Participation rates of Ashkenazi Jews in a colon cancer community-based screening/prevention study.

In a recent colon cancer risk study, genetic assessment and colonoscopy were offered to virtually all of the adult Ashkenazi Jews in an urban community. The present study was designed to examine factors influencing participation and response in the initial study and to suggest strategies for improving participation in future health promotion programs. The study comprised a random sample of three groups of individuals who had been targeted for participation in the previous study: those who had (a) agreed to participate (n = 234); (b) declined participation (n = 179); and (c) failed to respond to a mailed recruitment package (n = 128). All participants completed a brief telephone survey. Key multivariate predictors of both response and participation were individuals' perceptions of the drawbacks of participating in colon cancer screening research and the degree of decisional conflict they experienced. Response was further predicted by the influence of spouses, family history of colon cancer, past knowledge of genetic testing for colon cancer, and education level. Participation was predicted by awareness that the study was supported by the Ashkenazi Jewish community, past experience with genetic testing, individuals' perceptions of the benefits of participating, and whether or not they had children. The degree to which individuals understand the purpose and nature of genetic screening research, along with their levels of decisional conflict and other psychosocial factors, may influence the likelihood of their participation in such research. Results of this study suggest a number of possible strategies for improving participation and response rates in disease prevention and detection studies.

APC I1307K increases risk of transition from polyp to colorectal carcinoma in Ashkenazi Jews.

BACKGROUND & AIMS: The I1307K allele of the APC gene has been shown to confer a modestly elevated risk of colorectal cancer in the Ashkenazi Jewish population (relative risk, 1.5-1.7). However, it is unclear whether the alteration predisposes to adenomas and whether the genetic information can be used in clinical practice. To further address the pathogenic significance of I1307K, we offered both a genetic test and a screening program to individuals considered to be at increased risk for colorectal cancer. We compared the prevalence of polyps and their characteristics between carriers and noncarriers. METHODS: Invitations to participate in a DNA and colonoscopy screening program were mailed, together with a family questionnaire, to 3540 households forming the Jewish Community in Ottawa. The I1307K variant was analyzed in 242 eligible respondents who were selected because they had a personal or family history of colon cancer. Nearly 80% of these respondents (n = 189; age range, 32-83 years) consented to undergo a single colonoscopic examination. RESULTS: The overall carrier frequency of I1307K in the study group was 10.3%. A higher proportion of heterozygous gene carriers was found in the subgroup of colon cancer survivors (27%) than among asymptomatic individuals (8%, P < 0.02). A total of 59 polyps were identified in 44 subjects. Histologically confirmed adenomatous polyps were diagnosed in 11.8% of carriers and 12.8% of noncarriers (P > 0.5). No significant differences in polyp size, multiplicity, location, degree of villosity, or age-dependent prevalence were found between the 2 groups of participants. CONCLUSIONS: The high frequency of I1307K colorectal cancer patients found in the Ashkenazi Jewish community of Ottawa and the equivalent proportion of carriers and noncarriers who developed adenomatous polyps suggest that in this community, I1307K is associated with a significant predisposition to carcinoma but not adenoma.

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.