Gene Plays Key Role in Prostate Cancer Spread, Study Finds

In the Journal of the National Cancer Institute study, scientists reported evidence that the gene producing a protein called RKIP controls the ability of prostate cancer cells to spread to nearby blood vessels. Once the cancer has spread, doctors say, it is difficult to treat and can kill the patient.

Scientists found that cancer cells in tumors producing a normal amount of RKIP, or Raf kinase inhibitor protein, are unable to spread. Without that protein, however, cancer cells moved beyond the prostate.

“The gene encoding RKIP appears to be… involved in blocking the cell-signaling processes that allow cancer cells to enter the bloodstream,” study author Evan Keller of the University of Michigan Medical School said. “If there is RKIP expression in a tumor, this first important step appears to be less likely.”

The findings in Wednesday’s study may one day help doctors identify which cancers will spread — helping them better advise patients on their treatment options. Currently many patients elect to have their prostate surgically removed to avoid the risk that the cancer could spread.

With better tools to predict how prostate cancer cells will behave, doctors may be able to spare some patients from having a surgery that carries the risk of incontinence, stool incontinence and sexual impotency.

However, the researchers who published the study caution that even though the presence of RKIP can be easily detected, more study of the protein is necessary before tests or treatments can be made available. Scientists might also one day develop gene therapy to replace RKIP — and prevent the disease from spreading — in those whose tumors don’t produce it.

After skin cancer, prostate cancer is the most common form of the disease to strike American men. The American Cancer Society estimates that in 2003 there will be about 220,900 new cases of the disease in the U.S.

Wednesday’s study should help researchers better understand how the disease spreads. However, Keller cautioned that while jumping to the nearby blood vessels is the “first step” in cancer spreading, it is not the only action necessary for cancer to spread in a patient’s body.

“Many cancer cells that enter the bloodstream don’t go on to form successful metastases,” Keller said.

But he predicted that study’s findings will help clarify the complex process that makes some cancers more deadly than others.

“These findings bring home the point that if you can stop even one gene in the cascade, you can slow the process down,” he added.