Hereditary Breast and Ovarian Cancer
Considering Genetic Testing for Breast and Ovarian Cancers
Identifying whether you have an abnormal gene related to breast cancer could help predict what other cancers you might be at risk for, including ovarian cancer. Knowing this information allows your health care providers to recommend strategies to prevent or detect those cancers at an earlier stage. And, if you've been diagnosed with breast or ovarian cancer, knowing your genetic status might alter the treatment plan for you.
BRCA Genes
In 10 percent of breast cancer cases, the cancer is caused by an abnormal gene mutation from one of the parents. The most common genes that cause breast cancer are known as BRCA1 and BRCA2. In families where one parent carries one of the genes, there is often at least one woman — most often, more — who has developed breast cancer before she turned 50. Another clue that a BRCA1 or BRCA2 abnormality exists is the presences of ovarian cancer, male breast cancer, or breast cancer in both breasts.
The mutated gene can be found in any family with the appropriate cancer history, although these mutations are more prevalent in Ashkenazi Jewish families. In Jewish families, genetic testing should be considered for any woman who has two close relatives diagnosed with breast cancer before age 65, or any instance of ovarian cancer.
Hereditary Breast and Ovarian Cancer Syndrome
Hereditary Breast and Ovarian Cancer Syndrome (HBOC) is a hereditary cancer syndrome caused by mutations in the BRCA1 and BRCA2 genes. HBOC is associated with a significantly increased risk to develop breast and ovarian cancer, and a smaller increased risk to develop other types of cancer such as melanoma, pancreatic cancer, male breast cancer and prostate cancer.
BRCA1/2 mutations are inherited in an autosomal dominant pattern. Both men and women can carry BRCA gene mutations and can pass them down to their children. An individual with HBOC has a 50 percent chance of passing the genetic mutation causing HBOC to children.
For women and men with HBOC,
- Women have up to an 87 percent lifetime chance to develop breast cancer.
- Women have up to a 64 percent chance to develop ovarian cancer.
- Men have up to a seven percent lifetime risk to develop male breast cancer.
- Men have up to a 39 percent risk to develop prostate cancer.
- Men and women both have approximately a five to seven percent lifetime risk to develop pancreatic cancer and melanoma.
Genetic testing for the BRCA genes can help you and your healthcare team make important decisions regarding your medical management. There are many cancer screening and prevention options for individuals who have an elevated risk to develop cancer, including vigilant cancer screening, medications to lower cancer risk and preventative surgery (removing healthy tissue before cancer develops).
Other Hereditary Breast Cancer Genes
About 50 percent of hereditary breast cancer is unrelated to known mutations in BRCA1 or BRCA2. Newly available testing technology called “next generation sequencing” allows testing of many genes associated with breast and ovarian cancer at the same time. The results of next generation sequencing may or may not immediately change an individual’s medical management, though they may impact future cancer screening for that individual as well as their family members.
Other, more rare, hereditary cancer syndromes associated with increased risk to develop breast cancer include:
- Li Fraumeni Syndrome, caused by mutations in the TP53 gene
- Cowden Syndrome (or PTEN hamartoma tumor syndrome), caused by mutations in the PTEN gene
- Hereditary Diffuse Gastric Cancer (HDGC), caused by mutations in the CDH1 gene