Do Oral Contraceptives Cause Cancer?

口服避孕药and cancer: A dual relationship

口服避孕药, 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 otherhealth 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副作用和风险.

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

What the research says about oral contraceptives and certain cancers

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

乳腺癌

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 审查 从2010年开始，研究人员发现目前服用口服避孕药与患乳腺癌患风险的略有增加有关。但是，他们还发现，使用避孕药的史与风险增加无关。

Cervical cancer

In a large analysis ，研究人员审查了52,000多名妇女在口服避孕药和宫颈癌风险之间的联系的数据。对文献的分析表明，当前的口服避孕药使用与浸润性宫颈癌的风险增加有关。

此外,这种风险被发现增加了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 系统评价 and meta-analysis of 19 studies supports these results, suggesting that oral contraceptive use is associated with a higher risk of cervical cancer.

子宫内膜癌

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.

有趣的是，发现较长的节育持续时间被发现降低了子宫内膜癌的风险。停止药丸后，还发现这种降低风险持续了30多年。

A previous 系统评价 支持这些结果。在这篇综述中，所有研究发现，节育症表现出子宫内膜癌的某种保护作用。

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 荟萃分析 from 2013 further investigated the link between oral contraceptives and ovarian cancer in women with theBRCA1/2 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 荟萃分析 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.

像上面提到的先前研究一样，对于那些长时间服用药丸的人，观察到了更大的风险降低。特别是，服用42个月的药后，出现了最大的降低风险。

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 荟萃分析 从2015年起，避孕药和肝癌之间没有显着联系。任何证明潜在联系的研究在统计学上都是微不足道的。

How oral contraceptives influence cancer risk

研究 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.

但是，在子宫内膜中，雌激素似乎会增加细胞分裂，而孕激素的作用相反。这就解释了为什么组合避孕药对某些癌症（例如子宫内膜癌）具有保护作用。这也可以解释为什么仅孕激素的节育选择（例如迷你丸或镜头）的风险较小。

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

Talk with a doctor

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 othernon-hormonalbirth control options, such as:

• 男性或女避孕套。Condomsare 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不涉及无激素，而是完全依靠跟踪您的月经周期。使用这种方法，您可以跟踪温度，宫颈粘液和其他症状，以确定何时应避免亲密关系。生育力意识在预防怀孕方面有效约76％至88％。
• Diaphragm, cervical cap, or sponge.Diaphragms,颈盖, andspongeswere 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 IUDsare the only non-hormonal option IUD option. Unlike the注入or荷尔蒙宫内宫内节育器, 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.

带走

口服避孕药是市场上最有效的节育方法之一，它们具有少数其他积极的健康益处。但是，研究表明，口服避孕药可能导致乳腺癌和宫颈癌风险略有增加。

但是研究还表明，避孕药可以降低子宫内膜，卵巢癌和大肠癌的风险。

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.