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Prostate cancer is the second leading cause of cancer death in American men. (Lung cancer is first.) In 2002, doctors will tell an estimated 189,000 men that they have the potentially fatal disease.
The PSA test has emerged as a premier tool in diagnosing prostate cancer. PSA, a protein produced by prostate cells, is frequently present at elevated levels in the blood of men who have prostate cancer. But new studies suggest there may be something even better. Cancer researchers have identified a new genetic culprit, a gene called AMACR (x-methylacyl-CoA racemase) that triggers production of a specific protein found only in cancer cells.
"In our studies, the over-expression of AMACR turned up in 90% of prostate cancers," says William B. Isaacs, Ph.D., professor of urology and oncology at the Johns Hopkins University Kimmel Cancer Center in Baltimore.
The AMACR gene was first revealed as a potential prostate cancer marker two years ago by researchers in Massachusetts. Hopkins scientists and a research team at the University of Michigan Medical School have since published independent studies further identifying AMACR as one of the most consistent biological markers known for prostate cancer.
The findings suggest that AMACR could help pinpoint early prostate cancer and enhance diagnostic accuracy. Researchers are now looking for AMACR in a much larger group of prostate tissue samples. They envision the future development of a blood test for the gene that could reduce the need for needle biopsies of the prostate.
"Since AMACR enzymatic activity is not found in most normal tissues, it could be used todevelop molecular probes for noninvasive detection of prostate cancer," says June Luo, Ph.D., lead author of the Johns Hopkins study.
The protein produced by AMACR helps the body metabolize certain fatty acids, such as those found in dairy products and beef. Researchers caution that the link, if any, between an overexpression of AMACR and a man's diet warrants further study.
Previous studies have shown that men who eat a lot of red meat have an increased risk of prostate cancer. Other risk factors include age, race, nationality, activity and family history. A 70-year-old is 12 times more likely to get prostate cancer than a man 20 years younger. African-American men are at the highest risk and are twice as likely to die from the disease than white males.
According to the American Cancer Society, eliminating high-fat foods and loading up on fruits and vegetables may help a man reduce his risk. Bread, cereals, grain products, rice, pasta, and beans are also recommended. Watermelon grapefruit and tomato (raw or cooked) products contain an antioxidant called lycopene that is believed to lower prostate cancer risk.
