There is a paucity of literature examining the impact of timing of surgery after neoadjuvant chemotherapy.

This study aimed to analyze the impact of the time taken to initiate surgical treatment following completion of neoadjuvant chemotherapy on patients' outcomes by evaluating their pathological response, overall survival (OS), and disease-free survival (DFS).

This is a retrospective review of 611 patients diagnosed with stage II and III breast cancer that received neoadjuvant chemotherapy and surgery between January 2004 and December 2014. The data was collected from a prospectively gathered registry. The patients were stratified into three cohorts according to the time of surgery after neoadjuvant chemotherapy: <4 weeks, 4-7 weeks, or ≥8 weeks. Outcomes were assessed using Kaplan-Meier curves, and the variables were compared using log-rank statistics.

The 5-year OS rate was 89.6% and the 5-year DFS rate was 74%. OS and DFS were not significantly different when stratified according to timing of surgery; however, the trends of OS and DFS were poor when surgery was delayed for ≥8 weeks. Median OS and median DFS have not yet been reached. Of the 17% of patients that had surgery after ≥8 weeks, 12.9% had pathological complete response (pCR), while among those that received surgery 4-7 weeks and <4 weeks after neoadjuvant chemotherapy, 26% and 21% had pCR, respectively (p = 0.02). ER+/HER-2+ patients had a statistically significant decrease in pCR if surgery was performed after ≥8 weeks.

Our patients showed improved pCR if surgery was performed within 8 weeks, especially for ER+/HER-2+ patients. All patients had better OS and DFS trends if surgery was performed between 4 and 7 weeks after neoadjuvant chemotherapy.