Early detection is critical when it comes to cancer. Genetic counseling and testing can help in some cases.
In some cases, cancer is caused by a gene variant or mutation that has been passed from generation to generation. The National Cancer Institute estimates that inherited gene variants contribute 5 to 10 percent of all cancers.
Fortunately, genetic testing can determine if someone is at higher risk for developing certain types of cancer that tend to be hereditary.
The US Preventive Services Task Force recommends a risk assessment for women with a personal or family history of breast, ovarian, tubal or peritoneal cancer or an ancestry associated with a gene variant that increases the risk of developing these cancers.
The genes most commonly affected in hereditary breast and ovarian cancer are the breast cancer 1 (BRCA1) and breast cancer 2 (BRCA2) genes.
At Scripps, a physician referral is required to meet with a genetic counselor to discuss genetic disorders and testing.
A physician may recommend genetic counseling if you are in one of these two groups:
Group one includes people who are cancer-free but may be at higher risk due to medical conditions or family history. This includes people with:
- Two or more family members with the same type of cancer
- The same or related type of cancer in several generations of a family
- Ashkenazi (Eastern or Central European) Jewish ancestry and family history of breast, ovarian, prostrate or pancreatic cancer
- Polyposis or multiple polyps in the stomach or intestines
Group two includes people who have cancer and want to know if it is hereditary. This includes patients who:
- Developed cancer at an earlier age than usual for their disease
- Have been diagnosed with two or more separate cancers
- Developed a rare type of cancer, such as male breast cancer
- Have a family history of the same or related type of cancer
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.
Genetic counselors provide information and guidance about genetic disorders, genetic testing, interpret test results and advice families about their options. They are trained in medical genetics and counseling.
A genetic counselor will perform a risk assessment based on your personal and family medical history.
Common questions during the review include:
- How many relatives had cancer?
- Were they a first degree relative: Parent, sibling or child?
- Were they second degree: Grandparent, aunt, uncle, niece or nephew?
- What type of cancer 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 recommends checking historical documents to confirm oral histories whenever feasible.
If you decide to have genetic testing, the counselor will discuss which family member is the best candidate for testing. Usually, this will be someone who has cancer.
Testing is usually done with a blood sample. Sometimes saliva, cells from inside the cheek or skin cells are used. It takes one to three weeks for the lab to analyze your sample.
Genetic testing results become part of your medical record and are shared with your health care providers.
For people with significant family histories of cancer, testing is an option that should carefully be considered.
- Potential peace of mind with negative result
- Opportunity to step up surveillance with positive results
- Ability to alert other family members, including children, about genetic status
- Stress may arise from knowing you carry a positive mutation.
- Risks of preventive treatments may be serious themselves. Even a positive result does not guarantee cancer would ever develop in any individual.
- Cost of genetic testing or preventive measure, such as 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.”
Despite the attention genetic testing has received in recent years, it is not a one-size-fits-all approach to cancer screening.
“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,” says Dr. Kosty.
“Most cancers do not have a genetic basis,” he adds. “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, says genetic tests are useful for very specific populations, but the decision to get one is a personal choice.
“They are most useful when there is a strong family history of stomach, colon, lung, breast, ovarian or uterine cancers, and for some patients who were diagnosed with cancer relatively early in life,” Dr. Costantini says.
“Still, when a patient asks me whether to consider genetic screening for familial cancers, I always emphasize it’s a personal choice.
“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.”