Abstract:  Background and purpose: Guidelines recommend that the axillary lymph node dissection can be omitted for T 1-2 breast cancer patients with 1-2 positive sentinel lymph nodes who undergo breast-conserving mastectomy and whole breast radiation. This study aimed to explore the independent prognostic factors for elderly breast cancer patients with 1-2 positive lymph nodes who underwent mastectomy and construct a nomogram to predict their survival following different axillary surgeries. Methods: T 1-2 invasive breast cancer patients with 1-2 positive nodes and mastectomy from 2010 to 2015 were extracted from the Surveillance, Epidemiology, and End Results (SEER) program and divided into the training cohort (n=3 647) and the validation cohort (n=1 216). Univariate and multivariate Cox analyses were used to identify independent risk factors for overall survival (OS). The nomogram was constructed to predict 3- and 5-year OS, which was validated by the concordance index (C-index) and calibration curves. Results: A total of 4 863 patients were included with a 42 months median follow-up time. The nomogram was constructed by incorporating nine independent prognostic factors (age, race, marital status, grade, subtype, T stage, axillary surgery, radiation and chemotherapy) identified by multivariate Cox analysis (P<0.05). The C-index was 0.710 (95% CI: 0.689-0.731) in the training cohort and 0.728 (95% CI: 0.691-0.765) in the validation cohort. All calibration curves showed good predictive capabilities. Conclusion: The well-validated nomogram was constructed and could be useful for individual treatment in the clinic.

Key words: Breast cancer, Positive nodes, Axillary surgery, Elderly, SEER, Prognostic nomogram