Breast Cancer Risk and Prevention

Breast cancer is one of the most common cancers in women. About 1 in 8 women will develop breast cancer in their lifetime. Men are also at risk of breast cancer, but this risk is much lower than it is for women. This article will talk about breast cancer risk and prevention in women only.

Some risks for breast cancer can be modifiable, meaning you can change them (diet, weight, exercise, alcohol use, etc). Others are nonmodifiable, meaning they can’t be changed (age, family history, starting your period at a young age).

Risk factors can increase your chance of breast cancer, but they do not mean that you will get cancer. About 70 out of 100 women who get breast cancer do not have any risk factors and more than 85 out of 100 have no family history of the disease. Because of this fact, all women should talk about screening for breast cancer with their providers.

The following are risk factors for breast cancer and ways you can lower your risk of the disease.

Age

The risk of breast cancer is higher as you get older. More women get breast cancer in their 60s and 70s than in their 30s or 40s.

Your Health History

Your health history can raise your breast cancer risk:

• Women who have their first menstrual period before age 12, or who go through menopause later (after age 55), have a slightly higher risk of breast cancer. This is thought to be from a longer lifetime exposure to estrogen in their bodies.
• Some studies have shown that breastfeeding can reduce risk. This may be related to the number of menstrual periods and estrogen levels in your body.
• The age of a woman at her first live birth of a child can affect risk, but the effect depends on the number of first-degree relatives who have been diagnosed with breast cancer. For women with 2 or more 1st-degree relatives (mother, sister) with a diagnosis, their risk decreased with an older age at first live birth. For women with no family history, the risk increases with older age at first live birth.

Breast Biopsies

If you have had a breast biopsy, your risk is higher. Two biopsy results have more effect on risk. Atypical hyperplasia is not a cancer but increases the risk of breast cancer by 3-5 times. Lobular carcinoma in situ (LCIS) are cancer cells found only in the lobules in the breast tissue. LCIS is not treated like other breast cancers, but you will be watched closely for cancer, and you may have to take medication to lower future risk. Having LCIS means your risk of breast cancer is 7 to 11 times higher than an average woman.

Women who have had a biopsy showing atypical hyperplasia or LCIS should have screening every year with mammography and exams by a healthcare provider 1-2 times a year. Some women may also have MRIs for screening. You should talk about this with your provider.

The Breast Cancer Risk Assessment Tool looks at many of these above health factors, especially history of biopsy, and comes up with an estimated risk of developing breast cancer in the next 5 years and in your lifetime. The results are based on the Gail Model which figures out risk. Learn more about the Model or use the tool.

Hormone Replacement Therapy (HRT)

Menopausal hormone replacement therapy (HRT) is the use of medications that contain hormones to help manage the side effects of menopause. Side effects of menopause can be hot flashes, vaginal dryness, the risk of bone fractures, and heart disease.

Studies done in 2002 by the Women’s Health Initiative (WHI) found that HRT may increase the risk of breast cancer, heart disease, stroke, and blood clots. In the early 2000s, HRT was thought to do more harm than good, and people were not taking it as often.

In more recent years, studies have found that if you take estrogen-only HRT, there is little to no increased risk of breast cancer. It also does not increase the risk for heart disease, stroke, or blood clots. Taking HRT does not increase the risk for ovarian cancer or lung cancer, and taking it can actually lower your risk of colorectal cancer. If you take estrogen plus progestin HRT, the increased risk of breast cancer is 0.005%. You should not take HRT if you have breast cancer or had it in the past. Often, if you have menopausal symptoms, you will take HRT for 2 to 5 years. Talk to your provider if you are taking it for 5 years or longer or if you are over the age of 60. Research is ongoing about the benefits and risks of HRT.

Birth Control Pills & Cancer Risk

Since birth control pills (BCPs) came out in the 1960s, the ingredients have changed. Early BCPs had 150 micrograms of ethinyl estradiol, whereas today's BCPs have about 20 micrograms. These changes make it hard to apply the results of previous studies to today's BCPs.

More recent studies of modern BCP doses have found no increase in breast cancer risk among current or former users. It is not known whether the newer forms of BCP have the same effect on endometrial and ovarian cancers.

Increased screening is not needed for women who have taken birth control pills.

Learn more about birth control pills and cancer risk at Oncolink.org.

Personal History of Breast Cancer

If you have had breast cancer in the past, you are 3 to 4 times more likely to get breast cancer again compared to a woman who has never had the disease (not metastases or spread from the first cancer, but a new cancer). This new cancer may happen in the same breast or the other breast. It is important to keep follow-up appointments with your oncology team and continue recommended screening tests.

Family History of Breast Cancer

Your risk is partly based on how closely related you are to family members with cancer and at what age the woman in your family was diagnosed.

• If you have a first-degree relative (sister, mother, daughter) with a breast cancer diagnosis, your risk is double that of someone without a family history.
• Having two first-degree relatives makes the risk even greater.
• If your father or brother has had male breast cancer, your risk is also increased.
• If you are someone with a first-degree relative(s) with the disease, you may need to start getting mammograms done at an earlier age than the American Cancer Society suggests. Talk about this history with your healthcare providers about hereditary cancer syndromes. Ask your provider if you should see a genetic counselor to talk about genetic testing.

If you have a more distant relative with breast cancer, your risk becomes less certain. If your family history has a few people diagnosed with the same cancer or diagnosed before age 50, you should talk with a genetic counselor. If not, standard screening is often recommended (mammogram every year, beginning at age 40). Talk to your provider about when you should start screening.

Genetic Factors

About 5 to 10 out of 100 cases of breast cancer are inherited (or hereditary), meaning that a damaged (mutated) gene was passed down from a parent to a child. BRCA 1 & 2 are the most common and well-understood mutations, but they are not the only ones that can increase breast cancer risk. You can read more about other genetic mutations in our article Genetic Testing for Familial Breast Cancer.

You should talk with a genetic counselor if you are worried about your family history. You should be screened if you have any of the following:

• Multiple family members who have been diagnosed with breast or ovarian cancer, especially before age 50.
• Family members who have had bilateral breast cancer (in both breasts).
• Both breast and ovarian cancer are present in the family.
• There are any cases of male breast cancer in the family.
• In addition to breast cancer, family members on the same side of the family who have had prostate cancer (at a young age), colorectal cancers, stomach cancer, pancreatic cancer, and endometrial cancer.
• Your family is of Ashkenazi Jewish heritage.

BRCA1/BRCA2 Genetic Predisposition

The most common cause of hereditary breast cancer is an inherited mutation in the BRCA1 or BRCA2 gene. If you have inherited a mutated copy of either gene from a parent, you have about a 40-85% chance of developing breast cancer during your lifetime. People with these mutations tend to develop cancer at a younger age (before age 40) and these cancers more often affect both breasts. People with these inherited mutations also have a higher risk of other cancers, like ovarian cancer, male breast cancer, pancreatic cancer, and prostate cancer. BRCA mutations occur more in people of Ashkenazi Jewish (Eastern European) descent, as well as Norwegian, Dutch, and Icelandic populations, but they can happen in any racial or ethnic group.

If you know that you have a BRCA 1 or BRCA2 mutation, you should talk to a healthcare provider to make sure you have the proper screening or treatment (chemoprevention) to lower the chance of cancer or to find cancer earlier when treatment is most effective. Your healthcare provider may suggest getting mammograms at a younger age, special breast and/or ovarian cancer screening tests, or other interventions, like prophylactic (preventative) surgery or chemoprevention.

Diethylstilbestrol (DES) Exposure for Mothers & Daughters

Diethylstilbestrol (DES) was the first synthetic (manmade) estrogen. Estrogen is a type of hormone that is responsible for female sex characteristics. It was given to pregnant women from 1938-1971. It was thought to prevent miscarriages and help healthy pregnancies. Not only did the drug not work, but it also caused health issues for the women taking it, as well as children born of these pregnancies. Women who took DES have been found to have a greater risk of breast cancer.

Learn more about this risk and recommendations for screening.

Previous Chest Radiation

Women who had radiation therapy to the chest area as treatment for another cancer (like Hodgkin disease) have a much higher risk of breast cancer. The risk depends on the age at which they were treated. Risk is highest for those treated as adolescents, while breast tissue was developing. Treatment after age 40 does not seem to increase breast cancer risk. For Hodgkin's disease survivors who had radiation to the chest or axilla (armpit area), recommendations are:

• Annual breast exam by a healthcare professional, and monthly self-breast exam.
• Begin annual mammograms 8-10 years post-therapy.
• Breast MRI, in addition to the annual mammogram.

Speak to your provider about when you should start mammograms and breast MRI as screening. Learn more about what to do if you have had radiation to your chest area at Oncolink.org.

Alcohol Use and Breast Cancer Risk

Alcohol can also increase your risk of many types of cancer, including breast cancer. Alcohol seems to increase the levels of estrogen in the body and can increase the risk of hormone positive breast cancer (also called ER+ or PR+).

The risk of cancer for heavy drinkers is 10-15 times higher than it is for those who do not drink. The overall risk increases after just 1 drink a day for women or 2 for men. One drink means 12 ounces of regular beer, 5 ounces of wine, or 1.5 ounces of 80-proof liquor. Higher breast cancer risk has been linked to just 3 drinks a week, so the risk is not limited to heavy drinking. Women who have 2 alcoholic drinks a day are 1.5 times more likely to develop breast cancer than a woman who never drank alcohol.

Learn more about how alcohol causes cancer and resources for quitting at Oncolink.org.  

How to Reduce Breast Cancer Risk

The Prevention Triangle: Diet, Activity & Healthy Weight

A healthy diet, regular physical activity, and keeping a healthy weight have been shown to reduce cancer risk. This triangle is thought to be the second most important step, after not smoking, in preventing cancer. Being overweight and having a diet high in fat is related to breast cancer. Research has also shown that being overweight increases the risk of recurrence in a woman who has had breast cancer.

Learn more about how the prevention triangle can help to prevent breast cancer.

Chemoprevention

Chemoprevention is the use of medications to prevent cancer. Tamoxifen was the first chemoprevention medicine to receive FDA approval. The Breast Cancer Prevention Trial showed that tamoxifen reduces a pre-or post-menopausal high-risk woman's chances of breast cancer by as much as one-half.

Raloxifene is another selective estrogen receptor modulator (SERM) that can prevent breast cancer in postmenopausal women. This medication is also used to prevent and treat osteoporosis. Raloxifene also works by blocking estrogen's effects in the breast and other tissues but seems to have fewer risks than tamoxifen. Raloxifene doesn't exert estrogen-like effects on the uterus, so there is no increased risk of endometrial cancer.

The National Surgical Adjuvant Breast and Bowel Project studied both tamoxifen and raloxifene for breast cancer chemoprevention in the STAR trial. Women took either tamoxifen or raloxifene daily for five years. The results showed that tamoxifen and raloxifene both reduced the risk of invasive breast cancer in high-risk women by about 50%.

The decision to use chemoprevention medications is personal and you should talk with your healthcare provider about the risks and benefits of this therapy.

Your risk of breast cancer and screening recommendations is based on your personal history and goals. Talk with your provider about your risk and your options for screening.