Breast Cancer Risks
Every woman is at risk for breast cancer and her risk increases with age. A woman in the general population faces about a 13% lifetime risk of developing breast cancer. This risk remains low before age 50; the majority of risk occurs after age 60. Women with a BRCA1 or BRCA2 mutation have a much higher lifetime risk for breast cancer, and much of the risk occurs at a younger age. However, experts don’t agree on the exact lifetime risk figures for women with either mutation because different studies of families with BRCA mutations identified different lifetime risks.
Factors such as hormone exposure, environmental exposures, diet, exercise, and other genes, can effect cancer risk, both in people with BRCA mutations and people who do not have a mutation.
As new research continues, the ability of medical experts to predict breast cancer risk will improve. It is important to consult with a specialist in cancer genetics when determining your risk for breast cancer and making risk-management decisions that are best for you. Stay in contact with a genetics expert for updates on current knowledge.
Confronting your personal cancer risk can be confusing and frustrating. If you're high-risk and trying to make risk-management decisions, you need as much support as possible. It helps to speak with other women in the FORCE community who have faced these risks.
In women with a BRCA mutation who have never had a diagnosis of cancer, the lifetime risk for breast cancer is very high. Experts don't agree on the exact risk but estimates range from 55% - 85% lifetime risk for breast cancer for women with a mutation in either gene.
An October 2003 study of women carrying one of the three BRCA1 or BRCA2 mutations common in Jewish populations indicated a lifetime breast cancer risk of about 85%. This Power Point presentation shows a decade-by-decade breakdown for breast cancer risk in BRCA carriers compared to the general population according to this study. Different research involving many families with BRCA mutations (not specifically Jewish families) showed a comparatively lower breast cancer risk in women with BRCA mutations: 65% by age 70 for women with a BRCA1 mutation and 45% by age 70 for women with a BRCA2 mutation. Another study combined multiple studies to determine an average risk for breast cancer. This "meta-analysis" determined the average lifetime risk to be 64% in BRCA 1 mutation carriers and 56% in BRCA 2 mutation carriers.
Research, including a recent study, has shown that more recent generations of BRCA mutation carriers have a higher lifetime risk for breast cancer than prior generations. Several factors including lifestyle (diet, weight, and exercise), reproductive choices (number of pregnancies and age at the time of pregnancies), exposure to certain viruses or chemicals, and other genes may account for these differences.
Families with a strong family history of breast cancer but no identified BRCA mutation may still have increased inherited risk for cancer. Experts estimate the women in these families to have a lifetime risk for breast cancer of about 25%. It is important for anyone with breast cancer in their family to speak with a genetics expert to better understand their risk for cancer.
Breast cancer survivors with a BRCA mutation, who choose breast conservation to treat their breast cancer are at higher risk for another cancer in either breast than a woman with sporadic breast cancer. Although exact risk depends on a woman’s age and other factors, one study found BRCA carriers diagnosed with breast cancer have a 14% chance within ten years of developing the disease in the same breast, and a 37% chance within ten years of developing the disease in the opposite breast. Another study found a 40% chance for BRCA carriers to develop cancer in the opposite breast as well within 10 years of their initial diagnosis. The risk for a second breast cancer among women who develop sporadic cancer is about 10%. A 2010 study indicated that compared to women without hereditary cancer, a women with a BRCA mutation have a chance of a new breast cancer diagnosis that is up to 5 times more likely.
Because of the risk for a second cancer diagnosis, many breast survivors who learn they have a BRCA mutation choose bilateral mastectomy rather than lumpectomy and radiation. Genetic testing in women newly-diagnosed with breast cancer can help the decision-making process. Breast cancer survivors who are concerned that their cancer may be due to a BRCA mutation should speak with a genetics expert about testing.
Ovarian cancer survivors who have a BRCA mutation are at higher risk for breast cancer than women with sporadic ovarian cancer. The exact risk for breast cancer after ovarian cancer is unknown, but may depend on a number of factors. Research indicates that ovarian cancer survivors with a BRCA mutation survive longer than average compared with ovarian cancer survivors with sporadic cancer, so it is important for ovarian cancer survivors to understand their risk for breast cancer and take appropriate steps to manage their risk.
Genetic experts can help ovarian cancer survivors with a BRCA mutation determine their risk for breast cancer and develop a risk management plan.
Anyone, male or female can get breast cancer, but generally, men are much less likely to develop the disease than women. Men who carry a BRCA mutation have a higher risk for breast cancer than men in the general population. However, the risk is still fairly low. Several small studies have determined the lifetime risk for breast cancer to be about 2% in men with BRCA1 mutations and about 8% in men with BRCA2 mutations. This is compared to a breast cancer risk in the general male population of about 0.1% (1 in 1000 men).
About 8% of men with breast cancer carry a BRCA mutation. This percentage is higher among male breast cancer patients who are of Jewish descent. Any man with breast cancer should consult with a genetics expert to determine if they would benefit from BRCA testing.
Most breast cancer occurs in women without a BRCA mutation. And not every woman with a BRCA mutation will get breast cancer. There are many factors that can affect risk for hereditary or sporadic breast cancer.
For women with a BRCA mutation there is some evidence that the location and type of BRCA mutation can influence breast cancer risk but more research needs to be done to better understand the link between type of mutation and cancer risk.
Research has linked physical activity during the teen years, normal weight at menarche and at age 21with later onset of breast cancer in women with mutations. Exercise and a maintaining a healthy weight have other health benefits as well. Staying active is always a good idea. Visit our page on exercise for more information.
Research suggests that other genes can affect breast cancer risk in women with BRCA mutations.Two genes which have been associated with a slightly increase breast cancer risk in the general population may also be linked to breast cancer risk in BRCA carriers. Among the women who carried normal copies of these genes, the risk for breast cancer appeared to be at the lower end of the 50-85% breast cancer risk range. Of the BRCA-positive women who had two abnormal copies of these SNPs, lifetime risk for breast cancer was at the high end of the risk range. Women with one abnormal copy of the SNPs seemed to have a risk in the intermediate range.
Other factors can increase breast cancer risk in women without a mutation. Some of these factors also may have similar effects in women with mutations.
- previous breast biopsies (especially if the biopsy showed atypical cells or Lobular Carcinoma in Situ (LCIS)
- having dense breast tissue
- family history of breast cancer with or without a BRCA mutation
- young onset of menarche
- very high exposure to radiation
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