What you should know about birth control and breast cancer


A lot of intimidating headlines have recently declared that taking hormonal birth control raises your risk of breast cancer. Some cited a specific number—38 percent—while others left it as a vague threat. Given that about a quarter of all women in the U.S. use some kind of hormonal birth control, this sounds like a huge public health issue.

Here’s the reality: the very slight increased risk of breast cancer is actually something we’ve known about for a long time. We also know that hormonal contraception can protect you against other types of cancer, and that there are lifestyle factors that can play an equally large (if not larger) role in determining your breast cancer risk. And for plenty of women, hormones are still the right choice.

Let’s break this down.

Only one aspect of these findings is new, and even that isn’t all that surprising

Previous studies on how birth control affects cancer risk focused mainly on the pill. It takes time to determine whether people who start taking birth control in their 20s see changes in risk later, because you have to follow that population for decades. Intrauterine devices (IUDs) and hormonal implants simply weren’t that popular a few decades ago, whereas the pill was widely used.

This new study, which came out in the New England Journal of Medicine, is one of the first to look at how the hormones in non-oral forms of birth control and modern pill formulations affect cancer risk. That’s a crucial question to ask, especially since an increasing number of people are looking at IUDs as a long-term, highly-effective way to prevent pregnancy.

Mia Gaudet, Strategic Director of Breast and Gynecologic Cancer Research at the American Cancer Society, noted that there was some hope that modern pills, with lower hormonal doses, would minimize the added breast cancer risk, which this NEJM study failed to show. But she also confirmed that these new findings are in line with previous work.

“It’s not shocking to me that a low dose combination pill over a long period of time would increase breast cancer risk,” says Larry Norton, the Scientific Director of the Breast Cancer Research Foundation. He explains that it doesn’t take a very high dose to increase your overall estrogen or progesterone exposure, because people who use contraceptives tend to do so for many years. Even a small amount in each pill adds up over decades, and generally speaking, the longer someone is exposed to female sex hormones (i.e. estrogen and progesterone), the greater their risk of breast cancer. Getting your period early (especially before age 12), and going through menopause late are both linked to a higher risk, and researchers think that’s because these individuals are simply exposed to their own hormones for longer. Any kind of drug that increases your hormone levels could be expected to raise your risk of breast cancer.

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Closeup still life of Zorane tablets, a series of low-estrogen birth control pills. Shown are three packs, one open, two closed. (Photo by Hulton Archive/Getty Images)
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This is also why it’s unsurprising to Norton that other kinds of hormonal contraception increase the risk of breast cancer as well. We didn’t previously know for sure that implants and IUDs would release hormones into the bloodstream, but it’s not shocking to him that they do. And since they increase your hormonal exposure, they’ll also increase your breast cancer risk.

That may change how some physicians counsel their patients, though. “I typically had a bias that a progesterone-acting IUD was acting locally, and so wasn’t going to affect breast cancer risk at all,” says Rachel Jankowitz, an oncologist at UPMC Hillman Cancer Center. She explains that while she knew some progesterone might get into the bloodstream, she assumed it wouldn’t be enough to impact cancer risk. “This does change the language we need to use when talking to patients about birth control options.”

This study tested some new formulations of the pill for the first time, but again, the fact that they found a risk is consistent with what we already knew.

It’s a very small increased risk, and it comes along with some protective benefits

According to this recent study, there would be about 13 extra breast cancers each year for every 100,000 patients on birth control, or a difference of 68 versus 55 cases per year.

Population statistics like this are tricky, because 13 additional cases is a very small number when compared to the many thousands who already get cancer diagnoses every year. But of course, for those 13 hypothetical people, the impact is massive. Everyone is worried that they’ll be one of the unlucky few, but statistics mean nothing to the individual. We can say with certainty that across an entire population, there’s an increased risk of about 20 percent. But we can’t say what any one person’s risk is. In other words, this does not mean you are 20 percent more likely to get breast cancer. And on top of that, breast cancer isn’t the only concern.

Setting aside the menstrual symptoms and painful conditions that the pill can help with, they also “have a net cancer benefit, as they reduce the risk of ovarian, endometrial, and colorectal cancers,” said Mia Gaudet.

This is precisely why medical decisions have to be made personally. You have to weigh the risks and benefits and figure out whether it’s worth it. Even a small increased risk may be too much for you to feel comfortable, especially if you know from family history or a genetic screening that your risk is already quite high. Or, you may be reassured by the fact that hormonal birth control reduces the risk for endometrial and ovarian cancers. The point is, the question of whether or not hormonal birth control is worth it is up to you—so you’ve got to make sure you’re well informed.

Jankowitz notes that your decision will also depend on your age and how long you might be taking contraceptives. Older people who are already at an elevated risk for breast cancer may want to avoid even small additional risks. Being young and at extremely low risk of cancer shifts the equation a bit. “For the average woman in her 20s or 30s, probably this minimal elevation is outweighed by their need for contraception,” she says. “And an unwanted pregnancy is not a good thing.”

The recent findings didn’t control for two of the biggest lifestyle factors that influence breast cancer risk

There’s a whole host of factors that make you more likely to get breast cancer that you can’t change, but the two biggest ones that you can change are drinking alcohol and being overweight.

Obesity increases your risk for the same reason that birth control does: more hormone exposure. Fat cells produce estrogen, especially after menopause, so more fat means more estrogen. Not being physically active also increases your risk, perhaps even more so than weight itself.

It’s not quite clear how alcohol increases breast cancer risk, but the more you drink, the more you raise your risk. The effect isn’t limited to breast cancer—you’re at a higher risk for many other types of cancer if you drink, especially if you have 2-3 drinks a day. Some researchers think a recent uptick in cases of colorectal cancer in young people might be due to increased alcohol consumption.

The recent NEJM study didn’t take physical activity or alcohol consumption into account, which they noted as a limitation to their results. Of course, based on prior studies, we wouldn’t expect the increased risk to disappear after controlling for these factors, but we might expect it to decrease.

For lots of people, these findings change nothing

People take birth control for a wide variety of reasons, just one of which is preventing pregnancy. Some take it to control acne or to lessen PMS symptoms. Some just want to know when they’re going to get their period. Some have illnesses that are much easier to control on hormonal birth control.

Any or all of these might be reason enough to stay on hormones, especially when there’s really only one long-term option that doesn’t increase your breast cancer risk. That option, a copper IUD, comes with its own potential problems. For one, it can cause heavy periods and intense cramping, which many people are actively trying to get rid of when they start taking contraception. For another, controlling your menstrual cycle—whether it be the emotional side effects or the frequency of your periods—is a massive boon. Bleeding for several days every single month is inconvenient to say the least, so being able to predict when the bleeding will commence can be a hugely attractive part of the pill. And having a cervix unstretched by childbirth increases the likelihood that IUD insertion will be painful, or that the IUD will fall out. For some patients an IUD is a set-it-and-forget-it contraceptive miracle, while for others the hardware is a real headache. But if going hormone-free sounds like the best option to you, the copper IUD might be the way to go.

Concerned about hormones might make some people turn to family planning apps. These apps try to help you time when you have sex, such that that you avoid your ovulation period. The method isn’t entirely ineffective, and if you have religious beliefs that caution against contraception, it can certainly better than condoms on their own (and it’s a lot better than nothing). But the reality is that no app can tell you for sure when you’re ovulating or not, and it only takes being off by a day to get you pregnant.

An official statement from the American Congress of Obstetricians and Gynecologists noted that some need birth control because pregnancy itself would be a danger, and for these patients the small increase in breast cancer risk would be well worth it. ACOG also highlighted that “for many women, hormonal contraception—the pill, the patch, the ring, IUDs, and the implant—is among the most safe, effective and accessible options available.”

Too many people seem to be uninformed about a drug they take every day

Perhaps the biggest issue here isn’t how novel these results are or what small bit of new information we gleaned, but the fact that many seem surprised to find out what doctors have known for literal decades. About 10 million people rely on oral contraception, and each and every one of them should have been informed about the risks they were taking on when they opted to take the pill. That’s not to say that the added risk should have dissuaded them, but just that they should have been allowed to make a truly informed decision.

If you are one of the many people for whom going off hormonal birth control would be a burden, try not to feel scared by this new study. The increased risk you take on is small, and you may be far better off trying to minimize your risk by staying physically active and limiting your alcohol intake. If you are still worried, talk to a medical professional before you make any decisions. Your gynecologist should be able to walk you through the available options and should listen to how you feel about birth control.

If your wishes and concerns aren’t being met with understanding, you should try to find another doctor who will actually listen to you. This isn’t always possible, especially if you have limited insurance and finances, but it’s worth at least trying to find someone who will help you make the best possible decision. And if circumstances make you feel locked into taking hormonal contraception, rest assured that you’re increased risk may not be zero, but it’s also very small. You could be the healthiest person in the world and still get cancer. But you can help reduce your risk in other ways. Get to the gym, eat a balanced diet in order to maintain a healthy weight, and don’t drink excessively—and enjoy the freedom that birth control offers you.

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