Effect of different axillary management strategies on survival in elderly patients (≥70 Years) with early-stage breast cancer and 1–2 positive lymph nodes, stratified by risk factors

Objective Elderly patients (≥70 years) with early-stage breast cancer and 1–2 positive nodes exhibit markedly heterogeneous responses to different axillary management strategies, necessitating individualized treatment approaches. Specifically, SLNB combined with radiotherapy should be prioritized for patients in the high- and intermediate-risk groups, whereas SLNB alone may be sufficient for those in the low-risk group to minimize postoperative morbidity. Methods The median follow-up time was 45 months. Following PSM, the SLNB plus radiotherapy (RT) regimen conferred significantly superior OS and BCSS compared to other axillary treatment modalities in the overall cohort. Multivariate analysis identified the following as independent prognostic risk factors for BCSS: age > 76 years (HR = 2.047, 95% CI: 1.603–2.614, P < 0.001), grade II–III disease (HR = 2.060, 95% CI: 1.452–2.923, P < 0.001), having 2 positive axillary nodes (HR = 1.335, 95% CI: 1.079–1.651, P = 0.008), tumor size 1.4–5 cm (HR = 1.667, 95% CI: 1.337–2.079, P < 0.001), triple-negative subtype (HR = 2.289, 95% CI: 1.534–3.416, P < 0.001), SLNB without RT (HR = 1.873, 95% CI: 1.363–2.575, P < 0.001), and ALND without RT (HR = 1.771, 95% CI: 1.291–2.430, P < 0.001). In subgroup analyses for BCSS, the 5-year rates for the high-risk cohort were 91.3% (SLNB+RT), 76.6% (SLNB without RT), 91.5% (ALND+RT), and 84.5% (ALND without RT). For the intermediate-risk cohort, the corresponding rates were 96.9%, 92.3%, 94.9%, and 92.7%. Kaplan-Meier analyses confirmed that SLNB+RT provided significant survival benefits in both the high- and intermediate-risk groups. For the low-risk cohort, the 5-year BCSS rates were 96.3%, 95.2%, 96.5%, and 94.3%, with no statistically significant differences among the four modalities (P > 0.05). Regarding LRR, the low-risk group experienced no recurrences across all four treatment arms within 5 years. In the intermediate-risk group, the 5-year LRR rates were 6.67% (SLNB+RT), 33.33% (SLNB without RT), 7.69% (ALND+RT), and 20.00% (ALND without RT); in the high-risk group, the corresponding rates were 7.69%, 50.00%, 7.70%, and 42.86%. Results We retrospectively analyzed data from two cohorts: 8,977 patients diagnosed between 2010 and 2019 from the Surveillance, Epidemiology, and End Results (SEER) database, and 106 patients diagnosed between 2018 and 2021 at the Affiliated Hospital of Southwest Medical University. Propensity score matching (PSM) only was applied to the SEER‑database cohort (n = 8 977), yielding 5,858 matched patients divided equally into a sentinel lymph node biopsy (SLNB) group (n = 2,929) and an ALND group (n = 2,929). Clinicopathological characteristics were compared using the chi-square test and t-test. Multivariate Cox regression analysis was employed to determine prognostic factors for overall survival (OS) and BCSS, while logistic regression was used to identify risk factors for 5-year locoregional recurrence (LRR). Subgroup survival analyses stratified by different risk factors were performed using Kaplan-Meier methods, with intergroup comparisons conducted via the log-rank test. Conclusion This study aimed to identify prognostic risk factors for breast cancer-specific survival (BCSS) in elderly patients (aged ≥70 years) with early-stage breast cancer and 1–2 positive lymph nodes. Additionally, we sought to evaluate the feasibility of omitting axillary lymph node dissection (ALND) and postoperative radiotherapy in selected patients to inform clinical decision-making.