For decades, oncologists have looked to the disappearance of cancer cells after chemotherapy as a hopeful sign — a kind of biological promise that the worst has passed. A new multicenter study of nearly 400 women with hormone-receptor-positive breast cancer now complicates that promise, finding that while pathological complete response reliably predicts freedom from recurrence, it does not independently foretell longer life. The study invites medicine to reckon with the difference between a tumor's short-term silence and a patient's long-term survival, and to seek more nuanced guides in the mo