Knowing precisely why some people develop cancer and others don’t can be puzzling. Genetics and gene mutation are only two pieces of this jigsaw, but they can be instrumental in determining if someone is at an increased risk for various kinds of cancer. Anna Villa, MS, CGC, genetics counselor, Parkview Cancer Institute, helps explain gene mutations, how they develop and who should consider genetic testing for hereditary cancer syndromes.

What percentage of cancers are heredity?

If we consider all cancer types, about 10% are hereditary. However, some cancer types are more genetic than others. For example, nearly 10% of breast cancers are hereditary, but that number increases to almost 20% for pancreatic and ovarian cancers.

What is a gene mutation?

Think of genes as recipes that the body uses to create what it needs. When we test for hereditary cancer syndromes, we examine the genes responsible for telling our bodies how to protect themselves against cancers. A mutation in a gene means that the recipe is incorrect. Maybe it has missing ingredients or instructions. Perhaps the recipe tells you to add too much of one element. Or maybe the recipe is a jumbled mix of letters that we can’t read. No matter, a gene mutation is an error in the recipe that our bodies utilize for cancer protection.

Are people born with gene mutations, or do they develop over time?

When we talk about hereditary cancer syndromes, we mean the gene mutations at birth (usually present at conception). While gene mutations can develop over time, those mutations are not typically inherited. Those mutations are present only in cancer cells, not passed on to future generations.

What types of cancer are caused by BRCA gene mutations?

Mutations in the BRCA genes increase an individual’s risk for breast cancer (in both males and females), ovarian cancer, prostate cancer, pancreatic cancer and melanoma. However, it is important to acknowledge that other genes can also increase a person’s risk for these types of cancers. If someone considers genetic testing, it is essential to evaluate all genes known to have associations with the cancer types seen in their personal and family history.

Does the mother primarily pass on the BRCA genetic mutation?

Gender is not a factor in whether someone inherits or passes on a BRCA gene mutation. Both males and females have the same risk of inheriting a BRCA mutation and passing it to the next generation.

And, while it’s true that females with BRCA mutations tend to have higher cancer risks than males with BRCA mutations, both have an above-average risk for cancers. Therefore, men and women with BRCA mutations will likely need extra cancer screenings and interventions, beginning at younger ages than individuals at average risk for cancer.

Do all BRCA mutations result in a person developing cancer?

Having a BRCA mutation does not guarantee an individual will develop cancer. However, it does mean that they are at an above-average risk for certain cancer types. For example, the average lifetime risk for a woman to develop breast cancer is about 12%. If a woman has a BRCA mutation, that risk increases to about 70%. So, the risk for breast cancer (and other cancers) is undoubtedly higher for individuals with BRCA mutations, but it’s still not a guarantee of cancer. It’s also important to note that mutations in other genes, not just BRCA, can increase an individual’s risk for cancers. The extent to which these gene mutations increase cancer risk can be quite variable. They can be anywhere between a 20-70% lifetime risk for breast cancer.

Who should get tested for genetic mutations?

It’s important to test individuals who have a personal history of cancer. However, this isn’t always possible, so people with personal or family histories of the following should consider genetic testing for hereditary cancer syndromes:

• A known gene mutation in a family member
• Specific cancer types such as ovarian cancer, pancreatic cancer, metastatic prostate cancer, metastatic breast cancer, triple-negative breast cancer or male breast cancer
• Breast, colon or uterine cancers diagnosed before age 50
• A combination of three or more breast and/or prostate cancers on the same side of the family

If someone is concerned about hereditary cancer risk and doesn’t meet the above criteria, they can still consider genetic testing. Many labs now offer self-pay options for individuals who don’t meet the standard.