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Study Debunks Added Cancer Risk With 'Pill'

Health: Biggest survey ever removes some doubt for 80% of women born after 1945 who were probable users of contraceptives.


Oral contraceptives do not increase the risk of breast cancer in women, regardless of age, race, weight, age, the variety of contraceptive used, or any other factors, according to the largest study ever to examine the possible hazards of the "pill."

A 1996 survey of several small studies had suggested that using the pill produced a small increase in breast cancer risk, but the massive new study published today) in the New England Journal of Medicine found no increased risk at all for women who do not smoke.

The findings lift a cloud of doubt that has hovered over the 80% of American women born after 1945 who have taken the pill at some time in their lives.

"This is very good news," said Dr. Polly Marchbanks of the Centers for Disease Control and Prevention, who led the study. "This is a very important issue because of ... the high prevalence of oral contraceptive use."

In fact, this may have been the researchers' last chance to demonstrate the safety of the pill because there are no longer enough women who haven't used it to provide an effective comparison group, added Dr. Robert Spirtas of the National Institute of Child Health and Human Development.

The pill is not completely without risk, however. In rare cases, it can cause blood clots, liver cancer and heart attacks in women who smoke. In contrast, oral contraceptives have also been shown to reduce the risk of ovarian and endometrial cancer by about 40%.

"But for most women, the benefits of avoiding pregnancy, with its attendant health risks, clearly outweigh these side effects," Dr. Kathy J. Helzlsouer and Dr. Nancy E. Davidson of Johns Hopkins University wrote in an editorial in the same journal.

In light of the new results, they said, researchers should shift their concern from worrying about the possible adverse effects of existing contraceptives to the development of newer versions that protect against breast cancer.

About 200,000 American women are diagnosed with breast cancer each year and 40,000 die from it. The incidence has been increasing since the 1980s, and some researchers had feared that the rise was linked to the growing use of oral contraceptives because breast cancer is known to be linked to sex hormones. The new findings mean that the search for causes of that increase will have to shift to other directions.

In the new analysis, Marchbanks and her colleagues studied 4,575 women who had developed breast cancer and 4,682 closely matched women who had not.

The women, aged 35 to 64, were questioned closely about their use of the drugs, as well as about a variety of other potential complicating factors. About 65% of the women were white and 35% black.

The team found that 77% of the women with cancer had used oral contraceptives, compared to 79% of those without the disease--an insignificant difference.

The team found no link between use of the pill and the development of breast cancer, no matter how long women had used the contraceptive, when they started it, how long ago they quit, or how large an estrogen dose they had received. There was also no increased risk among women who were obese or among women with a family history of breast cancer. No racial differences in risk were observed.

"Every which way you looked at it, there was no increased risk" associated with contraceptive use, Helzlsouer said.

The findings are "very reassuring," said Dr. Duane Alexander, director of the NICHD, which sponsored the study. "Women between the ages of 35 and 64 are more likely to develop breast cancer than are younger women," he said, and the new study shows that the pill does not increase their risk.

The sole exception to the findings was among women between the ages of 45 and 64 who are taking the pill to alleviate symptoms of menopause or to reduce their risk of ovarian and endometrial cancer and benign breast disease.

The team found a slightly increased risk of breast cancer among these women, but the number of women studied in this group was too small to reach any firm conclusions and the increased risk was not statistically significant.

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