Population-based analysis of non-operative management and treatment patterns in older women with estrogen receptor-positive breast cancer.

Purpose: To examine the proportion of older women with ER + HER2- breast cancer receiving non-operative management versus surgery, and to evaluate the use of axillary staging and adjuvant radiation in this population.

Methods: We queried the SEER database to identify all women aged 70 years or older with stage I-III ER + HER2- invasive breast cancer diagnosed between 2010 and 2016. We evaluated trends in non-operative management, breast surgery, axillary staging, and adjuvant radiation according to age at diagnosis.

Results: We identified 57,351 older women with ER + HER2- disease. Overall, 3538 (6.2%) of the cohort underwent non-operative management, 38,452 (67.0%) underwent breast-conserving surgery (BCS), and 15,361 (26.8%) underwent mastectomy. The proportion of patients undergoing non-operative management increased from 2.8% among 70-74-year-old women to 30.1% in those ≥ 90 years old (p < 0.001). In 53,813 women who underwent surgery, 36,850 (68.5%) underwent sentinel lymph node biopsy, while 10,861 (20.2%) underwent axillary lymph node dissection. Subgroup analysis of 29,032 older women undergoing BCS for stage I ER + HER2- breast cancer revealed a 14.2% rate of omission of axillary staging, increasing from 5.3% in those 70-74 years to 67.6% in those ≥ 90 years old (p < 0.001). Receipt of adjuvant radiation occurred in 63.3% of older women following BCS and 18% post-mastectomy, with similar trends towards omission in older age groups.

Conclusion: Primary breast surgery remains the dominant management strategy for the majority of older women with ER + HER2- breast cancer. Omission of axillary staging and adjuvant radiation are used in a minority of eligible women undergoing breast conservation for early-stage disease.