Do Birth Control Pills Cause Breast Cancer? The Latest Study

Last month, you might have seen headlines warning you that hormonal birth control increases risk for breast cancer. This news came from a study that examined the medical records of nearly 1.8 million Danish women — and the huge sample size lent heft to the findings, several of which stood in stark contradiction to commonly held beliefs about modern hormonal contraception.

Some types of hormonal contraception could increase breast cancer risk, while others may not. But the Pill also reduces risk for endometrial and ovarian cancers.

Birth control comes in two “flavors” — hormonal and nonhormonal. Hormonal contraception is among the most effective, and includes birth control pills, hormonal IUDs, the shot, the vaginal ring, the implant, and the patch. Nonhormonal contraception ranges from very effective, including surgical sterilization and the copper IUD, to the not-quite-as-effective, including condoms, diaphragms, and withdrawal. (With the exception of condoms, birth control does not provide protection against STDs.)

Hormonal contraception is one of the greatest achievements in the history of medicine, and offers those wishing to control their fertility an array of effective options. However, as with all effective medications, there is potential for side effects. And, because many forms of hormonal birth control contain types of estrogen, and exposure to estrogen is a risk factor for breast cancer, many people wonder if hormonal birth control might increase users’ chances of developing breast cancer later in life.

Most birth control pills contain a combination of two hormones: estrogen and progestin (synthetic progesterone). Other hormonal methods, such as the ring and the patch, also use combinations of these two hormones.

There are also pills that don’t contain estrogen, called POPs, or progestin-only pills — aka the “minipill.” Additionally, hormonal IUDs, the implant, and the shot are progestin-only methods.

What Previous Studies Have Shown

The connection between hormonal contraception and breast cancer is murky, because the association is difficult to study properly. There are so many different types of hormonal contraceptives, each with different dosages, different chemical formulations, and different ways of entering the body. We can’t tease these differences apart on the one hand, but make blanket statements about hormonal contraception as a whole on the other hand. But we can look at the available evidence and see where it points. Continue reading