WEDNESDAY, June 26, 2002 (HealthDayNews) -- Birth control pills will not increase a woman's risk of getting breast cancer later in life, and they never have.
That's the comforting conclusion of a new study showing that the estrogen in oral contraceptives doesn't take a toll on the breasts once women stop using them.
Birth control pills may slightly elevate a woman's likelihood of developing breast cancer while she's taking them. However, these women are typically young and at very low risk for the disease to begin with, and the effect fades once they are stopped.
"This study provides strong evidence that past use of oral contraceptives does not increase the risk of breast cancer," said Polly Marchbanks, an epidemiologist at the Centers for Disease Control and Prevention and a co-author of the paper.
The findings will appear in tomorrow's issue of the New England Journal of Medicine.
Birth control pills were introduced in the early 1960s, and eight in 10 American women born since 1945 have taken them at some point in their lives. Currently, more than 10 million women between the age of 15 and 44 use the contraceptive method.
The Pill loosely mimics the hormonal environment of pregnancy and prevents ovulation. It initially contained high doses of estrogen and another hormone-like substance called progestin. Now, birth control pills have sharply lower doses of estrogen to mute the hormone's side effects, and some forms contain the progestin only.
Long-term use of estrogen by itself is known to cause uterine cancer. And since estrogen can spur abnormal growth of breast tissue, some scientists were concerned it might also be linked to breast tumors.
A review of 54 much earlier studies found that current or recent birth control pill users had a slightly higher risk of breast cancer than women who'd never used the birth control method. However, those studies found no consistent evidence of such an effect in past users.
Still, Robert Spirtas, a contraceptive expert at the National Institute of Child Health and Human Development, says the previous reports hadn't included older women, in whom the disease is more common, because they didn't have access to the Pill when they were in their reproductive prime.
The new study looked at 4,575 women, aged 35 to 64, with breast cancer and 4,682 similarly aged women without the disease. Roughly a quarter of women in each group had never been on the Pill.
Reassuringly, the researchers found no changes in breast cancer risk from the various formulations or doses, or in longer use of the contraceptives.
Only 372 women in the study were currently taking the Pill, too small a number to draw conclusions from, says Spirtas, whose agency helped fund the research. Even so, there didn't seem to be an elevated risk of breast cancer among these women, either.
A previous study found Pill users with a close female relative with breast cancer had triple the risk of developing the disease as those who didn't use the contraceptives. However, the latest study found no such association.
Spirtas says the new study is just the first to come from this group of women. He and his colleagues have other questions to answer, including, for example, whether the combination of oral contraceptives and hormone replacement therapy leads to an increased risk of breast cancer over time.
While the pill is considered extremely safe, it can cause serious and potentially deadly side effects in some women. These include circulatory problems like heart attacks, strokes and blood clots.
Dr. Paul Blumenthal, a women's health expert at Johns Hopkins University, calls the new study "yet another affirmation of the long-term safety of oral contraceptives." While many women believe that the Pill causes cancer -- not only in the breast but in the uterus, too -- "the risk is only putative. It doesn't exist in reality."
What To Do
For more on the Pill and other forms of contraception, try the Planned Parenthood Federation of America or the Feminist Women's Health Center.
