Tailored duration of adjuvant trastuzumab for human epidermal growth factor receptor 2-positive breast cancer.

We assumed that the effect of adjuvant trastuzumab on survival is mediated by the treatment time and we conducted this trial-level meta-regression to determine the appropriate length of treatment. Twelve adjuvant trastuzumab trials (from January 2000 to June 2019, consisting of 20,271 patients) were included. We considered 12-month trastuzumab treatment as the standard. The primary study endpoint was disease-free survival (DFS). By quantifying the relationship between shortened treatment time (month) and altered recurrence risk (expressed as hazard ratio), we found the regression coefficient was 0.05 (95% confidence interval: 0.02-0.08,  = 0.002), indicating the recurrence risk would increase 5.1% for each month that treatment was shortened. Accordingly, 3, 6, and 9-month reductions in treatment time resulted in 16%, 35%, and 57% increases in recurrence risk, respectively. We revealed a significant linear association between shortened treatment time of trastuzumab and recurrence risk. The clinical duration of adjuvant trastuzumab should be tailored.