When a cancer disappears before surgery, does it mean patients live longer? Not always, a major review finds.

For people with stomach or esophageal cancer, a major goal of treatment before surgery is to shrink or even eliminate the tumor—what doctors call a 'pathologic complete response' or pCR. It's a hopeful sign, and for years, clinical trials have used it as a shortcut to predict whether a new treatment will help patients live longer. But a new, large review of 26 randomized trials involving over 7,400 patients suggests we should be very careful with that hope. The analysis found that, overall, whether a patient achieved a pCR had almost no meaningful connection to how long they ultimately lived. At the trial level, when a treatment improved pCR rates, that improvement explained very little about whether it also improved overall survival. The story gets more complicated when you look at specific cancers. For cancers starting in the esophagus, a complete response was a very strong predictor of longer life. For stomach cancers, the link was moderate. But for cancers at the junction of the stomach and esophagus, there was no link at all. The type of treatment also mattered: trials that included radiation showed a strong link, while chemotherapy-only trials did not. The bottom line: a tumor disappearing before surgery is a positive event, but it's not a reliable guarantee of survival for most patients with these cancers, and doctors need to interpret trial results with caution.