Recent use of some birth control pills may increase breast cancer risk

Women who recently used birth control pills containing high-dose estrogen and a few other formulations had an increased risk for breast cancer, whereas women using some other formulations did not, according to data published in Cancer Research, a journal of the American Association for Cancer Research.

"Our results suggest that use of contemporary oral contraceptives [] in the past year is associated with an increased risk relative to never or former oral contraceptive use, and that this risk may vary by oral contraceptive formulation," said Elisabeth F. Beaber, PhD, MPH, a staff scientist in the Public Health Sciences Division of Fred Hutchinson Cancer Research Center in Seattle, Washington.

"Our results require confirmation and should be interpreted cautiously," added Beaber. "Breast cancer is rare among young women and there are numerous established health benefits associated with oral contraceptive use that must be considered. In addition, prior studies suggest that the increased risk associated with recent oral contraceptive use declines after stopping oral contraceptives."

In a nested case-control study of 1,102 women diagnosed with breast cancer and 21,952 controls, Beaber and colleagues found that recent oral contraceptive use increased by 50 percent, compared with never or former use. All study participants were at Group Health Cooperative in the Seattle-Puget Sound area. Patients received a cancer diagnosis between 1990 and 2009.

Birth control pills containing high-dose estrogen increased breast cancer risk 2.7-fold, and those containing moderate-dose estrogen increased the risk 1.6-fold. Pills containing ethynodiol diacetate increased the risk 2.6-fold, and triphasic combination pills containing an average of 0.75 milligrams of norethindrone increased the risk 3.1-fold.

Birth control pills containing low-dose estrogen did not increase breast .

About 24 percent, 78 percent, and less than 1 percent of study controls who were recent oral contraceptive users filled at least one prescription in the past year for low-, moderate-, and/or high-estrogen dose , respectively, according to Beaber.

Unlike most previous studies that depended on women's self-report or recall, which may cause bias, Beaber and colleagues used electronic pharmacy records to gather detailed information on oral contraceptive use including drug name, dosage, and duration of medication.

add to favorites email to friend print save as pdf

Related Stories

Recommended for you

How much overdetection is acceptable in cancer screening?

9 hours ago

People have highly variable views on how much overdetection is acceptable in cancer screening, finds a UK survey in The BMJ this week. The authors say invitations for screening "should include clear information on the li ...

Protein may be key to cancer's deadly resurgences

18 hours ago

Tumor recurrence following a period of remission is the main cause of death in cancer. The ability of cancer cells to remain dormant during and following therapy, only to be reactivated at a later time, frequently ...

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.