OBJECTIVES:

• Identify family characteristics, personality traits, and religious and spiritual beliefs that significantly affect individual decisions regarding mutation testing for hereditary nonpolyposis colon cancer (HNPCC) (recruitment of new families with HNPCC stopped as of 04-26-06, recruitment of persons within families already participating continues).
• Determine the impact of negative vs positive mutation test results on family relationships and psychological status.
• Assess expectations regarding testing and how they influence perceptions of risks and responses to risk notification.
• Determine the impact of risk notification on the frequency of screening/prevention activities.
• Formulate a standard diagnostic algorithm for determining microsatellite instability based on the analysis of tumors with this extensive array of markers and correlate specific replication error phenotypes with germline genotype.

OUTLINE: Participants complete a baseline assessment of knowledge, risk perception, and personality traits followed by a structured pretest education session. Participants are then offered the choice of whether or not to undergo genetic testing for mutations in hereditary nonpolyposis colon cancer (HNPCC) genes. Participants who choose to undergo genetic testing provide a blood sample for this purpose. Participants who undergo genetic testing receive results and counseling (recruitment of new families with HNPCC stopped as of 04-26-06, recruitment of persons within families already participating continues).

Available surveillance options are discussed for all participants. Psychological and behavioral outcomes are reassessed at 6 and 12 months for both those choosing and not choosing genetic testing.

Tumors (when available) are analyzed for mismatched repair deficiency on the basis of microsatellite instability.

PROJECTED ACCRUAL: A total of 900 participants will be accrued for this study, with a specific target of 200 individuals who have not experienced cancer within families identified with hereditary nonpolyposis colon cancer (HNPCC) mutations (recruitment of new families with HNPCC stopped as of 04-26-06, recruitment of persons within families already participating continues).