What is the optimal time of adjuvant radiotherapy in breast cancer?

Background: Breast cancer is the most common cancer in female, Adjuvant radiotherapy is one of important part in management of non-metastatic patients, Optimum time of adjuvant radiotherapy in patients with breast cancer still unclear, the aim of our study was to evaluate the impact of time to radiotherapy (TTR) after surgery in breast cancer outcome.
Patients and Methods: Data of 304 female patients with a pathologically confirmed breast cancer (clinical stage I, II, III according to AJCC 8th 2018) who treated with definitive surgery and received adjuvant breast radiotherapy from 2005 to 2015 were retrospectively reviewed. We divided the entire group according to time to start of radiation therapy into (group A) who receive radiotherapy less than 24 weeks or (group B) more than 24 weeks and correlated to Loco regional recurrence (LRR) and Disease-free survival (DFS) overall survival (OS).
Results: Overall (304) patients were enrolled. Median DFS in group A was 5±0. 175 (95% C I 4.66 - 5.34) years, versus 3±0. 347 (CI 2.32 -3.68) years in group B (P<0.003). In terms of OS, no significant difference between the two treatment groups was found. the impact of the prognostic factors on DFS and OS in this study revealed significant impact of tumor grade, stage and her2 neu status P-value (P<0.02, P<0.01, PConclusion: adjuvant radiotherapy should be given to the patients within six months of surgery especially to those patients with high risk factors in order to increase the likelihood of achieving good local control and improve DFS.