Postmenopausal women who regularly consume smoked and barbecued meats may be increasing their risk of breast cancer by at least 50 per cent, suggests a new study.
The study, published in the journal Epidemiology, is said to be the first to report and association between lifelong consumption of such meat and breast cancer risk, and must be confirmed in many more studies. The study also does not establish that the link is causal.
The study adds to a growing body of epidemiological studies linking meat consumption, particularly red meat with breast cancer risk. Indeed, Harvard researchers recently reported that eating more than one and a half servings of red per day may double their risk of hormone receptor-positive breast cancer, compared to women who eat less than three servings per week (Archives of Internal Medicine, Vol. 166, pp. 2253-2259).
Over one million women worldwide are diagnosed with breast cancer every year, with the highest incidences in the US and the Netherlands. The National Cancer Institute estimates that 13 percent of American women will develop breast cancer during their lives.
Lead researcher Susan Steck and co-workers from the University of South Carolina in Columbia recruited 1508 women with breast cancer and 1556 healthy controls and estimated their lifetime intakes of grilled or barbecued and smoked meats using interviewer-administered questionnaire data.
No effect was observed for premenopausal women, but a modest increased risk of 47 per cent was observed among postmenopausal women with the highest consumption of smoked and grilled or barbecued meats over their life.
In a subset of postmenopausal women with high consumption of the meats and low fruit and vegetable intake the associated risk of breast cancer was increased to 74 per cent.
"These results support the accumulating evidence that consumption of meats cooked by methods that promote carcinogen formation may increase risk of postmenopausal breast cancer," wrote Steck.
The researchers suggested that the increased risk might be due to the formation of carcinogenic compounds polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs) in or on the surface of well-done meat, cooked at high temperature.
However, when measures of PAHs and HCAs were evaluated using food frequency questionnaires, no observations were observed, "with the possible exception of benzo([alpha])pyrene from meat among postmenopausal women whose tumours were positive for both oestrogen receptors and progesterone receptors."
The incidence of hormone receptor-positive breast cancer is said to be increasing in the US, particularly among women in the 40 to 69 year old bracket. Hormone receptor-negative breast cancer incidence has not been changing.
The study does have obvious limitations, most notably the estimation of lifelong intakes that are susceptible to recall error of the participants. It should also be stressed that the study does not identify the formation of the potential carcinogens as causal, and may be related to other factors, said the researchers, like high fat content of the meat.
If further studies do support these observations the results may have important implications for the prevention of breast cancer, a disease that has many risk factors that are not easily modifiable.
May 2007, Volume 18, Number 3, Pages 373-382
"Cooked Meat and Risk of Breast Cancer-Lifetime Versus Recent Dietary Intake"
Authors: S.E. Steck, M.M. Gaudet, S.M. Eng, J.A. Britton, S.L. Teitelbaum, A.I. Neugut, R.M. Santella, M.D. Gammon