How family history and genetics affect your cancer risk


by Baylor Scott & White Health

Oct 24, 2018

When a person receives a life-altering diagnosis like that of cancer, two questions generally asked are: “Am I going to die?” and “Will my family get this, too?”

The answer to the first question is long and complicated, and depends on a lot of things. But the answer to the second question is getting clearer all the time, all from a cheek swab or a blood test.

That’s because advances in genetic testing are making hereditary cancers easier to detect, and helping doctors and family members make better choices about prevention and treatment.

Understanding familial cancer vs. hereditary cancer

First, let’s distinguish between familial cancer and hereditary cancer. When cancer runs in a family, but without an identified genetic cause, this is known as familial cancer.

We label a cancer as “familial” when we believe there is a genetic mutation that contributes to the cancer seen within a family, but existing technology and available knowledge (including the impact of environmental and lifestyle factors) do not allow us to identify the genetic change that is causing it.

Hereditary cancer, on the other hand, is diagnosed when genetic testing identifies a “causative gene mutation”, or change in the gene related to the disease, that can be passed from one generation to the next and has the possibility to — but will not always — cause cancer.

Genetic mutations in hereditary cancers

Many people are familiar with genetic testing for breast cancer. People with a mutation in what is known as the BRCA gene, whether BRCA1 or BRCA2, are more likely than others to develop breast cancer, and at a younger age. Women who know they have this mutation usually get more frequent and intensive screenings and in some cases, undergo preventative mastectomies to remove their breasts and ensure they will never develop breast cancer.

That same BRCA gene mutation may increase your risk of ovarian cancer, pancreatic cancer, melanoma and cancers in the fallopian tubes or abdominal cavity, depending on which BRCA gene is damaged and where in the gene the damage occurred. In some cases, women will also have their ovaries removed based on the genetic findings in BRCA.

We also can use genetic testing to look for other hereditary cancers.

For example, Lynch Syndrome, historically referenced as a hereditary colon cancer syndrome, is also linked to other types of cancer. These include ovarian, pancreas, stomach, small bowel, bile duct, brain, certain kidney and urinary cancers, certain skin cancers and endometrial cancer. Again, like BRCA, this depends on which exact gene is involved, and where the mutation is located.

The importance of genetic testing

It’s important to remember that heredity cancer doesn’t impact every patient and family. But, the incidence of a hereditary predisposition for cancer is 1 in 10 cancer patients, far more than we ever estimated previously — and genetic testing is underutilized.

Regardless of the results, genetic testing can provide you, your family and your physician with useful information.

If results of genetic testing are negative, when applied with the right history both within the patient and his or her family, there can be great relief for people with cancer, knowing they are not passing the risk on.

But if they’re positive, it’s very useful for doctors to monitor family members for early detection, and to do screening earlier, more frequently and tailored with more sensitive testing methods.

Early detection screening is important for all people with either genetic or even lifestyle risk factors to consider, especially when there is risk for cancers that don’t have obvious symptoms, like pancreatic, ovarian or gastric cancer. But other tests and more advanced imaging may help detect a cancer at an earlier stage, meaning there is greater chance of survival and less chance of recurrence.

How to make the most of genetic testing

The field of genetic testing is exploding. Our technology and knowledge base is increasing so much that I believe there will be a day when it becomes routine, and you’ll carry a card with all that information.

But we’re not there yet. So, what should a patient do?

A cancer diagnosis can be overwhelming, and genetics may not be the first thing you think of. But it’s important for you to be your own advocate and ask your doctor what your genetic risk might be. You should also consider asking to be referred to a certified genetic counselor for testing and consultation. Likewise, if a family member has been diagnosed or there is a family history of cancer that may be a concern, ask your primary care provider for a genetic counseling referral.

Be wary of direct-to-consumer testing that is frequently advertised for both genealogy and hereditary risks. Many give false security and are not complete genetic tests. If there truly is a medical concern, it should be done by a lab with supervision.

Learn more about genetic testing or find a certified genetic counselor today.

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