Pentoxifylline improves the oxygenation and radiation response of BA1112 rat rhabdomyosarcomas and EMT6 mouse mammary carcinomas.

Tumor hypoxia can significantly impact the efficacy of cancer therapy. Pentoxifylline, a methylxanthine derivative, can improve oxygen delivery to tissues and is widely used in the treatment of peripheral vascular disease and various cerebrovascular disorders. In this article, we show that pentoxifylline, combined with oxygen breathing, significantly improves the radiation response of two experimental tumors in vivo through improved tumor oxygenation. We also demonstrate that pentoxifylline does not directly radiosensitize EMT6 cells in vitro and does not modify the tumor radiation response when administered postirradiation to solid EMT6 tumors. Our findings confirm that preirradiation administration of pentoxifylline can improve radiation efficacy, but suggest that its role as a postirradiation modifier of treatment response, reported by others, may be tumor-specific.