Prognostic significance of occult lymph node metastases in breast cancer: a meta-analysis

Background: Occult metastases in axillary lymph nodes have been reported to be associated with poor prognosis in patients with breast cancer. However, studies on the prognostic value of occult metastases remain controversial. This meta-analysis aimed to evaluate the prognostic significance of occult lymph node metastases in breast cancer. Methods: : Studies published published until May, 2020, which retrospectively examined negative lymph nodes by step sectioning and/or immunohistochemistry, were retrieved from MEDLINE, EMBASE, CNKI, and Cochrane Library. The pooled Relative risk (RR) with 95% confidence interval (95% CI) for overall survival (OS) and disease-free survival (DFS) were calculated to appraise the associations between occult metastases and prognosis. Results: : The results showed patients with occult metastases in axillary lymph nodes had poorer five-year DFS (RR = 0.930; 95% CI = 0.907–0.954) and OS (RR = 0.972; 95% CI = 0.954–0.990). Furthermore, the DFS (RR = 0.887; 95% CI = 0.810–0.972) and OS (RR = 0.896; 95% CI = 0.856–0.939) of patients with occult metastases were much lower after a ten-year follow-up. Conclusions: : Occult metastases in the axillary lymph nodes of patients with breast cancer are associated with poorer disease-free and overall survival. Occult metastases might serve as a predictive factor of survival outcomes in patients with breast cancer.