New study adds to evidence that taking oral contraception does not increase
risk of breast cancer
Scott Gottlieb New York
A new study shows that older women who have used oral contraceptives are no
more likely to develop breast cancer than those who have not, bolstering a
growing body of evidence that no link exists.
But researchers cautioned that the new findings were limited to the age group
studied and that more research was warranted for younger women.
The study looked at nearly 9300 women aged 35 to 64. About half of the women
had developed breast cancer in the middle to late 1990s. The rest were healthy
controls.
Interviews with the women showed that similar proportions of these two groups
had used contraceptives (79% of the group without cancer, 77% of the group with
cancer). The relative risk was 1.0 (95% confidence interval 0.8 to 1.3) for
women who were currently using oral contraceptives and 0.9 (0.8 to 1.0) for
those who had previously used them.
The risk did not increase with longer periods of use or with higher doses of
oestrogen, and the results were similar among white and black women, among women
with a family history of breast cancer, and among those who had begun using oral
contraception at a young age (New England Journal and Medicine
2002;346:2025-32).
The exception to these findings was among women aged 45 to 64 who were 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 be significant.
The study focused on older women because of the higher incidence of breast
cancer in that age group. The findings essentially matched the results of a
major study in 1986 that also showed no association between oral contraceptives
and breast cancer.
"We conducted the study to resolve the longstanding concern," said Dr Robert
Spirtas, chief of the National Institute of Child Health and Human Developments
Contraception and Reproductive Health branch and one of the authors of the
study. "Our study provides yet more scientific proof that there isnt an
association."
In an accompanying editorial, Dr Kathy Helzlsouer and Dr Nancy Davidson of
Johns Hopkins University write that "for most women, the benefits of avoiding
pregnancy, with its attendant health risks, clearly outweigh these side
effects."
But they noted that oral contraceptives could also have other adverse
effects, including pulmonary embolism, strokes, liver cancer, and, among smokers
who are over age 35, heart problems. Women who have a positive test result for
the human papillomavirus are also at increased risk of cervical cancer.
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