Quality of life endpoints in prostate chemoprevention trials

Although the ultimate goal of any chemoprevention study is to extend life by preventing cancer, it is also important that in doing so, the quality of life is not reduced. Hence, quality of life (QOL) endpoints are secondary only in importance to survival as an endpoint for prostate chemoprevention trials. One can conceptualize QOL endpoints as just another surrogate endpoint biomarker. QOL can be administered and collected in a valid and reliable fashion from cancer patients as demonstrated by numerous clinical trials. To date more than 25 prostate cancer QOL tools have been developed with over 700 different items. However, patients may be asymptomatic, leaving the sensitivity and specificity of the QOL instrumentation in question. Judicious use of a global QOL measure supplemented by protocol-specific or disease-specific instruments is an efficient approach for prostate chemoprevention trials. Clinical significance and missing data considerations need to be elucidated a priori in definitive terms so that results are directly interpretable from the data obtained. The effect of chemopreventive agents on QOL needs to be sufficiently modest to be practical to justify administration in a healthy population. As such, great care needs to be given to a priori determination of the QOL constructs that are most likely to change.