Distant Disease‑Free Survival Is a Reliable Surrogate for Overall Survival in Most Neoadjuvant Early Breast Cancer Trials — but Not All Subtypes
A pooled individual‑patient analysis of 11 neoadjuvant RCTs (12,247 patients) finds distant disease‑free survival (DDFS) strongly predicts overall survival (OS) trial‑level effects overall (R2trial=0.91), with weakened surrogacy in hormone‑receptor‑positive subtypes.