Cancer Advances: Healthy Diet Shows No Effect on Short-term PSA Levels

From the September 1, 2002 issue of the Journal of Clinical Oncology.In an effort to determine a man's risk of developing prostate cancer, physicians often look at his prostate-specific antigen (PSA) levels. The prostate-specific antigen is a protein in the blood that at high levels often indicates the presence of prostate cancer. Over the last several years, there has been some evidence suggesting that a low-fat, high-fiber diet may offer protection against developing cancer. In an effort to determine if a healthy diet had an impact on PSA levels, researchers at Memorial Sloan-Kettering Cancer Center, the National Cancer Institute, and seven other centers conducted a study with more than 1,300 men without prostate cancer. In the four-year study, men without prostate cancer received either intensive nutritional counseling to consume a diet low in fat and high in fruits, vegetables and fiber, or were given a brochure outlining healthy dietary recommendations. Researchers found that diet did not have any effect in reducing prostate cancer risk as measured by the PSA serum level over the four-year study, but stressed that a healthy diet remains important. During the study, the PSA levels of men in both groups were similar and virtually the same number of men in each group developed prostate cancer: 22 in the intensive nutritional counseling group and 19 in the nutritional brochure group. Dr. Moshe Shike, the lead study author and Director of the Memorial Sloan-Kettering Cancer Center's Prevention Program says that these findings should not be viewed as definitive evidence that diet has no preventive impact on a man's risk of developing prostate cancer. "It is possible that diet could inhibit cancer growth without drastically affecting PSA levels, and it may be that dietary patterns may need to be sustained over a long period of time to have any effect on cancer risk." Dr. Shike said that while there are no conclusive studies showing that diet plays a decisive role in preventing any form of cancer, people should continue following their physician's dietary recommendations. He recommends people limit calories and eat a fruit- and vegetable-enriched, low-fat diet, with fat intake making up 20% to 25% of a person's daily intake of calories.