Health News

Heparin May Reduce Cancer's Spread

March 12, 2001 -- A drug commonly used to prevent blood clotting may discourage cancer from spreading, according to a new study. The drug, called heparin, appears to prevent blood cells from sticking to tumor cells that are migrating through the bloodstream.

When cancer is detected early enough, the chances of recovering from it are very good. However, if the cancer has spread through a process called metastasis, where small cancers move to distant sites in the body, a cure is usually very difficult. Metastasis is one of the most common reasons for cancer-related death.

Research on animals that took place in the 1960s and '70s suggested that heparin, a drug given by injection, might help prevent cancer from spreading. Unfortunately, this research was put on the back burner when similar drugs taken by mouth failed to show a similar effect. This study, however, demonstrates that heparin acts differently from the drugs taken orally, and it is this different action that is responsible for its potential ability to discourage the spread of cancer throughout the body.

Normally, cancer spreads when pieces of the original tumor break off and travel through the bloodstream to other parts of the body, where they start the growth of a new tumor. During their travels though the bloodstream, these tumor cells are protected from the body's immune system because platelets -- one of many types of cells in the bloodstream -- stick to them and prevent the immune system from recognizing them.

This study on mice shows that heparin prevents platelets from sticking to the cancer cells, making them more vulnerable to the immune system's natural cleanup action. The research is published in the March 13 issue of the medical journal Proceedings of the National Academy of Sciences.

"The use of heparin to prevent tumor metastasis in humans should be revisited in the light of the new explanation for its action," senior author Ajit Varki, MD, tells WebMD. "[However,] we have only done studies in mice. A controlled clinical study in humans needs to be done."

Varki is professor of medicine and director of the Glycobiology Research and Training Center at the University of California, San Diego. His research received support from the National Cancer Institute.