Survival and time to initiation of adjuvant chemotherapy among breast cancer patients: a systematic review and meta-analysis

The relationship between survival and time to the start of adjuvant chemotherapy (AC) among breast cancer patients is unclear. In order to illustrate the effect of delaying the initiation of AC on survival we have undertaken a systematic review and meta-analysis. We identified 12 available studies in the meta-analysis including 15 independent analytical groups. This meta-analysis showed that a 4-week delay before AC was associated with a significantly worse overall survival (OS)(HR=1.13; 95% confidence interval [CI], 1.08–1.19) and disease free survival (DFS)(HR=1.14; 95%CI, 1.05–1.24). Two studies categorized patients into hormone receptor-positive, ERBB2-positive, and triple-negative breast cancer (TNBC) patients according to the clinicopathological features of breast cancer. The HRs for OS between waiting time (WT) ≤30 days and 31–60 days in the subgroups were extracted and analyzed. The analysis demonstrated that a WT of 31–60 days was related to worse OS among patients with TNBC (HR, 1.26; 95% CI, 1.08–1.48), but had no significant effect on OS among those with hormone receptor-positive (HR, 1.02; 95% CI, 0.89–1.15) or ERBB2-postive (HR, 0.95; 95%CI, 0.79–1.14) tumors. In this meta-analysis of the eligible literatures reviewing the time to AC, a longer waiting time to adjuvant chemotherapy may lead to worse survival in breast cancer patients, especially in TNBC patients.