Sentinel lymph node biopsy in women over 70: Evaluation of rates of axillary staging and impact on adjuvant therapy in elderly women.

Background: The 2016 Society of Surgical Oncology Choosing Wisely guidelines recommended against routine sentinel lymph node biopsy in women ≥70 years old with favorable, early-stage breast cancer, as sentinel lymph node biopsy does not decrease recurrence or mortality in these patients. This study's objective was to evaluate the use of sentinel lymph node biopsy and its effect on management in elderly patients.

Methods: A retrospective analysis of female patients ≥70 years old with stage I-II, clinically node-negative, hormone-receptor positive, HER2-negative disease undergoing upfront breast cancer surgery between 2017 and 2019. Primary outcome was rate of sentinel lymph node biopsy. Secondary outcome was effect of sentinel lymph node biopsy on adjuvant therapy.

Results: In total, 142 patients were included. Median age was 76 (interquartile range 73-81), and 71.8% underwent lumpectomy. On final pathology, 57.7% had invasive ductal carcinoma, and median tumor size was 15 mm (interquartile range 10-24.3). A total of 118 patients (83.1%) underwent sentinel lymph node biopsy; of these, 27 (22.9%) were positive for N1mi (7 patients) or N1a disease (20 patients). On multivariate regression analysis, patients undergoing sentinel lymph node biopsy were more likely to be younger (odds ratio 0.87, 95% confidence interval 0.78-0.95). The major risk factor for sentinel lymph node biopsy positivity was lymphovascular invasion (odds ratio 13.4, 95% confidence interval 4.57-40.1). Patients with sentinel lymph node biopsy positivity were more likely to receive local adjuvant radiation therapy (odds ratio 4.66, 95% confidence interval 1.49-16.8) and tended to receive more adjuvant regional radiation therapy (75.0% if sentinel lymph node biopsy positive compared with 15.3% if sentinel lymph node biopsy negative, P < .001).

Conclusion: Despite the 2016 Choosing Wisely guidelines, more than 80% of patients ≥70 years old underwent sentinel lymph node biopsy at our institution. If sentinel lymph node biopsy was positive, this is associated with over 4-fold higher rates of adjuvant radiation therapy.