Study is good news to radiation recipients

DURHAM, N.C., Aug 15, 2005 (United Press International via COMTEX) -- A Duke University study published in the August issue of Cancer Cell may bring good news for cancer patients who undergo radiation therapy each year.

Duke University Medical Center scientists say they now have a better understanding of the complex affects of radiation on tumor biology and that specific radiation treatment regimens may enhance the effectiveness of radiotherapy, even in difficult to treat tumors.

In an earlier study, Dr. Mark Dewhirst and his Duke colleagues reported radiation treatment increases hypoxia-inducible factor-1 levels in tumors and elevated HIF-1 can promote the resistance of tumors to radiation because it has a protective effect on tumor blood vessels.

Now Dewhirst and his team say blocking HIF-1 also affects multiple aspects of tumor biology in a manner that depends strongly on the local environment of the tumor cells.

For proximal tumor cells close to blood vessels and, well oxygenated, HIF-1 is unlikely to be activated, and its inhibition will probably not have any effect.

However, for distal tumor cells that are both oxygen starved and lacking access to nutrients because they are farther away from the tumor vasculature, HIF-1 inhibition may actually lead to significant resistance to radiation treatment.