The most popular method of birth control in the United States is the Pill, followed by tubal ligation (permanent sterilization, or getting your tubes tied) and condoms. The Pill is a hormonal method of contraception, while sterilization and condoms are nonhormonal. The distinction between hormonal and nonhormonal methods of birth control are simply that the former contain synthetic versions of human hormones, while the latter do not.
By suppressing ovulation and thinning the uterine lining, the Pill can reduce risk of ovarian and endometrial cancers.
Glands in our bodies, called endocrine glands, produce hormones; additionally, testes and ovaries — which are parts of the human reproductive system — manufacture hormones. Human hormones are powerful chemicals, which do all sorts of jobs, from triggering puberty to helping us extract energy from the foods we eat. So it’s not a huge stretch to wonder if exposure to the hormones present in certain birth control methods — such as the Pill, in addition to the patch, the ring, the shot, the implant, and some types of IUDs — might have unintended effects on the body. Because hormones can play a role in cancer — either in protecting against it or aiding in its development — researchers are very interested to know if the Pill might increase or decrease risk for various types of cancer.
It’s actually a bit tricky to investigate the possible associations between the Pill and various types of cancer. First of all, there are dozens of types of birth control pills, all with different versions of synthetic hormones, at different dosages, and in different proportions to one another. Furthermore, the types of oral contraceptives on the market change over time — today’s birth control pill is not your mother’s birth control pill. Studying “the Pill” as a single entity could obscure differences between brands. Secondly, most cancers tend to develop later in life, many years after someone may have taken oral contraceptives. Researchers need to be careful to control for all the variables that might increase or decrease cancer risk. Continue reading