When it comes to eating meat, a guy's choice of what he eats and how it is cooked may affect his risk of having advanced prostate cancer, a new study says.
Men in the study who ate more than 1.5 servings of pan-fried red meat per week were 30 percent more likely to have advanced prostate cancer than were men who rarely ate pan-fried red meat. And men who every week ate more than 2.5 servings of red meat cooked by any high-temperature method — including broiling and grilling — were 40 percent more likely to have advanced prostate cancer than were men who rarely did so.
The findings are not sufficient to make dietary recommendations, and more research would be needed to validate the results, said study researcher Mariana Stern, an epidemiologist at the University of Southern California's Keck School of Medicine.
Still, "to be on the safer side, men should try to limit the intake of pan-fried red meat," Stern said.
The findings were published online July 20 in the journal Carcinogenesis.
Red meat & cancer
The National Cancer Institute estimates 242,000 U.S. men will be diagnosed with prostate cancer this year, while 28,000 prostate cancer patients will die.
Advanced prostate cancer, in which the disease has spread to distant sites in the body, accounts for just 4 percent of all cases. However, that disease is particularly deadly. While nearly everyone with cancer that is confined to the prostate can expect to live at least five years, only 28 percent of those with advanced disease live that long, according to NCI statistics.
Surveying men in Los Angeles and San Francisco, Stern and her colleagues examined the red-meat eating habits of nearly 1,900 prostate cancer patients — including 1,100 whose disease had advanced beyond the prostate gland — and 1,096 men without prostate cancer.
The reason why red meat cooked at high temperatures may increase the risk of advanced prostate cancer is that such meat contains compounds called polycyclic aromatic hydrocarbon (PAHs) and heterocyclic amines (HCAs). Both have been shown to cause cancer in animals, Stern said, noting that both are also found in cigarette smoke.
PAHs form when fat is cooked at high temperatures. For example, when meats are grilled, fat drips in the flames, and the rising smoke deposits PAHs on the meat. HCAs form when sugars and other molecules in the meat are heated. With higher temperatures and longer cooking times, more HCAs form.
"There is strong evidence that PAHs and HCAs cause cancer," Stern said. "There is increasingly suggestive evidence that PAHs and HCAs that accumulate in meats may contribute to certain cancers; prostate is one of them."
Cook methods matter
Previous studies have yielded mixed findings: Some showed a link between red-meat consumption and prostate cancer, and others found no increased cancer risk. Stern said the new study is different because researchers used a detailed questionnaire to accurately assess meat types, cooking methods, and level of "doneness" (rare, well-done, etc.) using colored photographs.
She noted that the researchers found that when men's total red meat consumption, or total processed red meat consumption, was considered, there were no link with an increased risk of prostate cancer. It was only when cooking methods were considered that a link became apparent.
The findings generally show, in terms of increasing advanced prostate cancer risk, that pan-frying meat is worse than grilling it, Stern said. Additionally, eating hamburgers is worse than eating steak – possibly because burgers attain higher internal and external temperatures, or because of their composition, she said.
The study also linked pan-frying poultry with an increased risk of advanced prostate cancer, whereas eating three to four servings of baked poultry per week was associated with a lower risk.
It's not likely that the lowered risk from eating poultry would be due to "the replacement effect" of eating less red meat, Stern said, because the researchers took red meat consumption into account. Further research would be needed to learn how poultry affects prostate cancer risk.