Participants’ Views of Retention Materials Used in the PLCO Cancer Screening Trial

The ability of clinical trials to rigorously examine research questions depends on many factors. Careful adherence to clinical aspects of the protocol is of the utmost importance, yet a trial cannot be successful unless participants actually participate and continue to do so throughout the trial. They must adhere to trial regimens and must provide information, typically through interviews or questionnaires at pre-specified intervals, so that trial outcomes can be tracked. Lack of participation can result in meaningful decreases in statistical power; all clinical trials must account for that possibility when calculating necessary sample size, both at the beginning of the trial and throughout its course. Participants comply for many different reasons. Some comply because they are receiving an experimental treatment for an otherwise thought-to-be incurable illness; others comply because they receive medical care that they otherwise would be unable to afford. But many participants, especially those in prevention trials of relatively rare diseases, comply even though their chance of direct benefit is quite small, and the impact of their altruistic efforts cannot be immediately or easily measured. In such instances, reasons for compliance, both initial and continued, can be enigmatic. Researchers must carefully consider strategies that will keep participants engaged in the trial, willing to adhere to study interventions, and willing to provide information when queried. This is of particular importance in long-term prevention trials, where it can take many years to accrue the necessary number of events. The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial was a large, long-term, multi-phasic study of cancer screening. Throughout the trial, investigators and study coordinators spent much time and effort on development and implementation of retention strategies. While the experience of other large, long-term cancer primary and secondary prevention trials would have been of value, none had published on participant reactions to retention materials prior to the end of PLCO, and to the best of our knowledge, still have not. Near the end of the trial, three of the ten screening centers chose to query participants as to their opinions of the various retention materials, including whether they would have been willing to use electronic communication for study activities, had the option been available. In this manuscript, we report on the findings of that survey.