Prostate Cancer May Have Roots in Genetic Defect

Prostate cancer may be closely linked to a genetic defect that hampers the body’s defenses against environmental carcinogens, researchers from Johns Hopkins University have found.

Writing in the latest issue of Proceedings of the National Academy of Sciences, the researchers said they had found what appeared to be the most common genetic flaw linked to the cancer, which strikes about 165,000 American men yearly.

“I think we’d have to view this as a tremendous clue,” said the leader of the study, Dr. William Nelson, an assistant professor of oncology and urology.

“It’s present in almost all of the (prostate) cancers, so it’s got to be telling us something,” Nelson said in a telephone interview. “I think the key is, are we going to be clever enough to figure out what it means.”

The genetic defect found in nearly all of the 91 prostate cancers studied blocked production of an enzyme that guards against cancer-causing substances in the environment. The flaw was not present in the prostates of healthy individuals.

“A deficiency in the production of this enzyme may render normal prostate cells more vulnerable to carcinogens in the environment,” Nelson said.

The flaw discovered by the researchers is in the molecular makeup of one of the strands of the DNA, or genetic blueprint, rather than in the order in which the strands rest.

That implies that the flaw is potentially treatable with drugs, Nelson said. He said scientists working in a laboratory were able to use drugs to make the problem gene work again.

“Whether this can ever be done in people or not is not clear,” he said.

Earlier studies have shown that high-level production of similar enzymes is stimulated by consumption of “cruciferous” vegetables such as broccoli, cauliflower and Brussels sprouts.

Nelson said it is too early to say whether a change in diet can help.

He also said it may be possible to use the enzyme to screen substances thought to be possible carcinogens.