Genetic Risks

What are your genetic risk factors for developing breast cancer?

About five to 10 percent of breast cancers are thought to be hereditary, caused by abnormal genes passed from parent to child.

Most inherited cases of breast cancer are associated with two abnormal genes: BRCA1 (breast cancer gene one) and BRCA2 (breast cancer gene two). Less common genes involved with hereditary breast cancer are PTEN, p53, CHK2, PALB2.

Everyone has these genes. The function of the BRCA genes is to repair cell damage and keep breast cells growing normally. But when these genes contain abnormalities or mutations that are passed from generation to generation, the genes don't function normally and breast cancer risk increases. Abnormal BRCA1 and BRCA2 genes may account for up to 10 percent of all breast cancers, or one out of every 10 cases.

Having an abnormal BRCA1 or BRCA2 gene doesn't mean you will be diagnosed with breast cancer. Additional mutations must occur during one’s lifetime for breast cancer to develop even in a BRCA carrier but the risk is higher and onset earlier since a patient is already born with one abnormally functioning gene. Other mutations in areas of your chromosomes – called Single Nucleotide Polymorphisms, or SNPs – may be linked to higher breast cancer risk regardless of BRCA status, and testing is available at the Breast Center to evaluate for these SNP’s.

Women who are diagnosed with breast cancer and have an abnormal BRCA1 or BRCA2 gene often have a family history of breast cancer, ovarian cancer, and other cancers. It should be noted that most breast cancers are not from an abnormal breast cancer gene.

You are substantially more likely to have an abnormal breast cancer gene if:

  • You have female blood relatives on either your mother or father's side of the family who had breast cancer diagnosed before age 50.
  • There is both breast and ovarian cancer in your family, particularly in a single individual.
  • There are other gland-related cancers in your family such as pancreatic, colon, and thyroid cancers.
  • Women in your family have had cancer in both breasts.
  • You are of Ashkenazi Jewish (Eastern European) heritage.
  • You have been diagnosed with breast cancer before age 45.
  • You have been diagnosed with a triple negative breast cancer and you are younger than 60.
  • A man in your family has had breast cancer.
  • If one family member has an abnormal breast cancer gene (Note:  there is a 50:50 chance of an individual inheriting the faulty gene from a parent).

Women who have an abnormal BRCA1 or BRCA2 gene (or both) can have up to an 80% risk of being diagnosed with a first breast cancer and a 40-60 percent chance of getting a second breast cancer during their lifetime. Breast cancers associated with an abnormal BRCA1 or BRCA2 gene tend to present at a younger age compared to women without these abnormal genes.

Women with an abnormal BRCA1 or BRCA2 gene also have an increased risk of developing ovarian, pancreatic, melanoma and possibly colon cancer.

Men and the BRCA1 and BRCA2 genes

Men who have an abnormal BRCA2 gene have a higher risk for breast cancer than men who don't, nearly eight percent by the time they're 80 years old. This is about 80 times greater than average.

Take our Hereditary Cancer Quiz

The above calculator is intended only as a guideline. Please see your Providence Saint John’s Margie Petersen Breast Center surgeon or cancer-risk assessment and prevention physician to determine your risk of developing breast cancer by selecting from the list of our providers.