Long-term oncologic outcomes after omitting axillary surgery in older women with early stage, node-negative breast cancer: A systematic review and meta-analysis.

Abstract

525 Background: In 2016, Choosing Wisely recommended the omission of routine sentinel lymph node biopsy (SLNB) in early stage, clinically node-negative, hormone receptor-positive, Her2-negative breast cancer in women ≥70 years old, although data supporting this was limited. Our study aimed to examine the long-term impact of omitting axillary staging in elderly women undergoing surgery for early stage, clinically node-negative breast cancer. Methods: A systematic review and meta-analysis was conducted. Medline (Ovid) and Embase were searched for published papers and abstracts using a systematic search strategy. Randomized and observational studies comparing women aged ≥70 years of age with early-stage, clinically node-negative breast cancer undergoing surgery for breast cancer with and without axillary staging, were included. Included studies reported at least one of the following outcomes: axillary recurrence (primary outcome), disease-free survival (DFS), breast cancer-specific survival (BCSS), and overall survival. Risk ratios (RR) were calculated as summary estimates for all outcomes. A weighted pooled mean difference and 95% CI was calculated using a random-effects inverse variance meta-analysis for each outcome. Heterogeneity was calculated using I2 statistics, and explored using meta-regression. The Newcastle-Ottawa Scale was used to assess the methodological quality of eligible trials, based on the selection of patients, comparability of cohorts, and the methods of outcome assessment. Results: Nine studies were eligible for meta-analysis, including data for 48,523 patients. For the primary outcome of axillary recurrence, data for 3,591 patients was meta-analyzed. Axillary staging was found to reduce the risk of axillary recurrence compared to no axillary staging, although this was not statistically significant (RR 0.59, 95% CI: 0.26 to 1.35, I2= 46.6%, p = 0.21). For overall mortality, data for 14,981 patients was meta-analyzed, and a statistically significant protective effect of axillary staging on overall mortality was demonstrated (RR 0.55, 95% CI: 0.33 to 0.90, I2= 78.1%, p= 0.003). No significant differences were observed in DFS (RR 1.02, 95% CI: 0.51 to 2.07, I2 = 0.0%, p = 0.37) and BCSS (RR 0.96, 95% CI: 0.57 to 1.62, I2 = 0.0%, p = 0.78). Conclusions: Omission of axillary surgery to stage the axilla may be associated with a higher risk of overall mortality in older women with early-stage breast cancer compared to those who undergo axillary surgery. Omission of axillary surgery in this patient population should be carefully tailored to the individual patient, taking into consideration co-morbidity, life expectancy, and formal measures of frailty. Randomized trials are required to further explore the oncologic safety of omitting axillary staging in women aged 70 years or older undergoing breast cancer surgery.