Abstract: Objective To investigate the relationship between molecular subtype and local recurrence and prognosis in patients with early-stage breast cancer and 1-3 positive axillary lymph nodes (ALNs), and to improve the individualized indications for postmastectomy radiotherapy (PMRT). Methods Clinical data of 489 patients with pT1-2N1M0 (1-3 positive ALNs) who did not receive PMRT in our hospital from 2009 to 2012 were analyzed retrospectively. The KaplanMeier method was used to calculate local recurrence rate (LRR), disease-free survival rate (DFS) and overall survival rate(OS). The Log-rank test and multivariate Cox analysis were used to determine the risk of LRR associated with different molecular types and to determine the clinicopathological factors associated with prognosis. Results In 489 breast cancer patients with pT1-2N1M0 and without PMRT, there were 229 patients with Luminal A subtype, 196 with Luminal B subtype(HER-2 negative) and 64 with triple-negative subtype, respectively. The median follow-up time was 75 months (range from 5-115 months). The molecular typing analysis showed that the 5-year LRR of the triple-negative subtype was significantly higher than that of the non-triple-negative subtype (P＜0.05), and the 5-year DFS and the 5-year OS were significantly lower than the non-triple-negative subtypes (P＜0.05). There were no significant differences in 5-year LRR, DFS, and OS between Luminal A and Luminal B (HER-2 negative) in the non-triple-negative subtypes (P＞0.05 each). Multivariate Cox regression analysis showed that age ≤ 35 years, pT2 stage and triple-negative subtypes were independent poor prognostic factors for LRR. Conclusion Molecular subtyping is helpful for the individualized evaluation of LRR in pT1-2N1M0 breast cancer patients with 1-3 positive ALNs. We recommend PMRT to improve the prognosis for patients with age ≤ 35 years, pT2 stage and triple-negative subtypes.

Key words: breast neoplasms, lymphatic metastasis, neoplasm recurrence, local, radiotherapy, prognosis, molecular subtyping