Table 16. Summary of Prospective Studies Evaluating Participation in Genetic Counseling and Testing for Hereditary Colorectal Cancer (CRC)a,b,c continued...
Participation in both pretest genetic counseling and posttest counseling for disclosure of results ranged from 14% to 59% across studies (Table 16). The wide range of uptake rates suggests that factors such as cost, test characteristics, and the context in which counseling and testing were offered may have influenced participants' decisions. For example, among studies that offered free genetic counseling and testing in the context of a research protocol, counseling uptake ranged from 21% to 59% and testing uptake ranged from 36% to 59%.[10,39,40,41,43,44,45] The majority of those who had participated in a free pretest counseling or education session almost always followed through with genetic testing. Further research is needed to evaluate LS genetic counseling and testing participation in the clinical setting.
Although limited in number, these studies offer insight into why individuals from families at risk of LS decide to undergo or decline genetic counseling and testing. Participation in LS genetic counseling was associated with having children, having a greater number of relatives affected by CRC, and greater social support. A study of CRC patients who had donated a blood sample for genetic testing also showed that those who intended to follow through with receiving results were more worried that they carried a LS-predisposing gene mutation, believed that testing would help family members, and more strongly endorsed the benefits and importance of having testing. Factors associated with both counseling and testing uptake included having: children, a greater number of affected relatives, a greater perceived risk of developing CRC, and more frequent thoughts about CRC.[39,40,41,43,44,45,48]
Less is known about the characteristics of persons who decide to not undergo LS genetic counseling and testing. Studies have found that persons who declined counseling and testing reported to have a lower perceived risk of CRC, to have fewer first-degree relatives affected with cancer, to be less likely to have had a previous colonoscopy, to have a college education, to have previously participated in cancer genetics research, or to be employed. Psychological factors also may limit the uptake of genetic counseling and testing. Those who declined counseling and testing, especially women, reported lower perceived ability to cope with mutation-positive test results, and were more likely to report having depressive symptoms. Reasons cited for not seeking genetic counseling or testing have included concerns about potential insurance discrimination, how genetic testing would affect one's family, and how one would emotionally handle genetic test results.
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.