Background: The National Cancer Institute's Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial was designed to examine whether annual screening tests for these four tumor sites result in reduced disease-related mortality. We assessed the impact of trial participation on both health-related quality of life (HRQL) and trial adherence.
Methods: Participants (N = 432; 217 in the control arm and 215 in screening arm) were accrued from the Georgetown University PLCO site from May through December 1998. Screening-arm participants were interviewed by telephone at baseline (prescreening), shortly after notification of screening results (short-term follow-up), and 9 months after notification of screening results (intermediate-term follow up). Control-arm participants completed a baseline and 1-year follow-up assessment. Logistic regression analyses were conducted.
Results: Participants reported high levels of HRQL and satisfaction with their decision to participate. Screening-arm participants with abnormal screening results had a higher level of intrusive thoughts about cancer than those with all normal results (odds ratio [OR] = 2.9, 95% confidence interval [CI] = 1.3 to 6.3) at the short-term follow-up but not at the intermediate-term follow-up (when abnormal test results were known to be false positive; OR = 1.9, 95% CI = 0.89 to 4.2). Trial adherence was statistically significantly better among participants who had received all normal results in the previous year's screening tests (93.7% versus 78.7%; OR = 3.7, CI = 1.1 to 12.0) than in those who received at least one abnormal result. In the control arm, adherence (defined as returning annual questionnaires) was positively associated with education (OR = 3.4, 95% CI = 1.4 to 8.4) and sex, with women being more likely to return questionnaires than men (OR = 2.1, 95% CI = 1.05 to 4.4).
Conclusions: It is feasible to collect HRQL measures as part of a large cancer screening trial. Prior abnormal screening results were related to short-term HRQL but not to intermediate-term HRQL. Trial adherence was poorer among those who had received previous false-positive results. These results suggest several methods for improving adherence in this and other subgroups.