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 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 because of a greater awareness of the disease and more experience with multiple family members being affected.
Genetic testing for FAP is presently offered to children with affected parents, often at the age of 10 to 12 years, when endoscopic screening is recommended. Because it is optimal to diagnose FAP before age 18 years to prevent CRC and because screening and possibly surgery are warranted at the time an individual is identified as an APC mutation carrier, genetic testing of minors is justified in this instance. (Refer to the Testing in children section in the PDQ summary on Cancer Genetics Risk Assessment and Counseling for a more detailed discussion regarding the ethical, psychosocial, and genetic counseling issues related to genetic testing in children.)
In a survey conducted in the Netherlands of members of families with FAP, one-third (34%) believed that it was most suitable to offer APC gene testing to children before age 12 years, whereas 38% preferred to offer testing to children between the ages of 12 and 16 years, when children would be better able to understand the DNA testing process. Only 4% felt that children should not undergo DNA testing at all.