Genetic testing has many clinical uses. With regard to cancer, it looks for certain changes (mutations) in a person’s genes that might increase his or her risk of developing certain cancers. Genetic testing can be offered to individuals with a strong family history or personal history of cancer. If a genetic mutation is found, this can have several implications.
For instance, mutations in the BRCA gene can increase the risk of developing breast and ovarian cancer. It is recommended that women with known BRCA mutations start breast cancer screenings at a younger age than the general population — late 20s versus age 40. In addition, MRIs are used in addition to mammograms for screening purposes. Further, measures to reduce the risk of developing breast cancer, such as medication or surgical intervention, also may be considered.
Another example is Lynch syndrome, which increases the risk of young-onset colon cancer, uterine cancer and several other cancers. Currently, the recommendation for the general population is to start colon cancer screening at age 45, and if the screen is normal to have a colonoscopy every 10 years. With Lynch syndrome however, colon cancer can develop at a young age and grow very quickly; thus for Lynch syndrome patients, the recommendation is to start screening in the 20s and repeat at 12- to 18-month intervals.
Most people (even people with cancer) do not need this type of testing. Only about 5-10 percent of cancers are related to inherited genetics. Genetic testing should be considered for individuals who have had certain cancers or patterns of cancer in their families, such as one or more first- or second-degree relatives with:
- cancer before age 50
- the same type of cancer
- two or more different cancers in an individual
- a rare cancer, such as male breast cancer
- a known familial mutation, such as BRCA 1 or BRCA 2
- a certain race or ethnicity (such as Ashkenazi Jewish ancestry)
- abnormal physical finding, such as many colon polyps, known to be linked to inherited cancer
- certain cancer patterns in the family, such as breast, pancreatic or prostate, might suggest BRCA mutation
If you are concerned about cancer history in your family or your own personal history of cancer, talk to your health provider to determine whether you should be tested.
