Well-Done Meat Consumption May Increase Prostate Cancer Risk

Two groups of men were recruited for the study: men who were diagnosed with aggressive prostate cancer (Gleason score ≥7; tumor stage ≥T2c; or a prostate-specific antigen level greater than 10 ng/ml at diagnosis) and men who matched the profiles of these prostate cancer patients, who underwent annual medical exams at the collaborating medical institutions, but who had no diagnosis of prostate cancer or of any other non-skin cancer. All men were recruited between 2001 and 2004.

Each man completed a food frequency questionnaire that asked him to recall food consumption over a year. A second questionnaire asked the men about their intake of grilled or barbequed meats and red meat doneness levels.

Researchers were looking to estimate the amount of heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) these men consumed in a year. Both of these chemicals occur when meat, particularly red meat, is cooked at high temperatures. HCAs form when amino acids, sugars, and creatine (a substance found in muscle) react to high temperatures. PAHs are in the flames caused by the fat and juices that drip from meat grilled directly over an open fire. They coat the surface of barbequed steak or hamburgers, for example.  In lab experiments, both chemicals have been found to be mutagenic, which means that they cause changes in DNA that may increase the risk of cancer.

The study’s main findings were as follows:

• Higher intake of ground meat (especially ground beef), liver, and processed meats was associated with an increased risk of aggressive prostate cancer.
• There was a positive association between the consumption of grilled and barbecued meat and the risk of aggressive prostate cancer. In fact, the authors suggest that this method of preparing ground beef, namely by grilling it, may account for the finding that its increased consumption could play a role in the development of prostate cancer.
• Men who ate grilled or barbecued beef that was well done or very well done had about twice the odds of developing aggressive prostate cancer as those who never ate meat or who ate rare or medium-cooked beef.
• Increased consumption of higher fat lunchmeats was also associated with risk of aggressive prostate cancer.

The authors of this research admit that some measurement errors are possible. For example, the men might recall their food consumption inaccurately. Also, the food frequency questionnaire could not possibly track all of the foods, minerals, and vitamins that might affect a man’s prostate cancer risk. This complexity is a drawback in most studies of the role that diet and dietary supplements play in prostate cancer. (See the PCCN pages on diet and supplements.)

Still, other research findings have shown a link between the intake of well-done or very well-done red meat and prostate cancer. Both the Agricultural Health Study and the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial offer supportive evidence, at least for the connection between very well-done meat and prostate cancer risk. Other forms of cancer seem to be linked to meat consumption as well.  Dr. Rachel Thompson of the World Cancer Research Fund comments:

Looking at cancer overall, there is already a good reason to watch the amount of red and processed meat in your diet. There is very strong evidence that both red and processed meats increase risk of bowel cancer.

And just today, Japan’s National Cancer Center reported on a study that found a connection between eating large amounts of red meat and a greater risk of colon cancer; it is advising that the consumption of beef and pork be cut back.

In the face of this research, men at high risk for prostate cancer because of family history might consider modifying their diets and saving those barbequed steaks for special occasions.

References:
John S. Witte and colleagues, 2011, “Impact of meat consumption, preparation, and mutagens on aggressive prostate cancer,” PLoS one.

Fiona Macrae, 24 November 2011, “Well-done steaks double prostate cancer risk,” Daily Mail.