Birth Control and Breast Cancer: Are They Linked?

For many individuals, the thought of breast cancer conjures feelings of fear and uncertainty. The emotional weight becomes even more profound when considering the potential link between breast cancer and birth control. Understandably, this connection can leave them feeling apprehensive, especially if birth control is essential to an individual’s healthcare.

One of the main concerns revolves around the use of hormonal contraceptives, such as birth control pills. These contraceptives contain synthetic hormones that regulate the menstrual cycle and prevent pregnancy. Many studies found no association between birth control and breast cancer risk, while others found that birth control is associated with a very small increase in breast cancer risk that disappears soon after one stops using birth control. The uncertainty surrounding this link can be emotionally taxing, causing anxiety and distress for those seeking safe and effective birth control options. Equipping oneself with knowledge on this topic may bring more awareness to make more informed decisions.

Fortunately, not all birth control methods are associated with an increased breast cancer risk. The birth control methods that may cause a small increase in breast cancer risk are hormone-based. This type of birth control makes use of the release of hormones, whether natural or manmade, to prevent pregnancy. Common hormonal birth control methods that may have some links to breast cancer include:

• Oral contraceptives

Oral contraceptives, or birth control pills, are medications containing hormones taken orally to prevent pregnancy. The primary mode of action of oral contraceptives is the inhibition of ovulation, where they prevent follicle-stimulating hormone (FSH) levels from rising, thus impeding the development of ovarian follicles and preventing ovulation. Oral contraceptives also work by preventing sperm from penetrating through the cervix by affecting the cervical mucous environment.

• Combination pill

The combination pill contains synthetic versions of two natural female hormones, estrogen and progesterone.

• Progestin-only pill (POP)

The POP, also commonly known as the mini pill, contains only progestin—a class of synthetic hormone drugs that mimics progesterone’s endogenous hormone.

Many large observational studies and prospective cohort studies have not found any association between combined estrogen-progestin oral contraceptives and breast cancer risk. In other studies, the small increase in risk disappears within 2–10 years. While the increase in risk is around 20%–30% in some studies, the absolute risk of developing breast cancer in young women who take birth control is very low. Thus, the number of additional cancer cases among combined contraceptive users was 1 new case among 7,690 women per year and 1 new case for 50,000 women per year for women older than 35.

• Hormonal intrauterine devices (IUDs)

A hormonal IUD is a small, T-shaped contraceptive device that is inserted into the uterus to prevent pregnancy. It releases a low dose of progestin hormone called levonorgestrel into the uterine cavity. This hormone thickens the cervical mucus, making it difficult for sperm to reach the egg. Additionally, in some cases, it may suppress ovulation, further reducing the chances of pregnancy.

Studies involving hormonal IUDs have shown mixed results, with some showing no association in with breast cancer and others showing up to 20% increase over the overall low absolute cancer risk. Additional research with more patients is needed.

There are other types of hormonal birth control methods. However, not enough studies have been conducted on them to suggest any links to increased breast cancer risk. These include:

• Contraceptive implants
• Birth control patches
• Vaginal rings

Estrogen and progesterone are naturally occurring hormones that can stimulate the growth of breast cancers that express receptors for these hormones. As hormonal birth control methods contain synthetic versions of these hormones and mimic their functions, they could also potentially increase cancer risk. For this reason, hormonal birth control methods are not advised to be used for women with a personal history of breast cancer.

While it seems like hormonal birth control methods such as oral contraceptives may be “bad” for your health due to their associations with breast cancer, it may be an unfair and premature conclusion, especially for those who may need to rely on birth control methods for other medical reasons. In fact, many birth control methods have additional benefits besides preventing pregnancy. Interestingly, the same oral contraceptives that may potentially increase breast cancer risk have shown the potential to decrease the risk of other cancers, such as ovarian, endometrial, and colorectal cancer. Therefore, avoiding birth control solely on the potential increased risk of breast cancer may not be the wisest. Furthermore, while hormonal birth control methods may increase the absolute risk of breast cancer, the risk itself is very low. For example, the risk of being diagnosed with breast cancer in the next 10 years is 0.1% for a 20-year old woman, 0.5% for a 30-year old woman, 1.5% for a 40-year old, and 2.4% (1 in 42) for a 50-year old woman.

There are also non-hormonal birth control methods that have not shown links to breast cancer, such as:

• Condoms

Male condoms and female condoms are physical barriers that prevent sperm from entering the vagina during sexual intercourse. They also provide some protection against sexually transmitted infections (STIs).

• Diaphragms and cervical caps

These are dome-shaped devices that cover the cervix and block sperm from entering the uterus. They are used with spermicide to increase effectiveness.

• Copper intrauterine devices (IUDs)

Copper IUDs, such as ParaGard, are T-shaped devices that contain copper. Copper is toxic to sperm and prevents fertilization. Copper IUDs can provide contraception for up to 10 to 12 years.

• Spermicides

Spermicides are chemical substances in the form of gels, foams, creams, or suppositories that immobilize and kill sperm. They are used alone or in combination with barrier methods.

• Sterilization

Tubal ligation (for females) and vasectomy (for males) are permanent methods of contraception that involve surgical procedures to block or cut the fallopian tubes or vas deferens, respectively.

It's crucial to understand that a combination of factors, including age, family history of breast cancer, lifestyle factors, and reproductive history, influences individual breast cancer risk.

If you have concerns about breast cancer risk and birth control, discussing your options with a healthcare provider is essential. Their expertise and guidance can give you insights into your specific cancer risks and how your chosen method of birth control might influence those risks. They can then provide personalized advice based on your health history and help make informed decisions about the most suitable contraceptive method. Additionally, regular breast self-exams, clinical breast exams, and mammograms (as recommended for age-appropriate screening) can aid in early detection and improve outcomes if breast cancer does develop. This proactive approach can lead you to make informed decisions about your health and well-being.