WELL-DONE MEAT INTAKE AND THE RISK OF BREAST-CANCER

Background: Heterocyclic amines, mutagens formed in meats cooked at hi gh temperatures, have been demonstrated as mammary carcinogens in anim als. We conducted a nested, case-control study among 41 836 cohort mem bers of the Iowa Women's Health Study to evaluate the potential role o f heterocyclic amines and intake of well-done meat in the risk fur hum an breast cancer. Methods: A questionnaire was mailed to individuals i n the cohort who had breast cancer diagnosed during the period from 19 92 through 1994 and a random sample of cancer-free cohort members to o btain information on usual intake of meats and on meat preparation pra ctices, Color photographs showing various doneness levels of hamburger , beefsteak, and bacon were included, Multivariate analysis was perfor med on data from 273 ease subjects and 657 control subjects who comple ted the survey. Results: A dose-response relationship was found betwee n doneness levels of meat consumed and breast cancer risk. The adjuste d odds ratios (ORs) for very well-done meat versus rare or medium-done meat were 1.54 (95% confidence interval [CI] = 0.96-2.47) for hamburg er, 2.21 (95% CI = 1.30-3.77) for beef steak, and 1.64 (95% CI = 0.92- 2.93) for bacon. Women who consumed these three meats consistently ver y well done had a 4.62 times higher risk (95% CI = 1.36-15.70) than th at of women who consumed the meats rare or medium done. Risk of breast cancer was also elevated with increasing intake of well-done to very well-done meat. Conclusions: Consumption of well-done meats and, thus, exposures to heterocyclic amines (or other compounds) formed during h igh-temperature cooking may play an important role in the risk of brea st cancer.