Ask the Expert: Is cancer hereditary?
Answer by Cristi Radford, Certified Genetic Counselor
The majority of cancers are not due to an inherited component. However, approximately, 5-10% of all cancers are “hereditary.” This means an individual develops cancer due to an altered gene present at birth. An individual can inherit the altered gene, also referred to as a mutation, from the mother or the father. It can be passed from grandparent to parent to child. The altered gene places an individual at an increased risk for certain cancers, not all cancers. For example, an individual with an alteration in BRCA1 is primarily at high risk of developing breast and/or ovarian cancer. As a man does not have ovaries, he cannot develop ovarian cancer. However, if the altered gene is passed to his daughters, they would be at increased risk of developing both breast and ovarian cancer.
Are there other genes besides BRCA1/2 associated with hereditary breast cancer?
Yes, that’s why it’s so important to have your personal and family history evaluated by an expert. BRCA1 and BRCA2 mutations account for the majority of hereditary breast and ovarian cancer families. However, breast cancer can also be linked to alterations in other genes, such as PTEN (Cowden’s syndrome), p53 (Li Fraumeni syndrome), STK11 (Peutz Jeghers syndrome), NF1 (Neurofibromatois type 1), CDH1 (Hereditary Diffuse Gastric Cancer), etc.. To date, over 200 hereditary cancer syndromes have been described.
Who should consider genetic counseling?
I like to use a 3, 2, 1 rule. If your mother’s family or father’s family has (don’t forget to include yourself, siblings, and children) ANY of the following, genetic counseling and possibly genetic testing may be useful:
· 3 or more individuals diagnosed with cancer
· 2 individuals diagnosed with cancer under the age of 50
· 1 individual with any of the following:
· multiple primary cancers
· diagnosed with breast, endometrial, or colon cancer under the age of 40
· less common cancer, such as ovarian cancer, male breast cancer, or medullary thyroid cancer
· Ashkenazi Jewish ancestry and breast cancer