Clinical value of radiotherapy in 78 patients with pT₃N₀M₀ breast cancer after modified radical mastectomy

Objective: To investigate the value of post-mastectomy radiotherapy (PMRT) in patients with T₃N₀ breast cancer (BC) who were treated with modified radical mastectomy (MRM). Methods: A retrospective analysis was performed on the clinical data of BC patients treated with MRM from 1997 to 2014. The inclusion criteria were as follows: (1) female patients; (2) pathological diagnosis of invasive BC; (3) tumor volume greater than 5 cm without axillary lymph node metastasis; (4) the patients who received no neoadjuvant chemotherapy or endocrine therapy and had no distant metastasis or other second primary cancers. A total of 78 patients met the inclusion criteria. Forty patients (51%) received PMRT and sixty-seven patients (86%) received adjuvant chemotherapy. The Kaplan-Meier method was used to calculate overall survival (OS), disease-free survival (DFS) (DFS), and local-regional recurrence (LRR) rates, and survival differences between groups were analyzed by the log-rank test. Results: The median follow-up time was 79 months (6-232 months). For all patients,the 5-year OS, DFS, and LRR rates were 89%, 87%, and 2%, respectively. The 5-year DFS, OS and LRR rates for radiotherapy group were 84%, 84% and 0%, respectively, versus 91% (P = 0.641), 96% (P = 0.126), and 5% for non-radiotherapy group. Only estrogen receptor/progesterone receptor (ER/PR) status and molecular type had significant impacts on DFS (P = 0.002 and 0.031, respectively). One patient in non-radiotherapy group had chest wall recurrence. Conclusions: MRM is effective in reducing LRR in T₃N₀M₀ BC patients. Only ER/ PR status and molecular type significantly influence DFS. Effective systemic therapy may be helpful for some T₃N₀ patients to avoid chest wall and supraclavicular radiotherapy after MRM, but large-sample studies are needed to further confirm this conclusion. (authors)