Men who eat a lot of red meat have a two-and-one-half-fold greater chance of developing advanced prostate cancer than those who eat less, according to a study published Wednesday by a group of School of Public Health (SPH) researchers.
The study, published in the Journal of the National Cancer Institute, also demonstrates that men with the highest fat intakes have an 80 percent higher chance of developing prostate cancer than men with the lowest intakes.
After responding to questionnaires regarding their diets, men who reported their habits were placed in three groups, according to the quantities of red meat eaten. Those in the highest group were two-and-one-half times more likely to develop prostate cancer.
The study also shows that fat from dairy products, fish and vegetables is not related to the risk of the disease.
Prostate cancer is the most commonly occurring cancer in men, according to the American Cancer Society, and is second only to lung cancer in death rate.
Approximately 165,000 American men will be diagnosed this year with prostate cancer, and 35,000 will die of the disease.
Cancer of the prostate occurs mostly in men over the age of 55, with 80 percent of cases in men over 65. For unknown reasons, Black men have a 40 percent higher chance of developing prostate cancer than white men.
In a statement, Dr. Edward L. Giovannucci, one of the authors of the study, called the finding "exciting" and said that changing men's diets may protect against cancer.
"Although there needs to be a more complete understanding of the causes of prostate cancer," Giovannucci said, "our findings are consistent with the generally accepted belief that progression of the disease, including death, appears to be strongly related to animal fat or other external factors."
"This is more strong evidence that red meat should play a small part in our diet," Giovannucci said.
The causes of prostate cancer are unknown, but doctors have suspected for years that the disease is linked to nutrition. "There are some studies implicating diet, and there are good studies implicating fat in the diet," said urologist Dr. Kenneth I. Wishnow, associate professor of surgery at the Medical School.
The study involved 51,529 male health professionals between the ages of 40 and 75 who participated in the Health Professionals Follow-Up Study. The men completed surveys describing their diets in 1986, and then repeated the forms in 1988 and 1990.
Of all the foods from the questionnaire, bacon, butter, mayonnaise and creamy salad dressing, beef, pork and lamb resulted in the highest correlations with advanced prostate cancer.
While the study only reported a statistical correlation, Wishnow cited the relationship between fat and the level of hormones in the blood as an outgrowth of the study which might require further investigation.
"It's known that hormones tend to contribute to the progression of prostate cancer," Wishnow said. "The diet could potentially influence the level of hormones in the blood, but it needs to be proven."