Explanations of Risk in Families Without Identified Mutations for Hereditary Nonpolyposis Colorectal Cancer

Conditions affecting multiple family members across generations are often said to “run in families” (Richards, 1996; Skirton & Eiser, 2003), and are experienced within the context of the family history of disease (McDaniel, Rolland, Feetham, & Miller, 2006a). Clinical practitioners, guided by the biomedical model, typically presume that these diseases are linked to inherited genetic mutations. However, at-risk individuals may have different thoughts about what causes the conditions in their families (Richards, 1996); even those who recognize certain health conditions as heritable may not use genetics-centered language to describe their risk. Lay beliefs can affect communication about risk and participation in risk-reducing behaviors (Feetham, Thomson, & Hinshaw, 2005; McDaniel, et al., 2006a; McDaniel, Rolland, Feetham, & Miller, 2006b). Assessing these beliefs could facilitate education, health promotion (Feetham, et al., 2005), and collaboration with health care providers (McDaniel, et al., 2006b). Families at risk for hereditary forms of cancer provide one context for examining beliefs about disease. Hereditary non-polyposis colorectal cancer (HNPCC) is an inherited cancer predisposition syndrome that increases risks for numerous cancers, the most prominent of which are colorectal (CRC) and endometrial cancers (Barrow, et al., 2009). At-risk individuals are identified through the Amsterdam criteria, which focus on clinical presentation and family history (Vasen & Boland, 2005), or assessment of molecular tumor characteristics, such as Microsatellite Instability (MSI). MSI is a classic pathological characteristic of HNPCC-associated colorectal tumors; its presence warrants testing for HNPCC mutations. Currently, four genes are known to be associated with HNPCC. Testing for a mutation is typically completed in an index case, an individual within the family who has had CRC and meets the Amsterdam criteria or whose tumor demonstrates MSI. Mutation identification allows targeted genetic testing of at-risk family members to clarify disease risk and guide clinical management (Lindor, et al., 2006). An associated mutation is identified in 50–80% of index cases meeting HNPCC criteria; however, 20–50% receive indeterminate genetic test results, in which no change in DNA sequence is detected (EGAPP Working Group, 2009; Vasen & Boland, 2005). This precludes targeted genetic testing of other family members. Genetic advances will likely identify additional HNPCC candidate genes; more extensive testing may eventually pinpoint a genetic cause for the cancers in these families. Until then, family members of index cases who received indeterminate genetic test results must remain vigilant in cancer screening. Individuals at risk for developing the cancers associated with HNPCC are encouraged to participate in intensive screening protocols (Lindor, et al., 2006). This includes: individuals known to carry an HNPCC-associated mutation; biological family members of mutation-positive index cases who choose not to have genetic testing; and members of families meeting clinical and pathological criteria for HNPCC in which no causative mutation has been identified. Beginning in young adulthood, colonoscopy every 1–2 years facilitates early identification of CRC, or prevents CRC through identification and removal of colorectal polyps. Colonoscopy use reduces the incidence of CRC and improves survival (Jarvinen, et al., 2000). This study focused on CRC and not the other cancers for which HNPCC increases risk due to established screening recommendations (Lindor, et al., 2006) with clear benefits for CRC detection and survival (Jarvinen, et al., 2000). Lay explanations of hereditary conditions provide insights into an individual’s understanding of the condition and beliefs about risk. The family and social context influence how individuals make sense of their own and others’ risks for inherited conditions (Cox & McKellin, 1999; McAllister, 2003; Skirton & Eiser, 2003). In families with HNPCC mutations, lay models are grounded in personal experiences and interpretations of the family history (McAllister, 2003). Families with indeterminate HNPCC genetic test results provide a unique opportunity to examine interpretations of risk, because widespread genetic education, counseling, and testing do not typically occur within such families. This study explored thoughts about and response to risk for HNPCC in the context of indeterminate genetic test results.