One would think that modern advances have made birth control safer. A new study says that’s not the case.
If you are one of the nearly 25% of American women who use oral contraceptives, IUDs, or other birth control implants, you might have assumed that today’s medication was safer than those of years past. After all, modern contraceptives now contain lower doses of hormones. A new study has warned that women who use hormonal contraceptives are at increased risk for breast cancer.
A Danish study published earlier this month in the New England Journal of Medicine that followed 1.8 million women for more than ten years found that women taking hormonal birth control are at higher risk for breast cancer than those who are not on hormonal birth control. More, the risk increased with age and extended length of use.
Birth control pills suppress ovulation by altering the hormones estrogen and progesterone. An IUD thickens the mucus that lives on the cervix, thus blocking and trapping the sperm. In some instances, an IUD also suppresses ovulation. While estrogen and progesterone occur naturally in the body, they both play a role in the development and growth of breast cancer.
The primary finding of the study was that women who were currently using hormonal contraceptives, or who had used them recently, had a 20 percent higher risk of breast cancer than those who did not. That means, according to the New York Times, for every 100,000 women, hormonal contraceptive use causes an additional 13 cases of breast cancer a year.
“We did actually expect we would find a smaller increase in risk because today we have lower doses of estrogen in the hormone contraceptives, so it was surprising that we found this association,” said Lina S. Mørch, the paper’s lead author.
The study found very few differences between the types of contraceptive use, meaning that both birth control pills and IUDs posed risks. Even those women who use progestin-only IUDs had a higher risk for breast cancer than those who had never used hormonal contraceptives, to the tune of 21 percent. This finding surprised the researchers.
Although the relative risks remain small, the authors note that the risk increases with age and exposure. Women who continued on hormonal birth control for over ten years experienced a 38 percent increase in breast cancer compared to those who never used birth control.
Scientists and health care providers are responding swiftly to the study, many stating that they are unsurprised by the results. The study findings mimic previous study results showing that drugs that alter hormone levels can increase the risk of cancer.
Researchers are also quick to point out that hormonal birth control comes with benefits, such as prevented pregnancies, more comfortable periods, and a reduced risk of other types of cancer such as ovarian, endometrial, and colorectal cancer.
“Nothing is risk-free, and hormonal contraceptives are not an exception to that rule,” said Dr. Øjvind Lidegaard, the paper’s senior author. Women should individually weigh the risks and benefits with their healthcare providers.