The Los Angeles Times on Monday examined the association between obesity and the risk of developing breast cancer. According to the Times, a high body mass index for women of childbearing age appears to lower the risk of developing breast cancer; however, the risk increases for girls who have a high BMI before puberty or for postmenopausal women who have a high BMI. A study published last week in the Nov. 27 issue of the Archives of Internal Medicine found that the association between fat and a lower risk of developing breast cancer was stronger earlier in a woman's life, the Times reports. The results of the study "square with the current understanding of how breast cancer develops," according to the Times. Studies have found that women who have a lower lifetime exposure to estrogen have a lower risk of developing breast cancer. In premenopausal women, fatty tissue produces low levels of estrogen that "feeds back on the ovaries and dampens their cyclical release of estrogen," thus subtracting from the total amount of estrogen to which they are exposed, the Times reports. Postmenopausal women have low levels of estrogen, "thus, any extra estrogen from fat is contributing to their total load, not subtracting," according to the Times. "It's like taking a little birth control pill," Anne McTiernan, director of the Prevention Center at the Fred Hutchinson Cancer Research Center, said, adding, "Obese and overweight women are not ovulating normally." In addition, obese and overweight premenopausal women are not producing progesterone -- a hormone associated with a higher risk of developing breast cancer -- in the same way that women of regular weight are, McTiernan said. According to the Times, health experts say the association of developing breast cancer and obesity should not prompt premenopausal women to gain weight. Amtul Carmichael, a breast cancer researcher at Russells Hall Hospital in Dudley, England, said, "[O]bese premenopausal women will become obese postmenopausal women," adding, "Obese women are two to three times more likely to die from breast cancer, and that's common to both pre- and postmenopausal women." In addition, treatments such as chemotherapy might be less effective for obese women because chemotherapy is based on weight, but physicians might give obese women slightly lower doses to avoid toxicity, Carmichael said (Beckman, Los Angeles Times, 12/4).
Obesity and breast cancer
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