Feasibility and Toxicity of Hypofractionated Radiation Therapy in Patients Undergoing Post Mastectomy Radiation Therapy.

Introduction: Post mastectomy radiation (PMRT) plays major role in breast cancer treatment. Hypofractionated radiation is a relatively newer modality. Hypofractionation is more commonly used after breast conservation surgery. Landmark trials that studied hypofractionation had fewer PMRT subjects. Here we report our study on feasibility and toxicity profile of hypofractionated PMRT. Aim: To describe the clinical and toxicity profile of patients undergoing hypofractionated 3D conformal radiation therapy in breast cancer patients. Materials & Methods: This study included patients who are eligible for post mastectomy radiation therapy above 18 years planned for adjuvant PMRT (40.05Gy in 15 fractions delivered over 3 weeks in 3D conformal radiation) to the chest wall and supraclavicular nodes between April 2021 to October 2022., active lung infection, patient preference for conventional fractionation. Dosimetric parameters to target & organs at risk were analyzed. Toxicities including hematologic, dermatitis, pharyngitis & other were monitored. Results: Of 71 patients, 70 patients were female and 1 is male. Majority (46%) of patients belonged to 46-55 years age group. Age ranged from 34 to 85 years. Mean age is 52 years. Clinical Stage IIIA was the most common stage with 29.5% patients followed by Stage IIB with 25.3% patients. Majority received adjuvant chemotherapy (52%). Mean treatment time is 21 days. All patients completed treatment without any major complications. Follow up ranged from 17 months to 27 months. Out of 71 patients, 1 patient expired on follow up after 4 months of radiation therapy due to non cancer related cause (Chronic pancreatitis). On follow up, 3 patients had distant metastasis alone (lung, bone metastasis, brain metastases) and 1 patient had both local disease and distant metastasis. 3 patients who progressed had stage IIIC disease & 1 had stage IIIB disease. The V90 to the Planned Target volume (PTV) ranged from 90.4% to 99% to right sided disease, 90.3% to 96.5% to left sided disease. Heart V17Gy ranged from 1.27% to 12.5% & heart V35Gy was 0.16% to 7.2%. Dermatitis was the most common adverse effect in this study. 31 patients (43.6%) developed fatigue during treatment. They continued their daily activities without any limitations. 35 patients (49.2%) had throat pain, of which 2 patients had it in 1st week, 21 patients had it in 2nd week and 12 patients had it in 3rd week. They were treated with non opioid analgesics. Shoulder pain was observed in 10 patients (14%) during treatment. Blood parameters were monitored weekly during treatment. No changes were observed. Conclusion: Hypofractionated post mastectomy radiation therapy is well tolerated in our study group. None of them developed any major acute reactions during and post treatment in the follow up period. Patients completed their treatment without any breaks during treatment. Respiratory motion management especially left sided disease patients should be used for achieving dose constraints. [ABSTRACT FROM AUTHOR]

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