Are You At Risk?

Understanding Risk Factors for Breast Cancer

While our understanding of what initiates and promotes the development of breast cancer in any given woman is imperfectly understood, we do recognize broad categories of circumstances that elevate a woman’s risk.

Personal History

The strongest risk factor for developing breast cancer is having had it once before. In addition, women who have had benign biopsies showing either “atypical hyperplasia” or “lobular carcinoma in situ” (LCIS) are at significant risk for developing malignant disease in the future.

Genetics and Family History

Women with a first degree relative (mother or sister) with breast cancer are at increased risk for developing the disease themselves. This risk is magnified if their family member’s disease was diagnosed before the age of 50. Having a more distant relative, like a grandmother, cousin, or aunt, from either the father’s or the mother’s side, elevates the risk as well, but not to the same extent.

While we once had two genes, BRCA-1 and BRCA-2, we now know of many more, including PALB2, CHEK2 and others which participate in the development of both breast and ovarian cancer. Women who have mutations or changes in these genes have an up to 85% chance of developing breast cancer in their lifetime along with an increased risk of ovarian cancer as well. These women generally develop their cancer at a younger age (40s or younger), and the disease may be in both breasts. When one of these genetic mutation runs in a family, multiple family members on either the mother’s or the father’s side may have breast or ovarian cancer, as well as a number of other types of cancers. Any woman who fits this profile should consider consultation with a genetics specialist to more accurately assess her risk for carrying these genetic mutations.

Hormonal and Environmental Exposures

Hormonal Exposure

Most breast cancers are promoted by exposure to estrogen and progesterone, two hormones made naturally by the ovaries as soon as a woman starts menstruating. The ovaries stop making these hormones at menopause and their production is altered during pregnancy. As a result, women who begin menstruating early, enter menopause late, and either delay childbearing beyond the age of 30 or forgo it altogether, are exposed to high levels of these hormones which increases their risk for developing breast cancer.

Hormone replacement therapy after menopause can also increase a woman’s risk. A recent large scale study of women taking combination estrogen and progesterone after menopause showed an increased incidence of breast cancer as well as heart disease and stroke. While the numbers of these events were modest, the fact that they occurred warrants careful consideration of the risks and benefits of hormonal replacement therapy. Women on this type of hormone replacement should have a discussion with their physician regarding the relative risks and benefits particular to their situation.

Environmental Exposures

Exposure to radiation of the chest, such as that delivered in the treatment of some lymphomas, may lead to breast cancer later in life. Alcohol consumption even in moderate amounts has also been related to an elevated risk, but this effect is eliminated if those whose diets include adequate folate, a B vitamin found naturally in whole grains and vegetables as well as in most multivitamin supplements.

Lifestyle Choices

In general, women who maintain ideal body weight have a lower incidence of breast cancer. This effect probably operates through lowering the amount of estrogen that we know is produced by fatty tissue. Similarly, taking hormone replacement after menopause has been shown in a recent large clinical trial to increase a woman’s risk of developing breast cancer. The number of breast cancer events in this trial was small but the relationship is undeniable. Given this information, those women who already have significant risk factors for breast cancer may want to avoid even the small additional risk that hormone replacement therapy confers.

Dietary choices can also impact the incidence of cancer in general, though this relationship is less well understood. A diet rich in green leafy vegetables, which contain beta carotenes, seems to protect against a number of cancers. Similarly, soy based diets are associated with low rates of cancer overall, though there is some controversy regarding its use in preventing breast cancer as soy is a phytoestrogen and may hypothetically provide a growth factor for this type of cancer. Moderate alcohol consumption has been linked to an increased incidence of breast cancer, but this risk may be mitigated by ensuring an adequate intake of folate, a B vitamin found in whole grains. A number of other nutritional therapies aimed at cancer risk reduction are very provocative but rigorous scientific testing of these therapies has not yet been done. Fortunately, this is an area of emerging scientific interest and we will be hearing more about clinical trials involving natural therapies in the future.

Genetic Testing

Breast cancer becomes a common disease among women after the age of 50. It usually affects only one breast, is driven by female hormones, and is not usually accompanied by multiple other relatives with breast cancer or other malignancies. When we see women whose breast cancers develop at a younger age, affect both breasts, have unusual features like “triple negative breast cancer," or cluster in families along with other less common malignancies such as ovarian or pancreatic cancer, we know that cancer may be caused by an abnormal gene, also known as a genetic mutation, that can be identified by genetic testing. Recognizing those who are good candidates for genetic testing is an important part of the breast evaluation, and the results of that testing can dramatically change treatment options. In addition, family members of the mutation carrier can be tested for the same abnormality so that they can understand their own risk and take appropriate action.

BRCA-1 and 2 were the first two breast cancer gene mutations identified, and they are accompanied by significant risks of ovarian cancer as well. For carriers of these mutations, enhanced surveillance or risk reduction surgery have clear roles in risk management. Other gene mutations such as CHEK2 and PALB2 can also be associated with an increased risk of breast cancer, though they are not associated with ovarian cancer in the same way that BRCA-1 and 2 are. Still other gene mutations link breast cancer to colorectal cancer (Lynch syndrome), uterine cancer (PTEN), or brain tumors (TP53). As you can see, understanding the genetics of cancer is complicated and genetic counselors are specifically trained to guide patients through the process of testing and risk management. Your Breast Surgeon has a key role in this process and should initiate the conversation and direct you to the appropriate resources in a timely fashion. If risk reduction surgery is elected, your Breast Surgeon works with a Plastic Surgeon to achieve the desired cancer risk reduction while achieving the best cosmetic outcome.

shutterstock 233304142When cancer is caused by an abnormal gene, also known as a genetic mutation, it can be identified by genetic testing.  

Reducing Your Risk

Women who have significant risk factors for breast cancer should consider risk reduction strategies that can help her avoid developing the disease. Women who benefit most from these strategies are those who have a family history of breast cancer in a mother or sister, those with a breast biopsy showing either “atypical hyperplasia” or “lobular carcinoma in situ,” (LCIS) and those who are carriers of the BRCA 1 or 2 gene mutation. A cancer specialist can help her decide if some type of preventive measures are appropriate for her. Options currently available are both medical and surgical.

Tamoxifen or Raloxifene

These estrogen blocking drugs have been shown to significantly decrease the risk of developing breast cancer in high risk women. Each is a pill taken daily for 5 years and they essentially make the breast uninviting to a developing cancer by blocking one of the cancer’s primary growth factors. Side effects that may be experienced include hot flashes and a small risk of uterine cancer and blood clots. Tamoxifen can be used in both premenopausal as well as postmenopausal women, but roloxifene is only appropriate in post menopausal women. Many women have taken raloxifene (Evista) for its known bone building effects and it seems to be particularly well tolerated. A new class of estrogen modulating drugs, the aromatase inhibitors, (Femara, Arimidex) show great promise as a preventative agent in postmenopausal women, and a national trial testing this drug for that purpose is planned.

Prophylactic Mastectomy

This option is appropriate only after careful consideration of its attendant risks, both physical and emotional, along with a realistic discussion of its degree of benefit in reducing a woman’s chance of developing breast cancer. Clearly, women at highest risk are those who stand the most to gain from this preventative measure.

Carriers of the BRCA-1 or 2 gene mutations have an up to 85% lifetime risk of developing breast cancer. Prophylactic mastectomy reduces this risk by about 90%. Prophylactic oophorectomy further reduces their risk as detailed below.

Women who have lesser risk factors, such as a strong family history of breast cancer but without a genetic mutation, may also benefit from prophylactic mastectomy, but the absolute degree of the benefit is less. These women should be carefully counseled regarding non-surgical options for risk management. But, if the anxiety produced by managing her risk outweighs the benefit of preserving her breasts, prophylactic mastectomy is a reasonable way to provide her with the assurance she needs to get on with her life.

You may have heard the term nipple-sparing mastectomy, which is a form of prophylactic mastecotmy. 

Read More About Nipple-Sparing Mastectomy »

Prophylactic Oophorectomy

In women carrying the BRCA 1 or 2 gene mutation, surgical removal of the ovaries reduces the incidence of breast cancer by at least 50%. This procedure in combination with a close breast cancer surveillance program for early detection gives these high risk women a realistic option for managing their risk without resorting to mastectomy. High risk women who don’t have a genetic mutation do not enjoy the same breast cancer protection from this procedure so they are not routinely offered it.