Inherited genetic mutations cause an estimated five to 10 percent of cancers.
In the past, genetic testing was focused on individuals already diagnosed with cancer. For many years women with breast cancer have been tested for mutations in the BRCA1 or BRCA2 genes and men and women with colon cancer have had genetic testing to determine if their cancer was caused by Lynch syndrome.
Now, genetic testing is becoming more widely available to individuals who want to be proactive and better understand their risks in order to prevent cancer.
If we know that a woman has a higher chance to have breast cancer she can begin breast cancer screening at an earlier age and include both mammograms and breast MRIs into her plan. A woman or man who has a higher chance to develop colon cancer could begin colonoscopies at an earlier age and continue to have them more frequently than other people without a mutation.
Individuals who should consider proactive genetic testing include those who have multiple family members diagnosed with breast, ovarian, uterine or colon cancer, especially if any family members were diagnosed under age 50.
This includes individuals with a person in their family diagnosed with more than one type of cancer, called multiple primary tumors. It's important for patients to gather information about both sides of their family because hereditary cancer predisposition genes are inherited from both parents, even in the case of female cancers, such as breast or ovarian cancer.
Those with a strong family history of cancer should begin talking with their physician about genetic counseling and testing in their 20s, or at about the same age as screening for that cancer would be recommended.
Genetic testing is conducted on a blood or saliva sample. New technology has allowed us to test for mutations in many genes associated with a moderate to high chance of developing cancer. Following genetic testing, patients receive their results from a genetic counselor and are then referred to the appropriate physician(s) for follow up discussion, screenings, etc.