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...
In contrast to the LS genetic counseling and testing uptake studies that have been conducted in the United States, findings from similar studies conducted in other countries may differ. A Finnish study found that 75% of individuals at risk of developing LS underwent genetic testing and counseling for disclosure of test results. Being employed was the only factor that independently predicted test uptake. Fundamental differences between U.S. and Finnish health care systems may have accounted for the substantial differences in testing uptake in this study compared with similar ones conducted in the United States. In particular, the lower likelihood of health or life insurance discrimination in a European state such as Finland may have eliminated an important barrier to testing in that setting.
The majority of these studies that evaluated the uptake of genetic testing for LS have focused on genetic testing for mismatch repair (MMR) mutations associated with this syndrome. Few studies have examined uptake of microsatellite instability (MSI) and immunohistochemical (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 before 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.