Cancer survivors' uptake and adherence in diet and exercise intervention trials: an integrative data analysis.

BACKGROUND The health benefits of diet and exercise interventions for cancer survivors are well documented. However, little is known regarding demographic and medical predictors of survivors' willingness to participate in diet and exercise intervention trials, study enrollment, intervention adherence, and study completion. To assist in interpreting the generalizability of trial findings and to improve the design of future trials, this study examined predictors of these process measures. METHODS An integrative data analysis was performed on data from 3 of the largest home-based diet and exercise intervention trials for cancer survivors (n = 23,841). Demographic and medical factors (ie, sex, race, age, time since diagnosis, and cancer type) were examined as predictors of willingness to participate, study enrollment, intervention adherence, and study completion in the pooled sample. A 99% confidence interval was used to determine statistical significance. RESULTS Across trials, 11.1% of contacted survivors were willing to participate, and 5.7% were eligible and enrolled. Among enrollees, 53.4% demonstrated ≥75% adherence to the intervention, and 91.1% completed the study. Race (Caucasian vs others), age, time since diagnosis, and cancer type predicted survivors' willingness to participate (P < .01). All examined predictors were associated with the likelihood of study enrollment (P < .01). No significant predictors of intervention adherence or study completion were found among study enrollees (P ≥ .01). CONCLUSIONS Cancer survivors' demographic and medical characteristics predicted their interest and participation in diet and exercise intervention trials. These findings have implications for the generalizability of results and can help to guide procedures used in future trials to enhance patient representation.