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Pill not linked to breast cancer
©Washington Post A major new study offers reassuring news on breast cancer for the 80 percent of U.S. women born after 1945 who have ever taken birth control pills: Past or present use of oral contraceptives doesn't increase a woman's breast cancer risk. That conclusion held true whether women in the study had taken the pills as teens or adults, whether they took birth control pills that were high or low in estrogen, whether they took them for months or years, whether they were white or black, and even whether they had a family history of breast cancer. Because an earlier analysis of many smaller studies had suggested a possible small increase in breast cancer risk among users of oral contraceptives, the large government-funded study was designed to lay the question to rest -- and for once, experts said, a study seems to have nearly succeeded in doing just that. "Every which way you looked at it . . . there's no risk" of breast cancer associated with birth control pills, said Kathy Helzlsouer, an epidemiologist at Johns Hopkins and co-author of a commentary accompanying the findings in today's New England Journal of Medicine. "We do believe this study is very good news," said Polly Marchbanks, an epidemiologist with the federal Centers for Disease Control and Prevention in Atlanta who led the research. "This is an especially important issue because of the serious nature of breast cancer and the high prevalence of oral contraceptive use." Since breast tissue responds to sex hormones such as those in the pill, researchers had thought it was possible oral contraceptives could increase the risk for breast cancer. Marchbanks said the only women for whom the issue remains somewhat unresolved are those between the ages of 45 and 64 who take oral contraceptives before or during menopause -- for birth control, to alleviate common symptoms such as irregular menstrual periods, or to reduce their risk of other conditions such as ovarian cancer, endometrial cancer and benign breast disease. Among women in that age group, the study found evidence of a small elevation in breast cancer risk associated with pill use. However, the use of oral contraceptives in this population is a relatively new phenomenon, Marchbanks said, and the number of study participants in that age group who were taking the medications was small. Among younger women, use of oral contraceptives at some point during the reproductive years has become almost universal, said Robert Spirtas, chief of the contraception and reproductive health branch at the National Institute of Child Health and Human Development. "It's now becoming unusual for a woman to go through a lifetime without ever taking (birth control) pills," he said, adding that repeating the study would probably be impossible in the future because a comparison group of nonusers couldn't be found. For the study, researchers in five U.S. cities enrolled 4,575 women with breast cancer who were between 35 and 64, and 4,682 healthy women who were of similar ages and lived in the same neighborhoods. Sixty-five percent of participants were white and 35 percent were black. Study participants were interviewed about their use of oral contraceptives and other hormones, reproductive and health history, family history and other characteristics. Similar proportions of the women with cancer and the comparison group (77 percent versus 79 percent) had used oral contraceptives. There was no difference in breast cancer risk among those who had ever used the pills and those who hadn't. The researchers found no evidence of increased risk among women who had taken higher-dose pills, among those who had begun taking them before the age of 20, or among those who had used them before their first full-term pregnancy. There were no consistent differences in risk between black and white women. There was no heightened risk associated with pill use among women who were obese or among those who had a family history of breast cancer (although family history and obesity are risk factors for the disease.) "Our study provides strong evidence that past oral contraceptive use does not increase the risk of breast cancer later in life," Marchbanks said. Oral contraceptives reduce the risk of ovarian and endometrial cancer and may increase the risk of cervical cancer. The pills increase the risk of blood clots in the legs and lungs, strokes and liver cancer, although such events are rare. In women over 35 who smoke, oral contraceptives also increase the risk of heart attacks. Because they provide such effective protection against pregnancy, "the health benefits of oral contraceptives far exceed the health risks . . . for most healthy women who do not smoke," Marchbanks said. Dr. Claudine Isaacs, clinical director of the breast cancer program at Georgetown University Hospital, said the latest study did not look far enough to say with certainty whether the pill raises the risk for women whose relatives have had the disease. For one thing, women were asked only if their mother or any sister or daughter had breast or ovarian cancer, not whether it had been found in any aunts, cousins or grandmothers, Isaacs said. "I think we still have to be a little cautious about women with a strong family history, or who we know have mutations. Studies are going to be coming out shortly about those," she said. But, she said, the latest findings should reassure the vast majority of women. "I think this is a definitive study," she said. -- Information from the Associated Press was used in this report.
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