Decreasing the Use of Sentinel Lymph Node Surgery in Women Older than 70 Years with Hormone Receptor-Positive Breast Cancer and the Impact on Adjuvant Radiation and Hormonal Therapy

Background: In 2016, SSO Choosing Wisely guidelines recommended against routine sentinel lymph node (SLN) surgery in women ≥ 70 with HR+ cN0 breast cancer. Following this, we identified a group of women at low-risk of nodal positivity where SLN may be omitted (grade 1, cT1mi-T1c, or grade 2, cT1mi-T1b). This study evaluates the impact of these changes on our practice. Methods: Retrospective chart review of women aged ≥ 70 years with HR+ cN0 breast cancer at our institution from 2010 to 2020. We compared SLN use before (2010–2016)/after (2017–2020) guideline release according to clinical risk and the association with adjuvant therapy. Results: A total of 1015 breast cancers in 987 women identified. SLN surgery rate significantly decreased from 90.6% (2010–2016) to 62.8% in 2020 (p < 0.001). This was driven by breast-conserving surgery (BCS) with SLN rates of 88.2% (2010–2016) and 46.7% in 2020. During 2017–2020, SLN use varied by risk within BCS patients: 52.2% low-risk, 81.9% higher-risk, p < 0.001. In contrast, in mastectomy patients SLN was performed in ≥ 98% regardless of risk level. SLN positivity was 13.4% overall: 7.4% in low-risk and 20.8% in higher-risk, p < 0.001. After adjusting for age and clinical risk, SLN use was not associated with adjuvant radiation [odds ratio (OR) 1.61, p = 0.11] or endocrine therapy (OR 1.12, p = 0.71). Conclusions: The Society of Surgical Oncology guideline release, followed by implementation of a clinical tool to stratify by nodal risk, was associated with decreased SLN use in women aged ≥ 70 years, in those with clinically low-risk HR+ disease surgically treated with BCS. Adjusting for confounders, omission of SLN surgery was not associated with use of subsequent adjuvant radiation or hormonal therapy.