To the Editor The meta-analysis presented by Broglio et al1 is an attempt to extend a previously reported pooled analysis by Cortazar et al.2 Cortazar et al2 estimated an individual-level association between pathologic complete response (pCR) and event-free survival (EFS), and a trial-level association between the effects of anti–human epidermal growth factor receptor 2 (HER2) therapies on pCR and EFS. Their results clearly demonstrated that there is a strong individual-level association between pCR and EFS, but virtually no association between treatment effects on these end points, which implies that no reliable prediction can be made about the effect that a new treatment will have on EFS, based on the effect of this treatment on pCR. These results applied to breast cancer in general, but doubts remained in HER2-positive disease, of which there were only few trials.
Burzykowski T, Saad ED, Buyse M. Adoption of Pathologic Complete Response as a Surrogate End Point in Neoadjuvant Trials in HER2-Positive Breast Cancer Still an Open Question. JAMA Oncol. 2017;3(3):416. doi:10.1001/jamaoncol.2016.3941