Genetics of Colorectal Cancer (PDQ®): Genetics - Health Professional Information [NCI] - Psychosocial Issues in Hereditary Colon Cancer Syndromes
Table 16. Summary of Prospective Studies Evaluating Participation in Genetic Counseling and Testing for Hereditary Colorectal Cancer (CRC)a,b,c continued...
The majority of these studies that evaluated the uptake of genetic testing for LS have focused on genetic testing for MMR mutations associated with this syndrome. Few studies have examined uptake of MSI and IHC testing. One study reported low levels of knowledge and awareness of MSI testing among a sample of CRC patients who met the revised Bethesda guidelines for LS and were offered MSI testing. Patients in this study generally reported positive attitudes about the benefits of MSI testing; however, patients with higher levels of cancer-specific distress also perceived a greater number of barriers to having MSI testing.
Research is emerging on the usefulness of decision aids for LS genetic testing. One study showed that a decision aid, in booklet format, was effective in reducing uncertainty about the testing decision, assisting individuals to make an informed decision about testing, and improving testing knowledge among men. However, the decision aid did not appear to influence actual testing decisions. Another study evaluated the impact of an educational intervention in high-risk CRC patients prior to MSI and IHC testing but not MMR mutation testing. Patients who received a brief educational session delivered by a health educator plus a CD-ROM decision aid about MSI and IHC testing were found to have greater increases in knowledge about testing, higher satisfaction with preparation for decision-making about testing, lower decisional conflict, and greater decisional self-efficacy compared with patients who received only a brief educational session.
The uptake for genetic testing for FAP may be higher than testing for LS. A study of asymptomatic individuals in the United States at risk of FAP who were enrolled in a CRC registry and were offered genetic counseling found that 82% of adults and 95% of minors underwent genetic testing. Uptake rates close to 100% have been reported in the United Kingdom. A possible explanation for the greater uptake of APC genetic testing is that it may be more cost-effective than annual endoscopic screening  and can eliminate the burden of annual screening, which must often be initiated before puberty. The opportunity to eliminate worry about potential risk-reducing surgery is another possible benefit of genetic testing for FAP. The decision to have APC genetic testing may be viewed as a medical management decision; the potential psychosocial factors that may influence the testing decision are not as well studied for FAP as for other hereditary cancer syndromes.
The higher penetrance of APC mutations and earlier onset of disease also may influence the decision to undergo genetic testing for this condition, possibly due to a greater awareness of the disease and more experience with multiple family members being affected. Clinical observations suggest that children who have family members affected with FAP are very aware of the possibility of risk-reducing surgery, and focus on the test result as the factor that determines the need for such surgery. It is important to consider the timing of disclosure of genetic test results to children in regard to their age, developmental issues, and psychological concerns about FAP. Children who carry an FAP mutation have expressed concern regarding how they will be perceived by peers and might benefit from assistance in formulating an explanation for others that preserves self-esteem.