- Hormonal birth control methods can impact your risk for certain cancers.
- The pill, patch, and ring are linked with a lower risk for ovarian, uterine, and colon cancers.
- A major study last year, however, found slightly increased breast cancer risk in women using hormonal birth control.
- It’s important to weigh that risk against birth control’s other health benefits.
When it comes to hormonal birth control in particular – including the pill, the ring, and some IUDs – there’s another element to consider: Its impact on cancer risk.
You may have already heard about the relationship between birth control and cancer, especially after a large study last linked hormonal contraceptives with an increased risk of breast cancer.
But that single study doesn’t tell the whole story. Although some birth control methods are associated with a higher risk for some cancers, they’re also associated with lower risk for other cancers.
It’s a relationship that gets pretty confusing pretty quickly, so INSIDER asked gynecologist Dr. Alyssa Dweck, author of “The Complete A to Z for your V,” to explain it all. Here are five things you should know.
1. The pill is linked with lower risks for three cancers
There’s consistent evidence to show that using the pill – specifically, the “combined” pill that contains both estrogen and progestin – is associated with a lower risk of ovarian, endometrial, and colorectal cancers, according to the US National Cancer Institute (NCI).
The pill’s protection against ovarian cancer – a disease that’s known for vague, hard-to-spot symptoms – is especially powerful.
Women who’ve ever used the pill have a 30% to 50% reduced risk of ovarian cancer compared to those who’ve never used it, the NCI website says. This protection increases the longer you use the pill, and it’s been found to continue up to 30 years after you stop taking it, Dweck explained.
“The risk reduction of the pill on ovarian cancer is so notable that we often recommend this to women who are genetically susceptible BRCA carriers,” she added. (BRCA gene mutations, as a refresher, increase the risk of both breast and ovarian cancer.)
Researchers have suggested that the pill reduces ovarian cancer risk because it reduces the number of times a woman ovulates in her lifetime. This helps prevent unintended pregnancy, of course, but it also reduces your exposure to naturally occurring female hormones, which in turn may protect against ovarian cancer, according to the NCI.
Risk of endometrial cancer is reduced by at least 30% in women who’ve used the pill, the NCI adds, and pill use is also associated with 15% to 20% reduced risk for colorectal cancer, which is currently on the rise among young people.
Finally, according to American College of Obstetricians and Gynecologists (ACOG) the patch and the ring – two other forms of birth control that use the same combination of hormones – can also decrease the risk for these cancers.
2. Cervical cancer risk, however, increases with the pill
Women who have used the pill for five or more years have a higher risk of cervical cancer than women who’ve never used it, according to the NCI. That risk increases the longer the pill is used and decreases over time once you stop taking it.
But it’s good to remember that the most important risk factor for cervical cancer is infection with human papillomavirus (HPV), the American Cancer Society explains. HPV is the most common sexually transmitted infection, according to the Centres for Disease Control and Prevention (CDC). Specific strains of the virus are responsible for almost all cervical cancers, the CDC notes, and you can be exposed to them whether or not you use the pill.
The good news is that a simple screening test called the Pap smear can catch worrisome changes in cervical cells before they become cancerous. Here’s a guide to when and how often you should be getting the test. Plus, there’s a vaccine that protects against the most dangerous HPV strains, and it’s currently approved for many people up to age 26.
3. A large study found a link between hormonal birth control and breast cancer
Older research had already found that using the pill was associated with a slightly higher risk of breast cancer, according to the NCI. But in late 2017, a new study reignited conversation around the topic.
The study concluded that using all hormonal birth control – including the pill and the hormonal IUDs – was linked with a higher risk of breast cancer. The finding prompted waves of media reports, but it’s important to know that both the overall risk and the increase in risk were small.
The study followed 1.8 million women for more than 10 years. In the group that didn’t use hormonal birth control, there were 55 cases of breast cancer per 100,000 women per year. In the group that did use hormonal birth control, there were 68 cases of breast cancer per 100,000 women per year. (The risk also increased the longer a woman used hormonal birth control.)
It’s worth noting, however, that the researchers said the study was limited because they weren’t able to take into account other factors that can influence breast cancer risk, like alcohol consumption and physical activity levels.
“The bottom line is that the overall risk is very low but increases with duration of use,” Dweck said.
And birth control choices aren’t the only thing that matter for your personal breast cancer risk.
“There are other risks factors for breast cancer, some of which women don’t necessarily pay as much attention to, like alcohol use, smoking, and obesity,” Dweck said.
4. People who have or had breast cancer should not use hormonal birth control
Things are different if you currently have or previously had breast cancer. Having a personal history of the disease means you shouldn’t use any hormonal contraception, according to the CDC’s medical eligibility criteria for birth control. That includes the combined pill, the progestin-only pill, the patch, the ring, the shot, the implant, and the four hormonal IUDs.
This, as Dweck explained, is because many breast cancer tumours are “hormonally sensitive,” meaning they have specific receptors for the female hormones estrogen and progesterone. Taking hormonal birth control, which contains synthetic versions of these hormones, could potentially cause tumours to grow or come back.
5. When choosing a birth control, weigh the benefits and the risks with a doctor
Every birth control method has pros and cons. They have different rates of effectiveness, different effects on your period, and different side effects and risks beyond their potential impact on cancer. All of those factors interface with your personal medical history, too.
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