Do birth control pills cause cancer?

Do birth control pills cause cancer?
The science is still evolving as to if or how much hormonal birth control increases the risk for developing cancer.

About 65 percent of American women use some form of birth control, according to the U.S. Centers for Disease Control and Prevention. And birth control pills are used by about 25 percent of women aged 15 to 44.

But for years, the important question was whether using birth control pills causes cancer.

The latest research published in March 2023, concludes that progestogen-only contraceptives may increase the risk of breast cancer by 20 percent to 30 percent for those currently or recently taking this form of birth control. This proved to be the same as taking a combination estrogen and progestagen contraceptive.

This latest finding contradicts an earlier study from 2017 that showed single hormone birth control containing only progestogen did not elevate breast cancer risk.

The science is still evolving as to how much hormonal birth control — taken daily as an oral contraceptive pill or injected or implanted — increases the risk for developing cancer. Most studies have been observational (where researchers merely observe the effect of a particular risk factor over time) rather than randomized controlled clinical trials, considered the scientific gold standard because it tracks two groups of individuals (those who receive a particular drug or medication and those who don’t).

“That’s going to be hard to do for birth control pills, because you can't always find people who are willing to be randomized to take birth control pills or not take them,” says Dr. Rachel Urrutia, an associate professor of obstetrics and gynecology at the University of North Carolina School of Medicine, in a news report on the newest study.

Still, observational studies over the years have produced some consistent findings linking hormonal birth control with cancer — both elevating risks for certain cancers and reducing risks for others.

Other variables like genetics and lifestyle behaviors also complicate isolating the cause and effect of hormonal contraception and cancer. Each individual is unique, so speaking with your healthcare team is essential to determining your personal risks.

To help understand what is known, this article will examine:

If you’ve been diagnosed with cancer and want to get a second opinion about your diagnosis or treatment options,call us or chat online with a member of our team.

What is hormonal birth control?

The most common type of oral contraceptive used in the United States contains synthetic versions of the female hormones estrogen and progesterone, and often is referred to as a “combined pill.” The “mini-pill” is another type of hormonal birth control pill that only contains progestin, a synthetic type of progesterone. Taken by mouth each day, these pills prevent ovulation and change the lining of the uterus and cervical mucus to prevent sperm from fertilizing an egg during intercourse.

In addition to the pill, other types of hormonal contraceptives that may contain a combination of estrogen and progesterone or just progestin include:

  • An injection given once every three months under the brand name Depo Provera
  • Intrauterine devices or IUDs that release hormones when placed in the uterus
  • Trans-dermal patches placed on the arm, back, buttocks or belly that release the hormones through the skin
  • The vaginal ring, which releases the hormones when placed in the vagina

Because naturally occurring hormones like estrogen and progesterone may promote  growth of certain forms of cancer like breast cancer, which has receptors for these hormones, researchers are studying how synthetic versions of the hormones, like those in hormonal birth control, may affect cancer risks.

Should you worry about using hormonal birth control?

Research shows that using hormonal birth control does impact cancer risks, and the type of hormones taken — whether estrogen and progesterone or progestin alone — may make a difference.

Observational studies have shown that woman who take combined hormonal contraception have a slightly increased risk of developing breast cancer and cervical cancer, when compared to those who do not take hormonal birth control. While most studies have examined the combined hormones, a mounting body of research on the progestin only or “mini-pill” has shown similar risks for breast and cervical cancers.

But these risks may be transitory since the findings have consistently shown that once women stop taking the hormonal contraception their risk returns to normal after an estimated 10 years. The average woman not taking hormonal birth control has a one-in-eight chance of having breast cancer in her lifetime, so when taking the pill, and for up to a decade after stopping, that risk is slightly elevated. But keep in mind, cancer risk generally also increases with age, which makes assessing the link between birth control and cancer more complicated.

Research also has revealed that taking hormonal birth control may actually reduce the risk of endometrial, ovarian and colorectal cancers.

For uterine cancer, of which endometrial cancer is the most common type, a 2018 study in the journal JAMA Oncology found taking the pill reduced the risk for uterine cancer by 34 percent.

Studies like one published in the American Journal of Epidemiology in 2000 found that woman taking hormonal birth control reduced their risk of developing ovarian cancer by as much as 40 percent, compared to those who had never taken hormonal contraceptives. 

What are the cancer risks beyond hormonal birth control?

When weighing the risks of hormonal birth control, many other factors may come into play like family history of cancer, genetic mutations, lifestyle, current health conditions and reproductive plans. That is why it’s important to discuss the pros and cons unique to you with your doctor.

For instance, researchers found hormonal birth control helped reduce the risk for those with a family history of ovarian cancer or genetic mutations like BRCA1 and BRCA2 that are linked to an increased risk for developing ovarian cancer.

Lifestyle factors — including eating a healthy diet, maintaining a healthy weight, exercising regularly, not using tobacco and limiting alcohol consumption — are also important to mitigating cancer risk overall.

While research has shown taking hormonal birth control for five years or more may increase risks of cervical cancer, regular pap smears to screen for human papilloma virus (HPV) may significantly offset the risk.

Generally, women taking hormonal birth control should be routinely screened for cancer “as per general population risk assessment guidelines,” says Ruchi Garg, MD, Chair, Gynecologic Oncology at City of Hope® Cancer Center City of Hope Atlanta, Chicago and Phoenix.

What are the options for non-hormonal birth control?

If, in consultation with your doctor, you decide hormonal birth control is not right for you, non-hormonal options are available. Effectiveness varies, so again, be sure to consult with your healthcare team to ensure the method you select meets your reproductive goals.

Non-hormonal birth control includes:

  • A non-hormonal intrauterine device (IUD)
  • A diaphragm
  • A cervical cap
  • Condoms
  • Spermicides
  • Sterilization — either a tubal ligation for a woman or a vasectomy for a man.

When deciding on the birth control method that may be right for you, considerations include your reproductive plans, lifestyle, medical history, current health conditions and genetics. A health care professional may help sort through the research and the options that are best for you.

If you’ve been diagnosed with cancer and want to get a second opinion about your diagnosis or treatment options, call us or chat online with a member of our team.