Survival and Recurrence Outcomes Following Adjuvant Radiotherapy for Grade 2 Intracranial Meningiomas: 13-Year Experience in a Tertiary-Care Center.

OBJECTIVE: We sought to evaluate overall survival (OS) and local recurrence (LR) in patients with grade 2 meningiomas treated with adjuvant radiotherapy compared to surgery alone at time of diagnosis. METHODS: All patients at the authors' institution between 2007 and 2020 were retrospectively reviewed. OS, LR, and treatment toxicities were assessed. Sensitivity analyses were performed for patients with initial gross total resection (GTR) and subtotal resection (STR). Kaplan-Meier analyses and log-rank test for significance were used to compare surgery alone and adjuvant radiotherapy groups. RESULTS: We included 189 patients with mean age 57.4 ± 14.6 years. Patients were 64% female, and median follow-up was 64 (interquartile range: 20-96) months. At initial treatment, 21 patients received adjuvant radiotherapy and 168 received surgery alone. There was no significant difference for OS (hazard ratio = 1.3 [95% confidence interval 0.4-4.5], P = 0.92) overall or when limited to GTR (P = 0.38) or STR (P = 0.85). There was no significant difference in LR overall (P = 0.75) or when restricted to GTR (P = 0.77) or STR (P = 0.20). No patient had radiotherapy stopped or altered because of side effects; however, 71.4% reported tolerable side effects during the treatment period and 14.3% reported chronic side effects persisting longer than 12 months post treatment. CONCLUSIONS: In a large retrospective cohort, we found no survival or local recurrence benefit to adjuvant radiotherapy in treatment of grade 2 meningiomas. Sensitivity analysis limited to initial GTR and STR also failed to demonstrate any OS or LR benefit with adjuvant radiotherapy. In our experience, there is limited utility to upfront adjuvant radiotherapy following initial surgical resection in the treatment of grade 2 meningiomas.

Four-dimensional dose calculations for dynamic tumour tracking with a gimbal-mounted linear accelerator.

PURPOSE: In this study we present a novel method for re-calculating a treatment plan on different respiratory phases by accurately modeling the panning and tilting beam motion during DTT (the "rotation method"). This method is used to re-calculate the dose distribution of a plan on multiple breathing phases to accurately assess the dosimetry. METHODS: sIMRT plans were optimized on a breath hold computed tomography (CT) image taken at exhale (BHexhale ) for 10 previous liver stereotactic ablative radiotherapy patients. Our method was used to re-calculate the plan on the inhale (0%) and exhale (50%) phases of the four-dimensional CT (4DCT) image set. The dose distributions were deformed to the BHexhale CT and summed together with proper weighting calculated from the patient's breathing trace. Subsequently, the plan was re-calculated on all ten phases using our method and the dose distributions were deformed to the BHexhale CT and accumulated together. The maximum dose for certain organs at risk (OARs) was compared between calculating on two phases and all ten phases. RESULTS: In total, 26 OARs were examined from 10 patients. When the dose was calculated on the inhale and exhale phases six OARs exceeded their dose limit, and when all 10 phases were used five OARs exceeded their limit. CONCLUSION: Dynamic tumor tracking plans optimized for a single respiratory phase leave an OAR vulnerable to exceeding its dose constraint during other respiratory phases. The rotation method accurately models the beam's geometry. Using deformable image registration to accumulate dose from all 10 breathing phases provides the most accurate results, however it is a time consuming procedure. Accumulating the dose from two extreme breathing phases (exhale and inhale) and weighting them properly provides accurate results while requiring less time. This approach should be used to confirm the safety of a DTT treatment plan prior to delivery.

Transanal Local Excision for Patients With Rectal Cancer: Can Radiation Compensate for What Is Perceived as a Nondefinitive Surgical Approach?

BACKGROUND: Total mesorectal excision has long been the standard of care for patients with rectal cancer. However, in select patients, local excision is an appropriate alternative option. The role of adjuvant radiation therapy in patients treated with local excision is controversial and evidence is lacking. OBJECTIVE: The purpose of this study was to report oncological outcomes of patients with rectal cancer treated with local excision and adjuvant radiation. DESIGN: This study was a retrospective chart review. SETTINGS: The study was conducted at the BC Cancer Agency, a tertiary referral hospital. PATIENTS: A total of 93 patients with node-negative rectal cancer treated with local excision and adjuvant radiotherapy between 2001 and 2010 were included in the study. MAIN OUTCOME MEASURES: Patient and tumor characteristics are reported. Five-year local control, progression-free survival, and overall survival were analyzed using Kaplan-Meier methods. RESULTS: Five-year overall survival, local control, and progression-free survival for patients treated with local excision and adjuvant radiotherapy were 78.5%, 86.1%, and 83.8%. In T1 disease, local control was 92.5%. LIMITATIONS: Referral bias, selection bias, lack of uniform surveillance, and retrospective analysis are the study limitations. CONCLUSIONS: Local excision with adjuvant radiotherapy provides a good level of local control in T1 disease and remains a good treatment option for patients who are either medically not suitable for a more radical surgical approach or who refuse this procedure. Local excision and radiotherapy should not be advocated in T2/T3 disease; however, it can provide a good alternative in those patients who are not fit enough for a more radical operation.