Caloric intake has “important” etiologic role in breast cancer

Confirming studies in animals, the results of a retrospective study in anorexic women indicate that caloric restriction at an early age protects against invasive breast cancer.

“Our observations suggest an important role for caloric intake in the etiology of breast cancer,” researchers write in the March 10th issue of the Journal of the American Medical Association.Among some 7300 Swedish women hospitalized for anorexia nervosa before their 40th birthday between 1965 and 1998, researchers noted a significant 53% decrease in breast cancer incidence compared with that expected in the general Swedish population of women.The incidence of breast cancer was 23% lower in nulliparous women with anorexia nervosa and 76% lower in parous women with anorexia, they report.”We have known for decades that restricting caloric intake in animals is one of the most effective ways to reduce cancer risk,” Dr. Karin B. Michels from Harvard Medical School in Boston, said in a telephone interview with Reuters Health. It’s been unclear, however, whether the same is true in humans.”Our study tells us that the animal model also holds in the human and that apparently diet is important for breast cancer risk, at least as far as caloric intake is concerned, and that it is probably more pronounced during earlier phases of life,” Dr. Michels said.”There is a tendency now in breast cancer research to go back to earlier phases of a woman’s life because we haven’t been very successful in pinning down dietary risk factors for breast cancer in later phases,” Dr. Michels explained.”A lot of studies have targeted dietary intake during ages 50 and 60 but those studies have not yielded much,” she continued. “Our study suggests that maybe we should be looking at the role of diet in puberty or adolescence and breast cancer.”Dr. Michels and colleagues will next explore the underlying mechanisms of the apparent protective effect of caloric restriction on breast cancer. “There are two main hypotheses,” she said. One, that caloric restriction influences breast cell growth and development, and, two, that lower levels of estrogen and growth factors induced by caloric restriction are involved.(Source: JAMA 2004;291:1226-1230: Reuters Health: Megan Rauscher: March 2004: Oncolink)