Women who take the pill may enjoy long-term health benefits well beyond preventing pregnancy. A new study suggests that using oral contraceptives protects women from certain cancers for at least 30 years.
Researchers at the University of Aberdeen in Scotland found pill users were less likely than other women to develop colorectal, endometrial, and ovarian cancers. About one in three women taking the pill were protected from developing ovarian and endometrial cancers, the study found. For colorectal cancer, about one in five cases were avoided.
It wasn't all good news. There was an increased risk of breast and cervical cancer in women who were currently or had recently been taking oral contraception, but that risk disappeared within 5 years of stopping the pill. And there was no evidence of a greater risk of these cancers appearing later in life.
Study author Lisa Iverson, Ph.D., and colleagues concluded that using the pill doesn’t appear to expose women to long-term cancer risks, and it may reduce the risk of some cancers long after users have stopped taking the pill.
Iverson is a research fellow in epidemiology at Aberdeen’s Institute of Applied Health Sciences.
The findings come from the Royal College of General Practitioners’ Oral Contraception Study, the world’s longest-running study of the health effects of the pill. The new results are based on 46,000 women who were followed for up to 44 years.
When the pill was first introduced in the United States in 1960, people worried about its potential long-term consequences, especially cancer, the research team noted.
Naturally occurring estrogen and progesterone have been found to influence the development and growth of some cancers, according to the National Cancer Institute.
Most oral contraceptives combine man-made versions of those female hormones.
Today, the pill is the contraception of choice for about 16% of reproductive-age women in the United States, according to the U.S. Centers for Disease Control and Prevention, and overall 100-150 million women around the world take it.
Research on the association between birth control pills and cancer risk has been mixed.
Encouragingly, though, this new study revealed no evidence of new cancer risks popping up later in life among women who had ever used oral contraceptives.
“These results provide strong evidence that most women do not expose themselves to long-term cancer harm if they choose to use oral contraception; indeed, many are likely to be protected,” the authors wrote.
The study was published in the American Journal of Obstetrics & Gynecology.