Comparison of hypofractionated and conventionally fractionated whole-breast irradiation for early breast cancer patients: a single-institute study of 1,098 patients

Purpose To evaluate the efficacy and safety of hypofractionated whole-breast irradiation (HF-WBI) compared with conventionally fractionated (CF) WBI. Materials and methods Patients with early breast cancer (stages 0–II and <3 positive lymph nodes) who had undergone breast-conserving surgery were eligible for the HF-WBI study. HF-WBI was administered at 43.2 Gy in 16 fractions over 3.2 weeks to the whole breast with an additional tumor-bed boost of 8.1 Gy in 3 fractions over 3 days for positive surgical margins or those <5 mm. CF-WBI was administered at 50 Gy in 25 fractions over 5 weeks to the whole breast with an additional tumor-bed boost of 16 Gy in 8 fractions over 1.4 weeks to 6 Gy in 3 fractions over 3 days, depending on margin status. Results From April 1, 2006, to December 31, 2010, 717 patients were registered and 734 breasts were treated by HF-WBI. In the same period, 381 patients and 393 breasts who matched the study criteria chose CF-WBI, so the total number of patients in this comparison was 1,098. Grade 2 acute skin reactions were observed for 24 patients (3 %) in the HF-WBI group and 53 patients (14 %) in the CF-WBI ( p < 0.001) group. The median follow-up period was 27 months. Two cases of intrabreast tumor recurrence were observed in each treatment group. Regional lymph node recurrence was observed in 1 HF-WBI patient and 2 CF-WBI patients. Conclusion HF-WBI is superior to CF-WBI in terms of acute skin reaction and has the same short-term efficacy.