Hypofractionation—delivering higher dosages per fraction in a shorter time—is common now. Hypofractionated radiotherapy for whole breast irradiation is preferred over CF-PMRT according to multiple randomized trials showing equivalent efficacy and safety. Post-mastectomy breast cancer hypofractionation is understudied. HF-PMRT with regional nodal irradiation has equal efficacy and toxicity to traditional fractionation (CF-PMRT).
87 of 92 histopathologically confirmed locally advanced breast cancer patients who underwent modified radical mastectomy and appropriate surgical axillary staging, WHO performance status 0-2, were eligible for this prospective, non-randomized trial from 2014–2015 and 2019–2021. HF-PMRT was 43.2 Gy in 16 fractions (2.7 Gy/fraction) or CF-PMRT was 50-50.4 Gy in 1.8-2.0 Gy/fraction to the chest wall and regional nodes with scar boost for high-risk patients. Locoregional recurrence-free survival. Overall survival, distant metastases control, disease-free survival, acute and late toxicity were secondary objectives.
Stage II and menopausal cases dominated HF-PMRT. Same age, co-morbidities, symptoms, and performance. HF-PMRT had 23.5 months of median follow-up and CF-PMRT 23. (10-39). HF-PMRT had 68% interruption days versus 8 for CF-PMRT (p<0.003). HF-PMRT had 86.3% two-year survival, CF-PMRT 100%, p = 0.126. The longer-follow-up 2014-2015 cohort showed three HF-PMRT deaths (13.6%) and no CF-PMRT deaths (1 patient died of brain metastasis after 26.9 months, another died of unknown cause after 47.5 months, and 1 died due to cardiopulmonary arrest after 17.9 months follow-up). HF-PMRT showed 68.18% disease-free survival, CF-PMRT 73.33%. No locoregional recurrence was reported. HF-PMRT showed 86.96% grade 1 acute cutaneous toxicity, CF-PMRT 53.6%. Six (8.70%) HF-PMRT and 14 (34.15%) CF-PMRT patients exhibited Grade 2 skin toxicity. Five (12.20%) CF-PMRT patients exhibited Grade 3 acute cutaneous toxicity, compared to none in HF-PMRT, p = 0.001.
This interim analysis suggests HF-PMRT is a promising therapeutic option. This observational study follows all patients for five years.
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