Treatment Efficacy Score to compare neoadjuvant chemotherapy efficacy between randomized trial arms in breast cancer

Difference in pathologic complete response (pCR) rate after neoadjuvant chemotherapy does not capture the impact of treatment on downstaging of residual cancer in the experimental arm. The I-SPY consortium developed a method to compare the entire distribution of residual cancer burden (RCB) values between breast cancer trial arms to better quantify the differences in cytotoxic efficacy of treatments. The Treatment Efficacy Score (TES) reflects the area between the weighted cumulative distribution functions of RCB values from two trial arms. TES identifies arms with higher pCR rate but was more accurate to identify regimens as less effective if treatment did not reduce the frequency of high RCB values, even if pCR rate improved. The correlation between TES and survival was higher than the correlation between pCR rate difference and survival.