Does the Pill Cause Cancer?

Ovarian, Colon, and Breast Cancer Risks From the Pill

In general, it appears that if you use the pill, there is no increase in your overall cancer risk. The pill may, in fact, actually have a protective effect against certain types of cancers. But it is understandable that you may be concerned that the pill causes cancer.

How come? The hormones of estrogen and progesterone, that naturally form in your body, have been found to effect the development and growth of some cancers. Birth control pills (as well as other forms of hormonal birth control) contain synthetic forms of these hormones. This has lead many people (as well as researchers) to wonder if there is any link between these widely used birth control methods and cancer risk. So let’s take a closer look at the question, does the pill cause cancer?

The Pill and Ovarian Cancer

The Pill and Cancer Risk
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What Is Ovarian Cancer?

Ovarian cancer is cancer that starts in the ovaries. It is the fifth most common cancer among women, and it causes more deaths than any other type of female reproductive cancer. It is estimated that approximately 30,000 new cases of ovarian cancer will be diagnosed each year, with 15,000 women dying from this disease.

Does the Pill Cause Ovarian Cancer?

The pill is a type of hormonal birth control. Combination hormonal birth control methods consist of a progestin and a synthetic estrogen. Some hormonal contraceptives can actually offer you the the extra benefit of reducing your ovarian cancer risk. Please keep in mind that the main reason to use hormonal birth control is for contraception (to prevent an unintended pregnancy)—you can consider these possible noncontraceptive benefits when determining which hormonal birth control method to choose.

The following is a list of specific hormonal prescription birth control methods that have been shown to be effective in lowering your risk of ovarian cancer:

  • The Pill: Research has shown that if you take the pill for 15 years or more, your ovarian cancer risk is reduced by 58 percent; 10-14 years of pill use lowers your risk by 44 percent; and 5-9 years of pill use cuts your risk by 36 percent. Even women who only used the pill for 1-4 years saw a benefit (reducing their ovarian cancer risk by 22 percent). 
It seems that this protective benefit may become weaker the longer it has been since you used the pill. But, this protective effect is still significant even 30 or more years after pill use stopped. Over the past 50 years, it is estimated that 200,000 cases of ovarian cancer and 100,000 deaths worldwide have been prevented by birth control pill use, and that if use remains at the current level, as many as 30,000 ovarian cancers could be prevented each year.
  • Low-Dose vs. Higher Dose Pills: Lower-dose birth control pills contain the lowest amount of estrogen (10-20 mcg) plus one of the eight types of progestin. Regular-dose pills contain 30–35 mcg estrogen plus progestin, and high-dose pills have around 50 mcg of estrogen plus progestin. The reduced risk of ovarian cancer in Pill users is thought to be caused because the hormones stop ovulation. Studies suggest that there does not appear to be a different level of ovarian cancer risk reduction from different estrogen doses in the pill. The protective effect (against ovarian cancer risk) has been shown to take place with low-dose pills as well as regular and high-dose ones.
 Some researchers also suggest that the progestin levels in the pill might be as important as ovulation suppression in the prevention of ovarian cancer.

    After comparing birth control pills by both estrogen and progestin potency, research shows that pills with higher levels of progestin were associated with greater reduction in ovarian cancer risk than those with lower progestin potency (regardless of the amount of estrogen). It seems that women who took pills with higher progestin levels show a significant reduction in ovarian cancer risk, even when taken for a short amount of time (3-18 months). The amount of estrogen in the pill did not seem to affect ovarian cancer risk.

  • Depo Provera: The progestin-only Depo Provera injection also shows a similar protective effect on your ovarian cancer risk. This is most likely due to how the progestin may suppress ovulation.
  • NuvaRing and The Patch: Given that both of these birth control methods contain a combination of progestin and estrogen, it is believed that they should offer you the same protective benefit from ovarian cancer as combination birth control pills do. The research on this, however, is limited.

The Pill and Colon Cancer

The Pill and Colon Cancer
Does the Pill Cause Colon Cancer?. Sebastian Kaulitzki/Getty Images

What Is Colon Cancer?

Colon cancer (or colorectal cancer) is cancer that starts in the large intestine (colon) or the rectum (end of the colon). According to the American Cancer Society, colorectal cancer is one of the leading causes of cancer-related deaths in the United States and is the fourth most common cancer in men and women.

Does the Pill Cause Colon Cancer?

The answer to this question is also no. Research suggests that hormonal contraceptives (like the pill) may also have the added benefit of reducing your risk of colon cancer (although the data is limited and more research is needed). The following is a list of hormonal birth control methods that seem to be effective in lowering your risk of colon cancer:

  • Combination Birth Control Pills: A meta-analysis of 20 studies investigating the relationship between the risk of colon cancer and combination birth control pill use revealed that there is an 18 percent reduction in the risk of developing colon cancer among those women who use the pill. This protective effect was greatest for recent pill use and showed no duration effect (meaning, it does not matter how long you had been using the pill). Other studies also suggest that if you are currently or recently using combination birth control pills, you are more likely to have a lower risk for colon cancer. Past use of combined pills does not appear to result in a reduction of colon cancer risk.
The reduced risk of colon cancer in Pill users is thought to be due to a few reasons.

    Bile acids are made by the liver and work with bile to break down fats. Continuous exposure to bile acids can be carcinogenic on the tissues in the colon, thereby causing colon cancer. The estrogen and progestin in the pill may reduce the secretion of bile acids.
 Another cause of colon cancer may be due to mutated or damaged repair genes. Microsatellite instability is a condition where a cell has difficulty repairing DNA because it is damaged. About 90 percent of tumors in people who have certain types of colon cancer show microsatellite instability. Research suggests that the combination of estrogen and progestin has been related to a decrease in microsatellite instability.

  • Low-Dose vs. Higher Dose Pills: There does not appear to be a lot of information on the type of pill formulation and the lowered risk of colon cancer. Research seems to indicate that colon cancer risk reduction is the same—so the amount of estrogen or progestin in the pill does not matter. The protective effect against colon cancer risk has been seen in studies ranging from the 1960s (when mostly high dose pills were in use) to 2008 (when newer pill formulations with lower hormone levels were more typically used).
  • NuvaRing and the Patch: Given that both of these birth control methods contain a combination of progestin and estrogen, it is believed that they should offer the same protective benefit from colon cancer as combination birth control pills do. Research, though, is limited.

The Pill and Breast Cancer

The Pill and Breast Cancer
Does the Pill Cause Breast Cancer?. Echo/Getty Images

What Is Breast Cancer?

Breast cancer starts when cells in the breast begin to grow out of control. These cells usually form a tumor that can often be seen on an x-ray or felt as a lump. Most breast cancers begin in the ducts that carry milk to the nipple. Breast cancer is the most common cancer among American women (except for skin cancers). About 1 in 8 women in the US will develop invasive breast cancer during their lifetime.

Does the Pill Cause Breast Cancer?

The available research on this topic is mixed. The conflicting results may be due to the fact that the hormone levels in the birth control pills have changed over the years. Early birth control pills contained much higher levels of hormones than today's low-dose pills and posed a higher breast cancer risk. There are concerns that the pill may cause breast cancer because the hormones in birth control pills may overstimulate breast cells—this may increase your risk of breast cancer. There is greater concern if you’re at high risk for breast cancer due to:

  • A strong family history of breast cancer
  • Past breast biopsies showing abnormal cells
  • You or a family member has an abnormal breast cancer gene

Research on this topic varies. In general, most studies have not found an overall increased risk of breast cancer due to the use of the pill. That being said, several research studies have suggested that using the pill may increase your risk of having breast cancer. Here is a quick review of some of the research on this topic:

  • Duration of Pill Use: Studies that suggest a link between pill use and breast cancer usually show that you may have a slightly higher risk of breast cancer while using the birth control pill. Past use of the pill does not appear to be linked to breast cancer risk. But current use slightly increases your risk. One study suggested that current or past use of birth control pills did not increase the risk of breast cancer in women aged 35 to 64. But the researchers did point out a small increase in risk among women aged 35 to 44 who used birth control pills and had a family history of breast cancer.
  • Type of Pill: It seems that using birth control pills that contain a higher dose of estrogen may be linked to a higher risk of breast cancer, but using birth control pills with a low dose of estrogen (the type of birth control pills that many women take) is not linked to a higher risk of breast cancer. Some studies note that the increased risk of breast cancer associated with pill use occurs mainly in women who are using triphasic pills. High-dose estrogen birth control pills could possibly double the risk of breast cancer.

The Bottom Line: Many of these studies refer to the relative risk of having breast cancer. An increase in relative risk must be multiplied by your absolute risk to figure out your real risk. Most experts agree that an average woman (younger than 50) with no family history of breast cancer and no abnormal breast cancer genes has an absolute risk of breast cancer that is less than 2 percent. So if that risk doubled, it would still be less than 4 percent. Thus, for most women, especially young women, medical professionals suggest that the benefits of birth control pills far outweigh the risk.

Sources:

Beaber EF, Buist DSM, Barlow WE, Malone KE, Reed SD, Li CI. "Recent oral contraceptive use by formulation and breast cancer risk among women 20 to 49 years of age." Cancer Research. 2014;74(15):4078–4089.

Bosetti C, Bravi F, Negri E, La Vecchia C. "Oral contraceptives and colorectal cancer risk: A systematic review and meta-analysis." Human Reproduction Update. 2009;15(5):489–498.

Collaborative Group on Epidemiological Studies of Ovarian Cancer. "Ovarian cancer and oral contraceptives: Collaborative reanalysis of data from 45 epidemiological studies including 23 257 women with ovarian cancer and 87 303 controls." The Lancet  2008;371(9609):303–314. 

Ness R, Grisso J, Klapper J, et al. "Risk of ovarian cancer in relation to estrogen and progestin dose and use characteristics of oral contraceptives. SHARE study group. Steroid hormones and reproductions." American Journal of Epidemiology. 2000;152(3):233–41. 

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