Practical aspects of clinical trials on chemoprevention of prostate cancer

In addition to the normal aspects of organizing clinical trials, the launch of a chemoprevention trial on prostate cancer needs extra effort. The sample size and duration of follow-up is so extensive that such a trial should be organized as an intergroup study, preferably worldwide. For that a central data center and data management is mandatory. Because healthy individuals are involved, refusal, loss to follow-up and inadequate adherence may be substantial. The choice of the study endpoint presence of prostate cancer or death due to prostate cancer will lead to completely different sample sizes and length of follow-up. Of criteria leading to the diagnosis of prostate cancer (PSA, DRE and transrectal ultrasound), at least two are rather subjective. The drug involved might affect the criteria for diagnosis. Because of the high incidence of clinically nonsignificant prostate cancer of men over 55, a large number of nonrelevant prostate cancers will be detected in both arms. Due to the long follow-up and alterations in the state of the art of detection and therapy of prostate cancer, the completion of such a study might be hampered. If the average price per patient involved in a clinical trial is currently between USD 1, 000 and 2,000, one may calculate that for 30,000 men, USD 20-40 million are needed, not including the hospital visits, examinations and biopsies. Economic considerations thus play a major role in organizing trials on the chemoprevention of prostate cancer.