How interested is the public in genetic testing for colon cancer susceptibility? Report of a cross-sectional population survey.

Objective: To assess the public's interest in genetic testing for colon cancer susceptibility, to determine whether provision of information about the accuracy of the test or the population risk of inheriting the colon cancer gene influences interest, to determine the reasons for wanting to be tested and to identify the factors related to interest in testing.

Design: A cross-sectional random digit dialing telephone survey of 501 adults.

Setting: Ontario.

Main outcome measures: Proportion of the public interested in genetic testing; reasons for interest in testing.

Results: Of the sample, 39.9% (95% confidence interval [CI] 35.5 to 44.3) stated that they would be very interested in taking a simple blood test if a positive result suggested they had an 80% chance of getting colon cancer sometime during their lifetime. When it was suggested that the test might be accurate only 90% of the time, 33.1% of the sample (95% CI 28.7 to 37.5) still said they would be very interested in testing. When informed that less than 1% of the population inherits the gene for colon cancer, the proportion of the sample stating they would still be very interested in genetic testing fell to 19.2% (95% CI 14.8 to 23.6). The main reasons given for wanting genetic testing were to take preventive action, for peace of mind and curiosity. For respondents who remained interested in testing after being given information about the population risk of inheriting the gene, 2 factors were identified by logistic regression analysis as being independently related to interest: worry about cancer and perceived risk of getting colon cancer.

Conclusions: If the public's interest in testing for colon cancer susceptibility has any influence on its eventual request to be tested, then demand for genetic testing may be considerable once such tests become widely available and known to the public. This study reveals that the public's interest in genetic testing is substantial, although modifiable by the provision of information about the population risk of inheriting a colon cancer gene. This finding suggests that genetic researchers and others should be careful to provide the population risk of inheriting cancer genes when discussing the discovery of these genes with the media. Furthermore, public health educators will need to ensure that information aids include material on familial risk criteria, genetic counselling and genetic testing, as well as on the implications of genetic testing, the general population risk of developing colon cancer and the general population risk of carrying the colon cancer gene. This information should also be provided to those who seek assessment, to health care professionals and to the public.