Prostate cancer, comorbidity, and participation in randomized controlled trials of therapy

Randomized controlled trials (RCTs) evaluate the potential benefits of chemotherapy regimens and guide clinical care for patients with cancer. Inclusion criteria for RCTs are usually stringent and may exclude many patients seen in clinical practice. Our objective was to determine the proportion of men with castrate-resistant prostate cancer (CRPC) in a clinical setting that would have been excluded from major phase 3 RCTs.

We reviewed eligibility criteria from 24 phase 3 clinical trials evaluating chemotherapy for CRPC active from January, 2004, through April, 2008. We created a common list of criteria used in at least 3 studies and separately considered the criteria from a prominent RCT (TAX 327). We applied these criteria to a population of patients with CRPC treated during 2004 to 2006 at the Veterans Affairs Connecticut Healthcare System.

Among 106 patients with CRPC, 99 (93%) had complete medical records, and 45 (45%) of the 99 would have been excluded from RCTs. Common reasons for exclusion were abnormal laboratory values, other malignancies, and other serious medical conditions including cardiac disease.

Almost half of the CRPC patients examined in a clinical setting would have been ineligible for phase 3 RCTs, highlighting that such trials may not be applicable to general oncology practice.