Eating well-done red meat--whether barbecued, grilled or pan-seared--does not increase a woman's risk of breast cancer, but a diet rich in fish, chicken or turkey may offer some protection against the disease, according to a UC Irvine study released today.
Previous studies of rats suggested that chemicals on and near the surface of red meats cooked thoroughly at high temperatures combine with enzymes in the body to bind with DNA, causing mammary cell cancers.
The UCI study, published in the April issue of Carcinogenesis, examined the meat-eating habits of 394 Orange County women being treated at three clinics for suspicious breast masses from 1995 to 1998. Researchers found no higher incidence of malignancy in women who ate well-cooked red meat, defined as hamburger, beefsteak, pork, bacon and breakfast sausage.
"We found no association between consumption of well-done red meat and breast cancer," said Dr. Ralph J. Delfino, an epidemiologist at UCI's College of Medicine. "However, the greater the amount of all chicken eaten--whether barbecued or pan-fried to any doneness--the less their risk of breast cancer."
Among the women surveyed, 114 subsequently were diagnosed with a malignancy and 280 had benign growths.
Delfino warned that the study must be "interpreted cautiously" because the women studied were a relatively small group of predominately white, middle-class, well-educated women. The conclusions may not apply to minorities or women in other social classes, he said.
"It is really important in epidemiology [to understand] that different populations have different risk profiles," he said. "Frankly, the women we studied probably ate a healthier diet than what is normally consumed in Middle America."
Previous studies of women--particularly one in Iowa--showed a relationship between the doneness of red meat and breast cancer. In that study, though, the women ate considerably more red meat--25% to 50% more a day--than the women in the UCI study.
Delfino and his coauthor, professor Hoda Anton-Culver, who heads the university's epidemiology department, also noted that many factors may be at work in their findings on consumption of white meat, defined as chicken, turkey or fish.
For instance, they said, women who are eating a diet high in chicken may be inclined to other healthful habits, or it may be that the amino acid content of white meat supports proper immune function so that those eating more white meat fight off tumors more effectively.
Another reason for caution is that the study included only women with abnormal breast tissue, and made no comparison with the meat diets of healthy women, Delfino said. UCI now is studying another group of women diagnosed with breast masses and comparing their diet to those of a group of healthy women.
"I am hoping within six months we will have some data that will show if there is a significant difference for those who don't have any breast disease," Anton-Culver said.