Who Should Have Genetic Testing for Hereditary Breast Cancer?

In cancer, there are 2 types of genetic tests :

1. To determine whether cancer is hereditary, tests analyze germline mutations as hereditary cancer tests, for example BRCA1 and 2 mutations. 
2. Gene tests analyzing somatic mutations that drive cancer and can be targeted with targeted drugs, for example EGFR, ALK, NTRK, BRAF and ROS1.

People outside oncology often confuse these two. Cancer being genetic does not mean it is hereditary; it means all cancers develop from DNA damage. Only approximately %5-10 of all cancers are hereditary, arising from certain mutated genes passed down from parents. Other cancers arise from somatic mutations, which are not inherited but develop after birth through exposure to various carcinogens during life.

- Related topic: Familial, Hereditary and Sporadic: Frequently Confused Concepts in Cancer

10 Percent of Breast Cancers Arise from Inherited Gene Mutations

Inherited gene mutationscan be detected by analyzing tissue and blood samples from the individual using genetic techniques. Genetic testsrequire an individual to meet certain criteria. They are interpreted jointly by a medical oncologist and a genetic counselor specializing in cancer genetics.

In Which Situations Should I Have Genetic Testing for Breast Cancer?

• If a mother, grandmother, sibling or maternal aunt developed breast cancer before age 50
• If there are cases of both ovarian and breast cancer on the mother’s or father’s side
• If someone in the family has triple-negative breast cancer
• If the family has prostate, skin, pancreatic, stomach, uterine, thyroid or colorectal cancer, or sarcoma, alongside breast cancer
• If any family member has had cancer in both breasts
• Ashkenazi Jewish ancestry
• If there is a man with breast cancer in the family
• If the same person has both breast and ovarian cancer
• If a gene mutation associated with hereditary breast cancer is known in the family

Genetic testing is recommended for individuals meeting any of the above conditions. An inherited gene mutation in a family does not mean every family member carries it.

Hereditary breast cancer genetic testing is not necessary for individuals who do not meet these criteria.

It is important to emphasize that carrying an inherited gene mutation associated with breast cancer does not mean a % 100 certainty of developing cancer, although these mutations substantially increase risk. Regular screening , risk-reducing surgical and medical measures, and lifestyle changes can significantly reduce breast cancer risk.

Which Hereditary Cancer Genes Are Associated with Breast Cancer?

For people with the risk factors listed above, testing the genes shown to be associated with hereditary breast cancer is recommended. If any test is positive, counseling should be sought from a medical oncologist and a clinical cancer genetics specialist.

ATM, BARD1, BRCA1, BRCA2, BRIP1, CHD1, CHEK1, CHEK2, MRE11A, MUYTH, NBN, NF1, PALB2, PTEN, RAD50, RAD51B, RAD51C, RAD51D, STK11, TP53

Hereditary breast cancers are discussed in our next article, How is risk managed in people with hereditary breast cancer syndrome? .

Note: For patients already diagnosed with early-stage breast cancer who have undergone breast cancer surgery, genetic testing to determine whether adjuvant (preventive) chemotherapy is needed is a separate issue. For these patients, the “priority” recommendation is not investigating hereditary cancer genes but tests analyzing certain somatic genes to determine tumor aggressiveness, such as Oncotype Dx Breast Recurrence Score . These tests aim to assess, after breast cancer surgery, the risk of cancer recurrence ; they are unrelated to hereditary breast cancers, and this recurrence test is not suitable for everyone who has had breast cancer surgery. You can read our detailed article on this topic here .

Related Topics

- Why did Angelina Jolie have both breasts removed?

- In nonhereditary breast cancer, surgery on the healthy opposite breast is unnecessary, costly and reduces quality of life