Study: Oral Contraceptives Do Not Increase Breast Cancer Risk, Lower Heart Disease Risk (dateline November 30, 2004)
A recent study finds that women who take oral contraceptives (i.e., birth control pills), are not at greater risk of developing breast cancer, compared to women who do not them. In the largest womens health study to date, women who took oral contraceptives for at least four years were 7% less likely to develop any type of cancer and were at lower risk of developing ovarian or uterine cancers. Approximately 16 million women currently use oral contraceptives and over 45 million women have taken "the Pill" at some point in their lives. While recent studies have shown that taking hormones later in lifearound menopausemay increase breast cancer risk, the results of the current study can reassure women that oral contraceptives taken among women of child-bearing age do not increase breast cancer risk.
Dr. Rahi Victory of Wayne State University and colleagues presented results of the study at the 60th Annual Meeting of the American Society for Reproductive Medicine in Philadelphia, Pennsylvania. The study investigated several factors, including conception, cancer, and cardiovascular health.
In an analysis of 67,000 medical records obtained from the National Institutes of Healths (NIH) Womens Health Initiative database, the researchers found a strong relationship between oral contraceptive use and reduced risk of any cardiovascular disease, including angina (chest pain), stroke, high cholesterol, and heart attack.
In a similar analysis, the researches found no effect of oral contraceptive use on the risk of developing breast cancer, colon cancer, or bladder cancer. In fact, prolonged oral contraceptive use (four years or longer) was associated with a 7% reduction in any type of cancer. Women in the study who took oral contraceptives for four years or more had 42% lower risk of developing ovarian cancer and a 30% lower risk of developing uterine cancer.
"These studies show what a great resource the Womens Health Initiative database is. We are pleased investigators are continuing to delve into it in greater depths," said Marian Damewood, M.D., President of. American Society for Reproductive Medicine (ASRM), in an ASRM press release. "These results are very interesting, but need further review. As always women should ask their gynecologists about what these results might mean for them before making any decisions about their own health."
The current study confirms the results of previous research that oral contraceptives do not affect a womans chances of developing breast cancer. In a 2002 study of over 9,000 women, researchers from the Centers for Disease Control and Prevention also found that that oral contraception does not increase breast cancer risk in women who have taken "the Pill" in the past.
The belief that oral contraceptives cause breast cancer stems from the fact that the Pill contains hormones, including estrogen and/or progesterone (estrogen has been linked with higher risk of breast cancer in menopausal women who take hormone replacement therapy). Birth control pills manufactured prior to 1975 contained significantly higher amount of these hormones, but todays versions of the Pill have very low levels of hormones.
While oral contraceptives do not cause breast cancer in past users, birth control pills are associated with a number of side effects for current users. While most side effects are mild, serious risks include blood clotting, heart attack, stroke, gallbladder disease, and in rare cases, liver tumors. Smoking greatly increases the risk of heart attack and stroke among oral contraceptive users. The Pill is also associated with several beneficial effects in addition to preventing pregnancy. These include a possible reduction in menstrual symptoms, reduced risk of acute pelvic inflammatory disease, and a lower risk of ovarian cancer and endometrial cancer (cancer of the uterine lining).