We mailed invitations to 1,294 relatives and 866 controls. A total of 397 (18.4%) study participants were not reached despite the initial mailing and 5 follow-up phone calls. Of those who were successfully contacted, 947 (43.8%) declined participation via the self-addressed postcard or at the follow-up phone call. An additional 336 (15.6%) respondents were deemed ineligible after contact by the study coordinator for one of two reasons: (1) the individual was unable or unwilling to access the internet; (2) the respondent had a severe illness that prevented completion of the survey. After answering the family history questions, 20 people in the control group revealed a family history of colorectal cancer which was unknown at the time of their initial C-CFR interview and were thus re-categorized as relatives. After reassigning those 20 participants to the relative category, as they now had a family history of colorectal cancer, a total of 310/1,314 (23.6%) relatives and 170/846 (20.1%) controls completed the survey.
We conducted a logistic regression of all relatives and controls to examine factors associated with nonresponse. We first excluded those who were found to be ineligible after approach. Among eligible participants, male sex and African American race (vs. white) were significantly associated with survey nonresponse. College and graduate school education was associated with higher likelihoods of survey response.
Tables and list demographic characteristics, health behaviors, and HRQOL responses of the respondents, stratified by whether they were a relative or a control. Compared to controls, female relatives were significantly younger, less highly educated, and reported a significantly higher average number of relatives with colorectal cancer and any cancer. The proportion of women was not statistically different in the two groups.
Demographics and characteristics of respondents
Self-reported screening and lifestyle behaviors of respondents
A higher proportion of controls compared to relatives reported either accompanying a family member through treatment for any cancer or speaking frequently with him or her during treatment (table ). Table also shows individuals’ ratings of their current HRQOL, as measured by EQ-5D, VAS, and standard gamble scores. There was no significant difference between relatives and controls on any of these summary measures of health status. There also was no significant difference in diet, alcohol, or tobacco use between groups. Relatives were significantly more likely to have had colorectal cancer screening, but were less likely to exercise regularly. Relatives generally reported a higher estimated lifetime risk of developing colorectal cancer than controls, most notably among persons between the ages of 46 and 55 (estimated lifetime risk: 29% and 9%, respectively, p < 0.0001).
Adjusting for participant age, individuals’ assessments of their lifetime cancer risk was significantly higher for relatives versus controls and significantly associated with receipt of colorectal cancer screening within the recommended time frame (p < 0.0001 in both instances).
Tables and summarize responses to the hypothetical questions regarding worry/relief, informing friends and family, and intent to modify lifestyle and screening behavior after learning about gene variant carrier status.
Participant responses to questions concerning anxiety/relief, exercise, diet, and screening behavior under a hypothetical scenario where they are told they are a colorectal cancer polymorphism carrier
Participant responses to questions concerning anxiety/relief, exercise, diet, and screening behavior under a hypothetical scenario where they are told they are a noncarrier of colorectal cancer polymorphism
Positive Test (Carrier) Scenario
Cancer Worry. Under the scenario of having a cancer-associated gene variant, 69% of all respondents recorded that they would be ‘somewhat’ worried by the results; 18% would be ‘very’ worried. The proportion who stated they would remain ‘very worried’ at 1 year following the test was not significantly different from the immediate scenario. There was no significant difference in the percentage of relatives who reported being ‘very worried’ at a positive gene variant result compared to controls. Among relatives, there was no relationship between the number of relatives with colorectal cancer and their degree of worry in response to the scenario of having a positive gene variant result (p = 0.84). Among relatives and controls, the level of a participant's involvement with a family member with cancer and their degree of worry in response to the scenario of having a cancer-associated gene variant did show a statistically significant association (p = 0.008) with higher worry for those with greater involvement.
Willingness to Tell Others about Test Results. Overall, nearly 88% of respondents reported that they would tell their spouse if they had a positive test; approximately three-fourths would tell their siblings. More than 50% would tell children, parents, or close friends about the results. Less than 3% said they would tell ‘no one’ about the result. There was no significant difference between relatives and controls in terms of willingness to tell others about the test result.
Intent to Change Diet, Exercise, and Colorectal Cancer Screening. About 25% of all participants stated they would exercise ‘a lot’ more and 30% would make ‘big changes’ in their diet. There was no significant difference between relatives and controls in stated intent to change these behaviors. Fifty percent of all participants stated that they already were receiving regular colorectal cancer screening, but significantly more relatives than controls had already had screening (p < 0.001). Among those who did not currently report screening, 43% stated that they would start. Controls were significantly more likely to state intent to start screening than were relatives (p = 0.03).
Negative Test (Noncarrier) Scenario
Cancer Worry. Under the scenario of a negative gene variant test, 46% of all respondents said they would be ‘a little relieved’; 33% said they would be ‘very relieved.’ There was no significant difference between relatives and controls.
Willingness to Tell Others about the Test Result. As with the positive result, most stated that they would tell their spouse and siblings about a negative test result. Fewer than 50% would tell their children, parents or close friends. There was no significant difference between relatives and controls in terms of willingness to inform others.
Intent to Change Diet, Exercise, and Colorectal Cancer Screening. Fewer participants indicated that they would make substantial differences in their diet and exercise if the gene variant test came back negative: 60% would not change their diet and 64% would not change their exercise. Only 5% indicated they would exercise ‘a lot’ more and only 2% would make ‘big changes’ in their diet. A smaller proportion of those who were not current regular screeners indicated they would seek screening (26%) compared to the positive test scenario. There was no difference in responses to the diet, exercise and screening questions for relatives and controls.
Standard Gamble Interview Results: Current Health versus Carrier State
Relatives’ and controls’ general health state utilities, as measured by the standard gamble, were similar. Both relatives and controls had modestly lower utility scores for the gene variant state compared to current; the difference was significant only for relatives (controls 0.89 vs. 0.88, p = 0.11; relatives 0.90 vs. 0.88, p = 0.02). When standard gamble scores were adjusted for respondent characteristics on multivariate analysis, the gene variant state was not significantly associated with lower utility scores.
Respondent Factors Associated with Changes in Health Habits and Screening following Gene Variant Testing
Generalized linear models were used to determine whether patient factors modified the effects of the hypothetical gene variant carrier status on overall health state, cancer worry, health habits, and intentions towards screening compared to reported levels prior to the gene variant testing scenario. In the gene variant positive scenario, no single factor was significantly associated with changes in worry, with intentions to change exercise or diet, or with intentions to adhere to screening recommendations. Being told one did not have a cancer-associated gene variant was also not significantly associated with relief or worry, was not significantly associated with intentions to change exercise, diet, or adherence to screening recommendations. For each of these models, being a relative of a cancer patient did not influence the significance of the associations.