Does time to adjuvant chemotherapy (TTC) affect outcomes in patients with triple-negative breast cancer?

A recent study reported that time to adjuvant chemotherapy (TTC) > 30 days was significantly associated with worse OS and DFS in triple-negative breast cancer (TNBC). Earlier studies, however, found that worse outcomes were associated with TTC > 60 days or > 90 days. As the trend for mastectomy with reconstruction continues to rise, TTC of < 30 days is often not feasible due to wound-healing issues in some of these patients. To elucidate the impact of TTC, we sought to evaluate the clinical outcomes associated with TTC in a contemporary cohort treated for TNBC at a single institution.

A single-institution database was queried to identify nonmetastatic TNBC patients who received adjuvant chemotherapy from 2009 to 2018. TTC was defined as interval between date of surgery and adjuvant chemotherapy start date. Median TTC was used to divide our cohort into four quartiles; ≤ 31, 32-42, 43-56,  and > 56 days. Logrank, Kaplan-Meier, and inverse probability weighting (IPW) tests were used to analyze disease-free (DFS) and overall survival (OS).

The mean TTC of our study cohort (n = 724) was 48 days (median TTC = 42 days). Black race, mastectomy without adjuvant radiation, and mastectomy with immediate reconstruction were associated with delayed TTC (all p-values < 0.01). In multivariate IPW analysis, TTC > 56 (n = 173) days did not impact DFS or OS compared to TTC ≤ 31 (n = 198) days (p = 0.27 and p = 0.21, respectively). Similar results were seen during subgroup analysis for groups identified as higher risk for delayed TTC.

Our results demonstrated that TTC was not significant or significantly associated with DFS or OS in patient receiving chemotherapy for operable TNBC. Our results were reassuring for patients electing mastectomy with immediate reconstruction, who may experience a longer TTC.