Families at risk for colorectal cancer - Risk assessment and genetic testing

As befits a common cancer, a family history of colorectal cancer (CRC) is r eported by about 10% of individuals. The discovery of the genetic basis of hereditary nonpolyposis CRC and familial adenomatous polyposis has opened u p the possibility for determining genetic predisposition to CRC in asymptom atic family members of affected cases. This article reviews the information needed for accurate risk assessment for those with a family history of CRC . Screenings recommendations and the current status of genetic testing, inc luding review of available tests such as microsatellite instability, immuno histochemistry for hMSH2 and hMLH1, testing for I1307K, and gene testing fo r germline mutations in hMSH2 and hMLH1 are discussed. At the current time, reliable, informative genetic testing, capable of application to broad seg ments of the population, is an unrealized goal. But as the methodology for testing improves and as better appreciation of the significance and meaning of a positive or negative test result ensues conditions for increased use of genetic testing could emerge.