Some Questions, Some Answers: Birth Control Pills, Fertility Drugs and Breast Cancer Risk

The following post was written by Susan G. Komen.

It’s well established that hormones play a key role in breast cancer risk.So, it’s not surprising that factors related to fertility and pregnancy have been actively studied to better understand their relationship with breast cancer. These include, age at menopause, age at first period, childbearing (number of children and age at first childbirth) and use of menopausal hormone therapy (postmenopausal hormones).

The potential link between birth control pills and breast cancer has also been well studied. And, studies have looked at a possible link between the use of fertility drugs and breast cancer. At this time, results from these studies point to some solid conclusions, with some results still up in the air. These findings and other issues related to birth control pills and fertility drug are discussed below.

Birth control pills

Are there different types of birth control pills?

Birth control pills often get lumped together into a single group, but there are actually many different oral contraceptive options. Most contain a mix of the hormones estrogen and progestin. The exact amounts and types of these hormones vary depending on the specific pill. Some types of birth control pills and other contraceptives contain only progestin.These include the injectable contraceptive Depo Provera and what’s often called the “mini-pill.”

Birth control pills contain the same types of hormones included in menopausal hormone therapy (used to manage menopausal symptoms). However, there are important differences. These medications contain different amounts of hormones and they are used during different stages of life for different purposes.

Do birth control pills raise the risk of breast cancer?

Women who take birth control pills have a slightly increased risk of breast cancer (about 20 to 30 percent) compared to women not on the pill.1-2 This extra risk, though, is quite small because the risk of breast cancer for most young women is low.1-2And, the extra risk goes away fairly quickly after women stop taking the pill.1-2 Four years after stopping, breast cancer risk linked to the pill drops by half.Nine years after, it nearly goes away completely.1-2

Are there other risks with birth control pills?

In addition to an increased risk of breast cancer, birth control pills can also raise the risk of blood clots and heart attack, especially in women who smoke and those age 35 or older.3-4

Do birth control pills affect the risk of other cancers?

The most obvious benefit of birth control pills is that they prevent pregnancy, but they have also been shown to lower the risk of two types of cancer – ovarian cancer and colon cancer.

For colon cancer, using the pill for eight years or more has been shown to lower the risk of the disease by around 40 percent.5 For ovarian cancer – a cancer with few risk factors that are under a woman’s control – long-term use of the pill can lower risk by as much as 50 percent.5

What’s the bottom line on birth control pills and breast cancer?

Birth control pills have both risks and benefits. The risks are lower for younger women than for older women. Even though the risk of breast cancer and heart attack are increased while women are taking the pill, most women who take the pill are young. Therefore, these women are at very low risk overall of developing those conditions, so the absolute increase in risk is small.

For most young women, the benefits of birth control pills will outweigh the risks, especially since the breast cancer risk drops when a woman stops taking them. However, before you begin taking birth control pills (or if you are currently taking them and haven’t done so already), it’s best to discuss their benefits and risks with your health care provider.

Find a summary of research studies on birth control pills and breast cancer.

What about the “mini pill” and Depo Provera?

Newer types of contraceptives – like the “mini pill” and Depo Provera – are not as well studied as standard birth control pills. Overall, the evidence to date shows no solid links to an increased risk of breast cancer.6-7 Some findings suggest that long-term current use of Depo Provera may raise risk.6-7 but better data on Depo Provera and other less common forms of birth control pills are needed before the true risks and benefits are known.

Fertility Drugs

Similar to birth control pills, fertility drugs impact reproduction and hormone levels. Fertility drugs have also been studied as a possible risk factor for breast cancer.

Do fertility drugs raise the risk of breast cancer?

Fertility drugs are used by women to help improve their chances of getting pregnant. The drugs work by stimulating the ovaries, which increases the levels of certain hormones in the body. Because higher hormone levels are linked to breast cancer risk, fertility drugs have been studied as a potential breast cancer risk factor.

To date, though, no solid links have been found between fertility drugs and breast cancer, including clomiphene or gonadatropin.8-9 Some studies have found an increased risk, some a decreased risk, and some no risk at all.

Longer term studies and studies of newer fertility treatments should provide better information and help clarify the issue in the coming years.

Do fertility drugs have other potential cancer risks?

There are no established links between fertility drugs and other cancers. Some studies have suggested an increase in the risk of endometrial (uterine) cancer as well as ovarian cancer with use of fertility drugs.9 However, other studies have not shown increased risks and thus, results have been mixed.These potential links remain an active area of research.

What’s the bottom line on fertility drugs and breast cancer?

For some women who are having trouble getting pregnant, fertility drugs can help. While the use of fertility drugs does not appear to increase breast cancer risk at this time, studies with longer-term data are needed to confirm these findings. If you have any concerns about breast cancer risk due to fertility treatment, talk to your health care provider.


I’m the Living with Cancer blog editor. My name is Connie and I work in Woman’s Marketing Department. Follow this blog and our posts will arrive in your email.

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