Solid Tumor Cells Not Killed by Radiation and Chemotherapy Become Stronger

DURHAM, N.C. – Because of the way solid tumors adapt the body's machinery to bring themselves more oxygen, chemotherapy and radiation may actually make these tumors stronger.

"In a sense, these therapies can make the tumor healthier," said Mark W. Dewhirst, D.V.M., Ph.D., professor of radiation oncology at Duke University Medical Center. "Unless the treatment is very effective in killing many if not most tumor cells, you are shooting yourself in the foot."

Dewhirst and colleagues Yiting Cao, M.D., Ph.D., of Duke Pathology, and Benjamin Moeller, M.D., Ph.D. have introduced this counter-intuitive idea at recent conferences and in a review article featured in the June issue of Nature Reviews Cancer.

Radiation and chemotherapy do kill most solid tumor cells, but in the cells that survive, the therapies drive an increase in a regulatory factor called HIF1 (hypoxia-inducible factor 1), which cells use to get the oxygen they need by increasing blood vessel growth into the tumor. Solid tumors generally have low supplies of oxygen, Dewhirst explained and HIF1 helps them get the oxygen they need.

The review article concludes that blocking (HIF1) would provide a clear mechanism for killing solid-tumor cells, particularly cells that are proving resistant to radiation or chemotherapy treatments.

source: mary Jane Gor, Duke University Medical Center