Survival benefit from axillary surgery in patients aged 70 years or older with clinically node-negative breast cancer: A population-based propensity-score matched analysis

Background: Older patients with breast cancer have good prognosis and most die from diseases other than breast cancer. Previous studies suggested that the surgical extent in older patients could be reduced. We aimed to compare survival outcomes in patients aged ≥70 years with clinically node-negative breast cancer, based on whether axillary surgery was performed. Methods: A total of 2,995 patients with breast cancer aged ≥70 years who underwent breast surgery were included in the Korean Breast Cancer Registry. Patients were classified into two groups according to the performance of axillary surgery. We used propensity score matching for demographic and treatment factors to minimize selection bias. We compared the 5-year overall survival (OS) and breast cancer-specific survival (BCSS). Results: Among 708 patients after 3:1 propensity score matching, 531 underwent breast surgery with axillary surgery and 177 underwent breast surgery alone. Of all patients, 51.7% had T1 stage, and 73.2% underwent mastectomy. Approximately 31.2% of patients received chemotherapy. Among patients who did not undergo axillary surgery, the 5-year OS and BCSS rates were 85.2% and 96.7%, respectively. The hazard ratio of axillary surgery for OS was 0.943 (95% confidence interval 0.652–1.365, p = 0.757), indicating no significant difference between two groups. Conclusions: Our study demonstrates that axillary surgery in a matched cohort of older patients with breast cancer and clinically negative nodes does not provide a survival benefit compared to patients undergoing breast surgery alone. These findings suggest that axillary surgery may be safely omitted in a select group of patients aged ≥70 years with clinically node-negative cancer. Further studies are needed to identify potential candidates for omitting axillary surgery.