Do Oral Contraceptives Cause Cancer?

Oral contraceptives, or birth control pills, are hormone-containing medications taken to prevent pregnancy. Birth control pills are formulated using one, or both, of the following hormones: estrogen and progestin.

• combination birth control pills contain both estrogen and progestin
• progestin-only birth control pills, or “mini pills,” contain only progestin

In addition to preventing pregnancy, birth control pills have a variety of other health benefits, such as reducing period pain, preventing ovarian cysts, regulating menstrual cycle, and more. However, as with any medication, birth control pills do come with a variety of side effects and risks.

So, does birth control cause cancer? Current research shows that there’s a dual relationship between oral contraceptives and cancer, as we explain below.

Here’s what research has told us about the relationship between oral contraceptives and certain cancers.

Breast cancer

In one early analysis, researchers reviewed results from roughly 54 studies on breast cancer and oral contraceptives. Study results found multiple relationships between the pill and breast cancer.

For women taking combination birth control, the risk of being diagnosed with breast cancer was slightly higher, both during and up to 10 years after stopping the pill. However, cancer diagnoses in women who had taken birth control pills were less clinically advanced than those who had never taken the pill.

In a more recent review from 2010, researchers found that currently taking oral contraceptives was associated with a slight increase in the risk of developing breast cancer. However, they also found that a history of birth control pill use was not associated with increased risk.

Cervical cancer

In a large analysis, researchers reviewed the data for over 52,000 women on the link between oral contraceptives and cervical cancer risk. Analysis of the literature showed that current oral contraceptive use was associated with an increased risk of invasive cervical cancer.

In addition, this risk was found to increase over time, with a higher risk being found in those who had been taking the pill for 5 years. Fortunately, cervical cancer risk declined after stopping the pill — and after 10 years of non-use, this increased risk was non-existent.

A recent systematic review and meta-analysis of 19 studies supports these results, suggesting that oral contraceptive use is associated with a higher risk of cervical cancer.

Endometrial cancer

In a more recent analysis on the connection between oral contraceptives and endometrial cancer, 36 epidemiological studies were reviewed. Unlike breast and cervical cancer, these studies found that birth control was associated with a decreased risk of endometrial cancer.

Interestingly, longer duration of birth control use was found to have a greater reduction in endometrial cancer risk. This risk reduction was also found to continue for more than 30 years after stopping the pill.

A previous systematic review supports these results. In this review, all studies found that birth control demonstrated some sort of protective effect from endometrial cancer.

Ovarian cancer

An early analysis of 45 studies investigated the link between oral contraceptive use and ovarian cancer risk. According to the results of the analysis, oral contraceptives demonstrated a protective effect against ovarian cancer.

Like endometrial cancer, this reduced risk was greater the longer someone took birth control. This protective effect continued for up to 30 years after stopping the pill.

A more recent meta-analysis from 2013 further investigated the link between oral contraceptives and ovarian cancer in women with the BRCA1/2 mutation. Analysis of 14 total studies indicated protective benefits from birth control on ovarian cancer risk, even in people with these mutations.

Colorectal cancer

In a meta-analysis from 2015, researchers analyzed a total of 29 studies that included 15,790 cases of colorectal cancer. Results indicated that previous use of birth control was associated with a reduced risk of colorectal cancer.

Like previous studies mentioned above, a greater reduction in risk was observed for those who took the pill for longer periods of time. In particular, the greatest risk reduction was seen after taking the pill for 42 months.

Another analysis of the Women’s Health Initiative Observational Study observed similar protective benefits of oral contraceptives. This study found that current and previous users of birth control had a lower risk of developing colorectal cancer than those who had never used birth control before.

Liver cancer

While multiple early studies suggested a potential correlation between liver cancer risk and birth control, results were conflicting. However, one meta-analysis from 2015 found no significant link between birth control pills and liver cancer. Any studies demonstrating a potential link were found to be statistically insignificant.

Research has shown that hormones can influence cancer risk because they change the way that cells divide and differentiate. For example, in breast tissue, both estrogen and progestin have been shown to increase cell division. This may explain why breast cancer risk is increased with combined oral contraceptive use.

However, in the endometrium, estrogen seems to increase cell division while progestin has the opposite effect. This explains why the combination birth control pill has a protective effect on certain cancers like endometrial cancer. This may also explain why progestin-only birth control options, such as the mini pill or the shot, carry less risk.

Ultimately, there are many factors that can influence cancer risk outside of hormones, including other carcinogens, viruses, lifestyle habits, and more.

If you’re concerned about your risk of cancer from taking birth control, talk with your doctor. They can review your medical and family history to help you determine which form of birth control is safest for you.

Alternately, you may choose to consider other non-hormonal birth control options, such as:

• Male or female condoms. Condoms are a safe, inexpensive way to prevent pregnancy when used correctly. While male condoms are more common, female condoms, or internal condoms, are also an option. Male and female condoms are anywhere from 79 to 97 percent effective at preventing pregnancy.
• Fertility awareness method. Fertility awareness involves no hormones, instead relying entirely on tracking your menstrual cycle. With this method, you track your temperature, cervical mucus, and other symptoms to determine when you should avoid intimacy. Fertility awareness is roughly 76 to 88 percent effective at preventing pregnancy.
• Diaphragm, cervical cap, or sponge. Diaphragms, cervical caps, and sponges were all popular birth control methods before the introduction of the pill. However, all three methods require the use of spermicide, which can cause irritation in some people. Diaphragms are up to 96 percent effective, followed by the sponge (91 percent) and the cap (86 percent).
• Non-hormonal IUD. Copper IUDs are the only non-hormonal option IUD option. Unlike the implant or hormonal IUD, the copper IUD provides pregnancy protection without the use of progestin. Copper IUDs offer the best non-hormonal protection at roughly 99.9 percent effectiveness.

Oral contraceptives are one of the most effective birth control methods on the market, and they have a handful of other positive health benefits. However, research suggests that oral contraceptives may cause a slight increase in breast and cervical cancer risk.

But research also suggests that birth control pills can decrease the risk of endometrial, ovarian, and colorectal cancer.

If you’re concerned about the risks of birth control, talk to your doctor. They can help you determine whether the benefits outweigh the risks, or whether there are better options for you to consider.