) were registered for the scalp. Alopecia was assessed according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Receiver operating characteristics (ROC) curve analysis was used to identify parameters associated with hair-loss.

Results: One-hundred and one patients were included in this observational study. At the end of radiotherapy (RT), 5 patients did not develop alopecia (D_mean scalp 3.1 Gy). The scalp of the patients with G1 (n = 11) and G2 (n = 85) alopecia received D_mean of 10.6 Gy and 11.8 Gy, respectively. At ROC analysis, V_16Gy20Gy ≥ 5.2 cc were the strongest predictors of acute alopecia risk. Chronic hair-loss assessment was available for 74 patients: median time to recovery from G2 alopecia was 5, 9 months. The actuarial rate of hair regrowth was 98.1% at 18 months after the end of RT. At ROC analysis, V_40Gy43Gy ≥2.2 cc were the strongest predictors of chronic G2-alopecia risk. V_20Gy, V_40Gy, and D_0,1cc were shown to be independent variables according to correlation coefficient r.

Conclusions: V_20Gy and V_40Gy were the strongest predictors for acute and chronic G2 hair-loss, respectively. The low-dose bath typical of VMAT corresponds to large areas of acute but transient alopecia. However, the steep dose gradient of VMAT allows to reduce the areas of the scalp that receive higher doses, minimizing the risk of permanent alopecia.

The application of our dosimetric findings for the scalp may help in reducing the alopecia risk and also in estimating the probability of hair-loss during patient counseling before starting radiotherapy.

Analysis of skin dose distribution for the prediction of severe radiation dermatitis in head and neck squamous cell carcinoma patients treated with concurrent chemo-radiotherapy

BACKGROUND

We investigated whether the pattern of intensity-modulated radiotherapy (IMRT) dose distribution to the skin can be correlated with the development of G3/G4 radiation dermatitis (RD).

METHODS

A frequency-matched cohort analysis was perfomed on patients treated with IMRT and concurrent cisplatin or cetuximab. Risk ratios were obtained by fitting Poisson regression models.

RESULTS

The incidence of G3/G4 RD was 41.1% in 90 patients included (50% vs 36.6% in the cetuximab and cisplatin cohorts, respectively). In multivariate analysis, PS ≥ 1 and weight loss at RT completion >10 kg were the only factors that retained significance. The best dosimetric predictive accuracy was provided by 19.9 cc and 5.8 cc of skin ring 2 mm V50 and V60, respectively (AUC: 0.61 for both).

CONCLUSION

Along with clinical factors, the pattern of dose distribution to a ring structure localized 2 mm below the patient's surface may help predict the development of severe RD.