Intratumoral hypoxia, radiation resistance, and HIF-1.

Failure to achieve complete remission after radiation therapy is a predictor of patient mortality, and hypoxic cancer cells are more likely to survive radiation therapy. Recent studies have shown that radiation-induced endothelial cell death results in secondary tumor cell killing. In this issue of Cancer Cell, now provide evidence that radiation induces HIF-1-mediated expression of VEGF and bFGF in tumor cells, which promotes endothelial cell survival.