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The two genes most commonly associated with hereditary breast and ovarian cancer are called BRCA1 and BRCA2 (for Breast Cancer 1 and Breast Cancer 2 genes). Inherited mutations in these genes increase the risk for these cancers: ovarian cancer in women, prostate cancer in men, and breast, melanoma, and pancreatic cancer in both men and women.
Breast Cancer in Women
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.
Different research involving many families with
BRCA mutations showed a 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 BRCA1 mutation carriers and 56% in BRCA2 mutation carriers.
Different studies on ovarian cancer risk in different populations have revealed different risk estimates. One study combined results from many smaller research studies to determine an average risk for ovarian cancer. This "meta-analysis" determined the average lifetime risk to be 55% in
BRCA1 mutation carriers and 31% in BRCA2 mutation carriers. These are the risk numbers experts often use for cancer risk in mutation carriers.
Another study that looked at women with one of the
BRCA1 or BRCA2 mutations common in Jewish populations indicated a lifetime ovarian cancer risk of 54% in women with BRCA1 mutations and 23% in women with BRCA2 mutations. A different study of multiple families with BRCA mutations (not specifically Jewish families) found a comparatively lower risk: 39% for BRCA1 carriers, compared to 11% of BRCA2 carriers by age 70.
All the studies show the risk for ovarian cancer in
BRCA carriers begins after age 30, and most of the risk occurs after age 40 for BRCA1 mutation carriers and age 50 for BRCA2 mutation carriers.
Breast Cancer in Men
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).
BRCA mutations have a 15-25% lifetime risk for prostate cancer, which is much higher than average-risk men. In men with BRCA mutations, prostate cancers tend to occur at a younger age and may be more aggressive and life threatening than prostate cancer in men without mutations. Men with BRCA2 mutations are at higher risk than men with BRCA1 mutations.
The risk for
BRCA carriers is up to 5% compared to 1.5% in the general population. The risk is higher for BRCA2 mutation carriers than individuals with BRCA1 mutations.