Approximately 1 in 8 women will develop a breast cancer in their lifetime. As many as 5-10% of all breast cancer is thought to be due to an inherited genetic mutation. Thanks to advances in genetic testing, we now know that there are many genes associated with an increased risk for breast cancer. These genes include but are not limited to ATM, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, MRE11A, MUTYH, NBN, NF1, PALB2, PTEN, RAD50, RAD51C, RAD51D, and TP53.
The most common causes of Hereditary Breast and Ovarian Cancer (HBOC) Syndrome are caused by mutations in the BRCA1 and BRCA2 genes. A woman with an inherited BRCA1 or BRCA2 mutation has a 50-85% chance of developing breast cancer over her lifetime, compared to a 12% risk in the average woman. For women who have had breast cancer, the chances of a second breast cancer in either the same or the opposite breast is 40-60%. Another way to think about this risk is approximately 1-1.5% per year. This means that while the overall chances of developing cancer are high, the risk is spread out over many years, and women can take some time to consider the options for cancer monitoring and prevention that are best for them. Men with mutations in BRCA1 or BRCA2 have a 5-10% chance of developing male breast cancer, compared to a risk of about 1/1000 in the general population.
Approximately 15% of all ovarian cancers are thought to be caused by an inherited genetic mutation. National guidelines recommend that anyone with ovarian cancer undergo genetic testing regardless of age of diagnosis. Thanks to advances in genetic testing we now know that there are many genes associated with an increased risk for ovarian cancer. These genes include but are not limited to BRCA1, BRCA2, MLH1, MSH2, MSH6, PMS2, TP53, PALB2, BRIP1, RAD51C and RAD51D and STK11.
The most common causes of Hereditary Breast and Ovarian Cancer (HBOC) Syndrome is caused by mutations in the BRCA1 and BRCA2 genes. A woman who has a mutation in BRCA1 has a 40% chance of developing ovarian cancer in her lifetime. The chances of developing ovarian cancer with a BRCA2 mutation are somewhat lower, approximately 20%, compared to a 1-2% risk of ovarian cancer in the general population. Cancers of the fallopian tube and peritoneum (lining of the abdominal cavity) are also seen more frequently in people with BRCA1 and BRCA2 mutations.
The good news is that there are things that can be done to lower one's risk of breast and ovarian cancer if she is found to be at an increased risk. To learn about screening for hereditary breast cancer, visit our Prevention and Surveillance page.