Effect of Interval Between Neoadjuvant Chemotherapy and Surgery on Oncological Outcomes in Poor Responders with Locally Advanced Breast Cancer.

Purpose: The interval between neoadjuvant chemotherapy (NAC) and surgery for locally advanced breast cancer (LABC) remains controversial. At the same time, the prognostic effect of delayed surgery in patients with poor responses is currently unclear. Methods: Data was collected from patients who had poor responses to NAC and underwent modified radical surgery from January 2013 to December 2018. The interval from completion of NAC to surgery was divided into two groups: a longer (greater than four weeks) or shorter (four weeks or less) interval. The associations of these interval groups with overall survival (OS) and recurrence-free survival (RFS) were evaluated by multivariable Cox models adjusting for the existing prognostic factors. Propensity score matching (PSM) was used to minimize election bias. Results: A total of 1,229 patients (mean age, 47.2 +/- 8.9 years; median follow-up duration, 32.67 [6.57-52.63] months) were included. The 5-year OS rates were 73.2% and 60.8% in the shorter (n = 171) and longer interval group (n = 1,058), respectively, while the 3-year RFS rates were 80.8% and 71.7%, respectively. In multivariate Cox analysis, the longer interval was associated with an increased risk of mortality (hazard ratio [HR], 1.43; 95% confidence interval [CI], 1.01-2.02; p = 0.046) and recurrence (HR, 1.50; 95% CI, 1.12-1.99; p = 0.006). There was an interaction between the molecular subtype and the surgery interval for OS ( P interaction = 0.014) and RFS ( P interaction = 0.027). After PSM, no significant difference in OS (p p = 0.180) and RFS (p p = 0.069) was observed between the two groups. Conclusion: Among LABC patients with a poor response, those with a longer interval between NAC and surgery had worse OS and RFS. The results indicate that these patients should receive modified radical surgery timely, which may in turn improve their prognosis.