Genetic testing, like most medical procedures, has its associated benefits and risks. On the one hand, a predictive gene test can help determine a patient’s risk of future cancer. Therefore, individuals who test positive for genes associated with cancer can be monitored closely for early detection and treatment of a disease.

In other cases, patients who test positive may be urged to take preventative measures that can lower the risk of future cancers. For example, women who test positive for the genetic mutations BRCA1 or BRCA2 are at high risk for developing breast cancer. Some patients may choose to have a mastectomy (called a prophylactic mastectomy) to reduce their risk of developing breast cancer. 

With genetic testing, there is also the risk that individuals with negative test results may adopt a false sense of security, as seen with breast cancer.  Most breast cancers occur in women who would test negative for breast cancer mutations.

These tests also fail to reveal the exact type or severity of cancer that may develop and how it will progress. In addition, technical or human errors can skew testing results, and some tests will be inconclusive even when properly performed. In a recent study conducted on commercial genetic testing, the American Cancer Society reported that up to 12 percent of people who tested negative for BRCA1 and BRCA2 gene mutations may have had dangerous alterations in those genes. According to ACS, a woman with no BRCA mutations has about a 13 percent lifetime risk of breast cancer. In contrast, a woman with a mutation has an 80 percent lifetime risk of developing breast cancer. For this reason, it is important that genetic testing be as accurate as possible.

Although patients can often benefit from genetic testing, these diagnostic tools do raise social, ethical and legal concerns that they should consider before choosing to be tested. Genetic testing does not necessarily tell patients whether or not they (or their children) will develop cancer or other diseases. Negative results do not ensure that the patient will never develop cancer, and positive results do not indicate when cancer is likely to occur, if it occurs at all.