When Hollywood star Angelina Jolie revealed in a New York Times op-ed that she chose to undergo a preventive double mastectomy to reduce her risk of getting cancer, the actress sparked a national dialog about genetic testing. Jolie carried a mutation of the BRCA1 gene, which sharply increases the risk of breast and ovarian cancer. Plus, she had a strong family history of both diseases. Her mother died of ovarian cancer at age 56; within two weeks of Jolie’s public revelation, her aunt (her mother’s sister) died of breast cancer at age 61.
Despite the publicity surrounding Jolie’s genetic cancer risk, genetic testing is not a one-size-fits-all approach to cancer screening, according to Michael Kosty, MD, medical director of cancer care at Scripps Clinic and Scripps Green Hospital. There is an increased prevalence of BRCA 1 and 2 in certain ethnic groups, such as Ashkenazi Jews. But in general, genetic mutations linked to cancer risk are rare in the general population. In fact, without a strong family history of cancer, genetic testing may create a false sense of security.
“Most cancers do not have a genetic basis,” says Dr. Kosty. “And even among many forms of cancer that are genetic in nature, we do not yet have tests that can positively identify all of the genes in play. You can’t just take a blood test and walk away assured that your personal cancer risk is minimal.”
Carrie Costantini, MD, a Scripps oncologist, agrees. “Genetic tests will not be useful for the whole population. They are most useful in conjunction with a strong family history of stomach, colon, lung, breast, ovarian or uterine cancers, and for some patients who have already been diagnosed with cancer relatively early in life,” she says.
Guidelines for genetic screening vary by tumor site. In general, a thorough and accurate family history is the strongest indicator of inherited cancer-causing genes.
“The most common cancer that can have a strong genetic component is breast cancer,” says Dr. Kosty. “Colon and prostate cancer also tend to run in families, but there’s no identifiable gene marker for those yet.”
When gathering information about your family’s cancer history, your physician may ask you the following:
- How many relatives had cancer, and what degree relative were they?
- First degree: Parent, sibling or child
- Second degree: Grandparent, aunt, uncle, niece or nephew
- What type of cancer (primary tumor site) did each relative have?
- How old were relatives at diagnosis?
“Accurate family histories can be tricky to get,” Dr. Kosty cautions. “Older relatives may say a great-aunt passed away from colon cancer, but in fact, that colon tumor might have been a metastasis of a primary breast tumor.” He suggests checking historical documents to confirm oral histories whenever that is feasible.
For people with significant family histories of cancer, there are pros and cons of testing for gene mutations that raise the risk of cancer.
- Potential peace of mind with negative result
- Opportunity to step up surveillance with positive results
- Ability to alert other family members, including children, of genetic status
- Stress may arise from knowing you carry a positive mutation
- Risks of preventive treatments may be serious themselves, and even a positive result does not guarantee cancer would ever develop in any individual
- Cost of genetic testing or preventive measure such as prophylactic surgery may not be covered by insurance
“In many cases, a positive test can help physicians and patients step up surveillance,” says Dr. Kosty. “Cancers that are genetic in nature are not necessarily more aggressive, invasive or fast growing. More frequent and detailed screening could still potentially catch the disease at the earliest, most treatable stage.”
“When a patient asks me whether to consider genetic screening for familial cancers, I always emphasize it’s a personal choice,” says Dr. Costantini. “Not everybody wants to know if they have a genetic predisposition to cancer. But in my experience, when people with a strong family history or personal diagnosis of early cancer do opt for testing, it’s an empowering decision.”