Psychosocial Issues in Hereditary Colon Cancer Syndromes: Lynch Syndrome and Familial Adenomatous Polyposis
Participants in these studies were drawn from the general population and were not selected for known CRC risk factors; their interest in genetic testing was based on answers to largely hypothetical questions. Some findings indicate that interest in genetic testing may be high in the general population; however, the apparent interest may be due in part to a lack of awareness about the risks and limitations of testing or the view that genetic testing is similar to other more routine medical tests. Although these studies may help assess interest in genetic testing in the general population, it is possible that they overestimate the actual demand for such services.[5,6]
Interest in genetic counseling and testing among CRC patients and their close relatives
Studies of CRC patients and their unaffected relatives showed varying levels of interest in or intention to undergo hereditary CRC genetic testing (Tables 13A and 13B). Participants in these studies were recruited through tumor registries or familial colon cancer registries,[7,8,9,10] oncology treatment centers,[11,12,13,14] and the community.[9,12,13,14] Study outcomes were reported as either testing interest or testing intention. Participants were not necessarily selected based on features that are characteristic of a hereditary CRC syndrome. Thus, when asking about intention or interest in genetic testing, most studies referred to testing in a general manner (e.g., testing for a hereditary colon cancer gene) rather than asking about testing for specific syndromes such as LS (also called hereditary nonpolyposis colorectal cancer [HNPCC]) or FAP. Some factors that were not consistently addressed in all studies (e.g., cost, test accuracy, or assuming that other relatives were gene mutationcarriers) may account for some of the variability in findings regarding testing interest or intention.
Table 13A. Summary of Studies Evaluating Interest in or Intention to Have Genetic Counseling and Testing for Familial Colorectal Cancer (CRC)a
FDR = first-degree relative; GC = genetic counseling; GT = genetic testing; HCCR = hereditary colon cancer registry.
a All studies used a cross-sectional design, with the exception of one study, which used focus groups. All studies were conducted in the United States, with the exception of one Canadian study.
b Indicates number of participants older than 18 y, unless otherwise specified.
c Type of genetic test not specified.
d Random Digit Dial Survey with general population samples.
e Unaffected = no previous diagnosis of CRC.
|Study Population||Nb||Interest or Intention in GC or GTc|
|General population (Utah), RDDSd||401||47% very interested in GT; 35% somewhat interested in GT|
|General population (Utah), RDDS ||383||47% very interested in GT; 37% somewhat interested in GT|
|Unaffectede FDRs of CRC patients from tumor registry ||426||46% GC intention; 26% definite GT intention|
|Unaffected FDRs of CRC patients from HCCR ||1,373||77% definite GT intention if free; 15% probable|
|CRC patients from an oncology center and community ||98||52% definite GT interest; 20% probable|
|Unaffected FDRs of CRC patients from an oncology center and community ||95||84% GT interest|
|Focus groups of CRC patients and unaffected FDRs from an oncology center and community ||28 CRCs ||CRCs: 96% GT interest before group; 89% after group|
|33 FDRs||FDRs: 82% before group; 42% after group|
|General population (Ontario, Canada), RDDS ||501||81% interested in GT if test is 80% predictive; 77% interested if test is 90% accurate; 67% interested if 1% of population inherits a familial CRC gene mutation|
|General population (Vermont, New Hampshire, Maine), RDDS ||1,836||GT intention in next 6 months: 32% probably/definitely; 19% possibly |
|GT intention in next month: 19% probably/definitely; 12% possibly|