10 Common Breast Cancer Risk Factors

By Wendy Innes. May 7th 2016

Breast cancer is one of the most common forms of cancer, but the good news is that it's also one of the most treatable, as long as it's caught early. One of the ways that people can ensure that it is caught early is to know their risk factors. Those who have increased risk factors for developing breast cancer can have their doctor begin screening for it earlier. Here are 10 common risk factors for developing breast cancer.

Being A Woman

The vast majority of breast cancer cases affect women. However, this doesn't mean that it's impossible for men to develop breast cancer. In fact, the American Cancer Society estimates that in 2012, nearly 2,200 men will develop breast cancer and just over 400 will die from it. However, just being a woman already places a person at risk for developing breast cancer.


There are certain genes that are passed from parent to child that make a person more susceptible to developing cancer. There are two genes, called BRCA1 and BRCA2, which can have abnormal mutations that lead to breast cancer. Everyone has these genes and they are responsible for the health of breast tissue, but when they are abnormal, breast cancer can develop. The good news is that those with a family history of breast cancer have the option of being screened for these mutations, which means that it's possible for individuals to know in advance if they have this increased risk.

[Related – Breast Cancer Screening Guidelines]

Race And Ethnicity

Caucasian women have a slightly higher risk of developing breast cancer, but African-American women have a higher risk of developing more aggressive, advanced stage cancers at a younger age than other demographics of women. Because of this, African-American women are also more likely to die from breast cancer.


As with many other diseases and conditions, the risk of developing breast cancer increases as a person gets older. In fact, two out of three cases of invasive breast cancer are diagnosed in women over the age of 55. Because of this, doctors will usually start screening women around the age of 40, unless they have other risk factors or they request earlier screening. And while no one can do anything about growing older, people can grow older and be healthier.

Being Overweight

Women who are overweight have a statistically higher incidence of breast cancer than women who are not overweight. Being overweight is defined as having a body mass index (BMI) over 25. This risk is caused by fat cells. Fat cells produce estrogen, and breast cancer tumors are often called "estrogen dependent" tumors. The location of the extra weight matters as well. Extra fat around the belly may cause more of a risk than extra fat in the thighs and buttocks, but more research is needed to determine why this is.

[Related – The Difference Between Overweight And Obesity]

Not Having Children

There are many benefits to having children, and one of them is the decreased risk of breast cancer. The reason is that breast tissue begins growing in adolescence, but breasts remain somewhat immature with active growth until a woman goes through her first full-term pregnancy. The most benefit is seen in women who have children before the age of 30. The hormones associated with pregnancy help to mature breast tissue and reduce the risk of cancer.

Not Breastfeeding

Breastfeeding is the healthiest way to feed a baby, but there are added benefits to the mother as well. Aside from plenty of uninterrupted cuddle time with baby, breastfeeding for at least the baby's first year has been shown to reduce the risk of breast cancer. There are a number of reasons for this. Breast tissue that is making milk 24 hours a day has less of a chance to misbehave as well as limiting the number of menstrual cycles that a woman has in her lifetime, thereby lowering her estrogen levels and reducing the likelihood of developing estrogen dependent breast tumors.

Family History

There is ample evidence to indicate that a woman with a first-degree family member with breast cancer (mother or sister) have twice as high a risk of developing breast cancer as someone who doesn't. A person with two first-degree family members is five times as likely to develop breast cancer. There is an even higher risk for those who have male first-degree relatives with breast cancer, though researchers aren't exactly sure how much of an increased risk exists.


It is no secret that cigarettes contain some of the most shocking chemicals known to man, many of which are known carcinogens, which means that they cause cancer. So aside from a woman's clothes, hair and breath smelling bad and looking bad, she is increasing her risk of developing breast cancer significantly each time she lights up. The good news is that the benefits of quitting can be seen almost immediately and it's never too late to quit.

[Related – How Smoking Affects Your Health]

Hormone Replacement Therapy (HRT)

Hormone replacement therapy has been widely used by postmenopausal women to help ease the bothersome symptoms associated with menopause such as hot flashes and fatigue. However since the link between HRT and breast cancer was discovered in 2002, many women have opted to skip the hormones. But many more continue to use them and there is reason to believe that even those women who stopped using them have an increased risk of developing breast cancer because of the increased amount of estrogen in the body.

[Related – Menopause And Hormone Replacement Therapy]

These are just 10 of the most common risk factors for developing breast cancer. If a woman is concerned about her risk, she should talk with her doctor about screening, because the key to survival is early diagnosis and treatment until there is a cure.


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