Risk stratification for prediction of locoregional recurrence in patients with pathologic T1-2N0 breast cancer after mastectomy.

BACKGROUND: Previous studies have revealed that nearly 15-20% of selected high-risk T1-2N0 breast cancers developed LRR after mastectomy. This study is aim to indentify the risk factors of locoregional recurrence (LRR) in patients with pathologic T1-2N0 breast cancer after mastectomy in a real-world and distinguish individuals who warrant postmastectomy radiotherapy (PMRT).

METHODS: Female patients treated from 1999 to 2014 in National Cancer Center of China were retrospectively reviewed. A competing risk model was developed to estimate the cumulative incidence of LRR with death treated as a competing event.

RESULTS: A total of 4841 patients were eligible. All underwent mastectomy plus axillary nodes dissection or sentinel node biopsy without PMRT. With a median follow-up of 56.4 months (range, 1-222 months), the 5-year LRR rate was 3.9%.Besides treatment era, age ≤ 40 years old (p < 0.001, hazard ratio [HR] = 2.262), tumor located in inner quadrant (p < 0.001, HR = 2.236), T2 stage (p = 0.020, HR = 1.419), and negative expressions of estrogen receptor (ER) and progesterone receptor (PR) (p = 0.032, HR = 1.485), were patients-related independent risk factors for LRR. The 5-year LRR rates were 1.7, 3.5, and 15.0% for patients with zero, 1-2, and 3-4 risk factors (p < 0.001).

CONCLUSIONS: Risk Stratification based on age, T stage, ER/PR status and tumor location can stratify patients with pT1-2 N0 breast cancer into subgroups with different risk of LRR. PMRT might be suggested for patients with 3-4 risk factors.