Studies link pill to increased heart risks; but positives still outweigh negatives
■ Oral contraceptives may also slightly increase chance of cervical cancer, but experts say these papers are not reason enough to discontinue it.
By Victoria Stagg Elliott — Posted Dec. 10, 2007
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Hormonal birth control pills may increase markers of cardiovascular disease risk and the chance of developing cervical cancer, according to a handful of studies published and presented at medical meetings within the past month. Experts say, however, that while these studies help paint a more complete picture of the effects of this form of contraception, the positives still outweigh the negatives.
"These [findings] should not change the way oral contraceptives are prescribed," said Nieca Goldberg, MD, medical director of New York University's Women's Heart Program.
With regard to cardiovascular disease, a pair of papers presented at the American Heart Assn. Scientific Sessions in Orlando, Fla., last month suggested that oral contraceptives combining estrogen and progestin increased arterial plaque and levels of C-reactive protein. Researchers analyzed data from a population-based sample of people in Belgium and found these hormones tripled CRP. Taking them for 10 years increased plaque by 20% to 30%.
Experts praised the studies for shining a light on women's heart health and reinforcing the concept that female hormones do not protect this organ. Medical societies and health advocates have become more vocal about such issues in the wake of the Women's Health Initiative. That project proved that hormone therapy was not the way to prevent coronary artery disease and demonstrated that other strategies needed to be devised. Cardiologists are hoping these papers will increase the number of women who have cardiovascular risk factors assessed.
"Women should continue to take oral contraceptives, but this is encouraging the medical community to think about heart and vascular disease in women much earlier," said Jennifer H. Mieres, MD, who moderated the news conference announcing the findings. "And young women need to think about blood pressure control and a heart-healthy lifestyle."
Dr. Mieres is also an associate professor at New York University School of Medicine.
The other side
But some questioned the significance of these findings. For starters, these studies were retrospective -- meaning that participants had been taking older birth control pills, which contained far more hormones than the ones most women use now. It is unknown what effect, if any, the lower-dose versions may have. Next, younger women, who are more likely to have a very low cardiovascular disease risk, are far more likely to choose this form of contraception. Older ones, who will potentially have a different heart health profile, are more likely to opt for sterilization.
"For young women who are nonsmokers and have a low baseline risk of cardiovascular disease, the excess vascular risk from oral contraceptives is likely to be small," said JoAnn E. Manson, MD, DrPH, chief of preventive medicine at Brigham and Women's Hospital and professor of medicine at Harvard Medical School in Boston.
In addition, these risk markers may not translate into actual morbidity and mortality. Oral contraceptives are associated with an increased risk of deep vein thrombosis, but several large epidemiological studies have not found actual boosts in cardiovascular disease.
"These are surrogate marker studies, but we have the epidemiological data to show that the attributable risk is minimal to none," said Mitchell Creinin, MD, director of gynecologic specialties at the University of Pittsburgh School of Medicine.
The risk of developing cervical cancer, however, appears to be real, albeit small, and disappears when this method of contraception is discontinued, according to a paper in the Nov. 10 Lancet.
"This increased risk begins to drop soon after women stop taking the pill and, after years, risk has returned to normal levels," said Dr. Jane Green, one of the Lancet study authors and a researcher at the Cancer Research UK epidemiology unit at the University of Oxford in England.
Researchers pooled 24 studies, including data on 16,573 women with cervical cancer and 35,509 without. They concluded that using the pill for five years increased the odds of developing this disease by 90% and translated to nearly one more case per thousand women taking the pill. This declined when use stopped, and, after a decade, the risk became comparable to someone who had never taken hormonal birth control.
The International Agency for Research on Cancer, part of the World Health Organization, classifies hormonal birth control as a cause of cervical cancer, and experts praised this paper for quantifying the magnitude of this risk. But they also cautioned that this information needed to be balanced with long-documented benefits, such as a decreased risk of ovarian cancer.
"Women should be informed about the different risks and benefits of taking something like oral contraceptives," said Debbie Saslow, PhD, director of breast and gynecologic cancer at the American Cancer Society. "There is a very slight increase in cervical cancer risk, but there are also benefits."
Experts also added that recommended Pap smear intervals should not change for women who use hormonal birth control.