Clinical study of fractionated whole-breast radiotherapy followed by fractionated tumor bed boost after breast-conserving surgery

Objective To explore the safety and short-term effectiveness of hypofractionated whole-breast radiotherapy followed by fractionated tumor bed boost and conventional radiotherapy after breast-conserving surgery.Methods A total of 96 patients who underwent breast-conserving surgery in the Affiliated Hospital of Xuzhou Medical University from March 2020 to October 2022 were enrolled. According to fractionation schemes, they were divided into two groups:a conventional radiation therapy (CRT) group (whole-breast 50Gy/25f + tumor bed boost 10Gy/5f) and a hypofractionated radiotherapy (HOFRT) group (whole-breast 42.56Gy/16f+ tumor bed boost 12.5Gy/5f) group. Both groups were compared for breast-related adverse reactions, other radiotherapy adverse reactions, 1-year local control rate and distant metastasis rate.Results ①There were 42 cases (84.0%) of grades 0-1 acute dermatitis in the CRT group and 41 cases (89.1%) in the HOFRT group, as well as 8 cases (16.0%) of grades 2-3 acute dermatitis in the CRT group and 5 cases (10.9%) in the HOFRT group, without statistical differences (P=0.463). There were 4 cases of breast edema and pain in the CRT group and 2 cases in the HOFRT group, without statistical differences (P=0.752). ②For breast-related late adverse reactions, there were 2 cases (4.0%) of grade 1 subcutaneous tissue fibrosis in the CRT group and 2 cases (4.3%) in the HOFRT group, without statistical difference (P=1.000). The 6-month and 1-year good cosmetic outcome rates were 96.0% and 94.0% for the CRT group, and 95.7% and 93.4% for the HOFRT group, without statistical differences. ③There were 2 cases of asymptomatic pneumonia in each group within three months, but no grade 2 or above radiation pneumonia and radiation heart injury occurred in both groups within six months. ④The whole course of radiotherapy was about 29 days in the HOFRT group, which was significantly shorter than 40 days in the CRT group. ⑤No recurrence occurred in the irradiation field in each group within the follow-up visit period. There were 2 cases of distant metastasis, including 1 case of bone metastasis in the CRT group and 1 case of lung metastasis in the HOFRT group.Conclusions Fractionated whole-breast radiotherapy followed by fractionated tumor bed boost after breast-conserving surgery has similar adverse reaction and short-term effectiveness with conventional fractionated radiotherapy, and obviously shortens the duration of treatment. It is a safe, effective and short-duration treatment scheme, and worthy of clinical application.