HYPOFRACTIONATED RADIOTHERAPY IN BREAST CANCER: A 10-YEAR UNINSTITUTIONAL EXPERIENCE

Background: Hypofractionated radiotherapy (HYPO-RT) for breast cancer is a strategy that has been shown to be safe and effective in large international studies. However, this experience should be validated in countries with different cultures and resources availability. Objectives: To evaluate overall and disease-free survival, local control, and acute and late toxicities of patients treated with HYPO-RT. Patients and Methods: Retrospective study of breast cancer patients submitted to adjuvant HYPO-RT, with or without boost. Demographic data, disease and treatment characteristics were collected. Primary outcomes were analyzed from the date of diagnosis. Acute toxicities were considered during and up to 3 months after the end of radiotherapy, and late toxicities, after 3 months. The most severe toxicity presented was reported. Results: From March 2009 to December 2016, 392 patients (397 breasts) were treated. With a mean age of 64.2 years, 78.1% had diagnosis of invasive carcinoma and 4.8% of carcinoma in situ. Breast conserving surgery was performed in 94.5% and immediate reconstruction after mastectomy in 4 (1%) patients. Most had stage T1 (62.5%), N0 or N1mi (82.9%), luminal A or B like (81.9%) pattern. Chemotherapy was performed in 42.1%. HYPO-RT was performed in 15 or 16 daily fractions of 267 cGy and 265 cGy, respectively, with boost indicated in 23.9% of the patients. The median follow-up was 65 months (4 to 129 months). There were 21 deaths (5.3%) in the period. The overall survival at 5 and 10 years was, respectively, 95.8% and 87.7%. Local control 99.1% and 94.2% and disease-free survival 98.0% and 92.7% at 5 and 10 years, respectively. Acute radiodermatitis grade 3 or 4 was observed in 0.9% (3 patients) and chronic toxicities, fibrosis 2.8%, pain 1.5%, and grade 1 or 2 hyperchromia in 2.3%. Conclusion. HYPO-RT has been shown to be a safe and effective radiotherapy regimen with excellent disease control and overall survival rates, with low toxicity. Today it is the standard treatment schedule for breast cancer in the institution in the adjuvant setting.