Postmastectomy radiotherapy in patients with T_1-2N₁ breast cancer: a single center experience and a meta-analysis

Postmastectomy radiotherapy (PMRT) in patients with T_1-2N₁ breast cancer is still controversial. This study was to evaluate the survival prognosis of T_1-2N₁ patients with or without PMRT.

From January 2006 to May 2017, 2606 female breast cancer patients underwent mastectomy in our medical center, among whom 402 patients of T_1-2N₁ stage with or without PMRT were finally analyzed. The median follow-up duration was 59.5 months. The primary endpoint was overall survival (OS). The secondary endpoint was disease-free survival (DFS).

In the study of our center, no statistically significant difference was observed between the T_1-2N₁ PMRT and non-PMRT subgroups for the 5-year OS (94.4% vs 95.4%, p = 0.667) and DFS (90.1% vs. 91.1%, p = 0.798). By the date of the last follow-up, 8.96% (n = 36) of the patients experienced any recurrence. Univariate analysis revealed that PMRT was not a prognostic factor for either OS (p = 0.667) or DFS (p = 0.798) in T_1-2N₁ patients. We then did a meta-analysis on the current treatment patterns, in which 2606 PMRT and 4281 non-PMRT T_1-2N₁ breast cancer patients with mastectomy were included. The meta-analysis showed that PMRT didn't improve the OS of the patients (HR = 0.85, p = 0.11), but patients with PMRT had better DFS than those in the non-PMRT group (HR = 0.62, p < 0.001).

PMRT did not affect the survival of T_1-2N₁ breast cancer patients who underwent mastectomy, suggesting that radiotherapy may be safely omitted for them.