Breast Cancer: Genetic Testing for Inherited Mutations

This section covers the following topics:

People with breast cancer should talk with their doctor about genetic testing.

Breast cancer survivors and those in treatment should speak with a genetics expert to decide if genetic testing is right for them. About 10% of people diagnosed with breast cancer have an inherited mutation that caused their cancer.

Genetic test results may affect your cancer treatment.

• People with breast cancer who have an inherited mutation may have different treatment options than people without a mutation.  

Genetic test results may help you and your relatives understand the risk for cancer and take action to stay healthy.

• If you test positive for an inherited mutation, you may have an increased risk for other cancers.
• Expert guidelines outline cancer screening and prevention options for people at high risk for cancer due to an inherited mutation.   

Genetic testing guidelines for people diagnosed with breast cancer

Experts recommend genetic counseling and testing if you have breast cancer and any of the following applies to you:

• triple-negative breast cancer.
• diagnosed with breast cancer more than once. 
• breast cancer diagnosed at age 50 or younger.
• male breast cancer or assigned male at birth.
• advanced or metastatic breast cancer.
• early stage breast cancer and at high risk for recurrence to learn if there would be benefit to treatment with a PARP inhibitor.
• a close blood relative (first-, second- or third-degree) who tested positive for an inherited mutation in a gene linked to cancer risk.
• a close blood relative diagnosed with male breast cancer. 
• Ashkenazi Jewish ancestry.
• lobular carcinoma and a personal or family history of diffuse gastric cancer.

Experts also recommend genetic counseling and testing for people diagnosed with breast cancer at age 50 or older with any of the following:

• a close relative with breast cancer at age 50 or younger.
• a close relative with male breast, ovarian or pancreatic cancer.   
• a close relative with prostate cancer that is metastatic or high-risk or very high-risk group. 
• three or more close relatives on the same side of the family with either breast or prostate cancer (including the patient). 

If you had genetic testing in the past and tested negative, you may benefit from additional testing:

• if you had a test that only looked for one or a few genes, or 
• if you had genetic testing before 2014. Genetic testing has improved, and laboratories can now find gene mutations that may have previously been missed.

Relatives of people who have been diagnosed with breast cancer may also benefit from testing.

Genetic counseling and testing is also recommended for anyone with one or more 1st- or 2nd-degree relatives with breast cancer and any of the following:

• diagnosed at age 50 or younger
• triple-negative breast cancer
• two separate breast cancers, with the first diagnosis at age 50 or younger
• male breast cancer

Genes linked to breast cancer in women

Mutations in the following genes have been linked to increased risk for breast cancer in women and people assigned female at birth.

Genes linked to male breast cancer

Mutations in the following genes have been linked to breast cancer in men and people assigned male at birth.

Breast cancer subtypes associated with inherited gene mutations

Some inherited mutations have been linked to certain types of breast cancer. 

• People with inherited BRCA1 mutations are more likely to develop triple-negative breast cancer than any other subtype of breast cancer. 

• People with CDH1 mutations are more likely to develop lobular carcinoma than ductal carcinoma. 

• People with NF1 mutations are more likely to develop HER2-positive breast cancer.