With regard to genetic testing for hereditary nonpolyposis colon cancer (HNPCC) the ICSI Technology Assessment Committee finds:
Genetic testing of HNPCC can reduce the number of surveillance colonoscopies and help target surveillance at high-risk patients (Conclusion Grade II), however, studies of the effect of genetic testing of HNPCC on more substantial outcomes such as mortality are limited. Further studies are needed to determine more substantial medical benefits of genetic testing for HNPCC.
Genetic testing requires pre- and post-test genetic counseling and written informed consent for both affected and at-risk individuals. Individuals who appear to be at-risk for HNPCC should be referred to a center with expertise in cancer genetics. Laboratory testing should be done by a reliable reference laboratory with experience in MSI, IHC, and germline testing. Genetic testing in HNPCC is acceptably safe when these criteria are met.
Criteria exist (see Potential Uses) to help determine who should be tested. Testing is not indicated for patients with sporadic colorectal cancer or family members of patients with sporadic colorectal cancer. Testing is also not indicated for mass screening of the general population.
If germline mutation analysis indicates a deleterious mutation, genetic testing of at-risk family members can provide true positive and negative results. If no deleterious mutation is found in the affected person, genetic testing of at-risk family members will only provide inconclusive results.