Breast cancer is one of the most commonly diagnosed cancers worldwide, yet misconceptions about what increases or reduces breast cancer risk remain common. According to the World Health Organization (WHO), breast cancer caused an estimated 694,000 deaths globally in 2024 and was the most common cancer among women in 164 of 186 countries. [1]
Breast cancer risk is influenced by many factors. Some, such as age, family history and certain inherited genetic changes, cannot be changed. Others, including alcohol consumption, physical activity and body weight, may be modifiable. Importantly, having one or more risk factors does not mean that a person will develop breast cancer.
This Breast Cancer Awareness Month, take a closer look at three common misconceptions about breast cancer risk and what the evidence tells us.
Explore more on breast cancer risk factors.
Myth #1: Using hormonal birth control means you will develop breast cancer
Fact: Research suggests that current or recent use of some hormonal contraceptives may be associated with a small increase in breast cancer risk, but this does not mean that someone who uses hormonal birth control will develop breast cancer.
Research has found a modest association between breast cancer risk and current or recent use of several types of hormonal contraception, including combined birth control pills and some progestin-only methods. A large 2023 study and meta-analysis found broadly similar small increases in relative risk among users of oral contraceptives, hormonal IUDs, implants and injections. [2]
However, these findings show an association and do not prove that hormonal contraceptives cause breast cancer. For oral contraceptives, research has also shown that the increased risk declines after use stops. Hormonal contraceptives also provide important benefits, and oral contraceptive use has been associated with lower risks of several other cancers, including ovarian and endometrial cancers.
For this reason, decisions about hormonal contraception should take into account an individual’s health history, personal risk factors, and the benefits and potential risks of different contraceptive options.
What to know: If you are concerned about breast cancer risk and hormonal contraception, speak with a healthcare professional about your individual risk factors and options.
Myth #2: Breast cancer only affects women
Fact: Although breast cancer overwhelmingly affects women, men can develop breast cancer too.
Approximately 0.5–1% of breast cancers occur in men worldwide. Men have breast tissue where cancer can develop, and although breast cancer can occur at any age, it is generally diagnosed at a later age in men than in women. [1]
Factors associated with increased male breast cancer risk include older age, family history, inherited changes in genes such as BRCA1 and BRCA2, previous radiation therapy to the chest, obesity and certain conditions associated with higher estrogen levels.
Because breast cancer in men is uncommon, routine mammography generally is not recommended for men. However, changes such as a breast lump or thickening, nipple changes or discharge should be discussed with a healthcare professional. [3]
What to know: Breast cancer is not exclusively a disease that affects only women. Everyone should be aware of unusual breast changes and seek medical advice when concerned.
Myth #3: Eating soy increases breast cancer risk
Fact: Soy foods do not appear to increase breast cancer risk and can be part of a healthy, balanced diet.
Soy contains naturally occurring compounds called isoflavones, which are sometimes referred to as phytoestrogens because they have a chemical structure similar to estrogen. Since higher exposure to estrogen is associated with some types of breast cancer, this has led to concerns that eating soy could increase breast cancer risk.
However, isoflavones do not act in the body in exactly the same way as human estrogen. Research in people has not found consistent evidence that eating soy foods increases breast cancer risk. In fact, some studies suggest that soy consumption may be associated with a lower risk of breast cancer, particularly among Asian women. [4]
Foods such as tofu, tempeh, edamame and soy milk can provide protein, fiber and other nutrients as part of a balanced diet. Soy or isoflavone supplements are different from whole soy foods, however, because they may contain much higher concentrations of isoflavones, and their effects are less well understood. Soy foods are generally recommended over supplements for cancer prevention. [4]
What to know: There is no need to avoid soy foods because of concerns about breast cancer risk. If you have been diagnosed with breast cancer or are considering high-dose soy or isoflavone supplements, discuss them with your healthcare team.
For more practical ideas, explore 8 Tips to Reduce Your Breast Cancer Risk.
Know Your Risk, Take Informed Action
There is no guaranteed way to prevent breast cancer. In fact, WHO estimates that approximately 80% of breast cancers occur in women with no specific risk factors other than sex and age. A family history of breast cancer can increase risk, but most women diagnosed with breast cancer do not have a known family history of the disease. [1]
Understanding your individual risk can nevertheless help you make informed decisions about your health. Talk with a healthcare professional about your personal and family history and what screening or risk-reduction strategies may be appropriate for you.
Research Continues to Change What’s Possible
Understanding risk and improving early detection are important parts of reducing the burden of breast cancer. At the same time, continued research is essential to developing better ways to prevent, detect and treat the disease.
Over the years, AFCR has supported research addressing breast cancer from multiple directions, including a program examining the prevalence of BRCA1, BRCA2 and other hereditary cancer-related mutations among populations in Chinese mainland and Hong Kong, as well as an innovative platform that develops multi-functional antibody therapies.
Reference:
[1] https://www.who.int/news-room/fact-sheets/detail/breast-cancer
[2] https://journals.plos.org/plosmedicine/article?id=10.1371%2Fjournal.pmed.1004188
[3] https://www.cancer.gov/types/breast/male-breast-cancer
[4] https://www.cancer.org/cancer/latest-news/soy-and-cancer-risk-our-experts-advice.html
