Overall survival of men with metastatic castration-resistant prostate cancer (mCRPC) receiving first-line docetaxel-containing chemotherapy according to their participation (or not) in clinical trials

148 Background: There is insufficient evidence to determine whether clinical trial participation can itself lead to improved clinical outcomes in patients with mCRPC treated with docetaxel chemotherapy. We compared clinical characteristics and survival outcomes of patients with mCRPC receiving first-line docetaxel-containing therapy on a clinical study (trial participants) or outside of a clinical trial (non-participants). Methods: We retrospectively reviewed the records of 245 consecutive chemotherapy-naïve patients with mCRPC who received docetaxel-containing therapy between 1/1/1998 and 1/1/2010, either as trial participants (n=142; 11 separate studies) or as non-participants (n=103). Patient demographics, baseline clinical characteristics, treatment details and follow-up data were recorded. Results: In unadjusted analysis, trial participants were more likely to be white (83 vs 70%, p=0.005), to have better ECOG performance status (p=0.01), higher baseline hemoglobin (12.4 vs 11.6 g/dL, p=0.0003), higher albumin (4.3 vs 4.0 g/dL, p=0.009), lower creatinine (0.90 vs 1.04 mg/dL, p=0.01), and to have received a higher number of chemotherapy cycles (6.6 vs 5.1, p=0.001) than non-participants. In Kaplan-Meier analysis, median overall survival was significantly longer among trial participants vs non-participants (21.3 vs 17.1 months, p=0.024). In multivariable analysis, trial participation (HR 0.53, p=0.013), more chemotherapy cycles (HR 0.87; p=0.0002), baseline hemoglobin >12 g/dL (HR 0.67, p=0.016), lower ECOG score (HR 0.57, p=0.026) and lower baseline (log) PSA (HR 0.85, p=0.012) were all found to be independent predictors of survival. Conclusions: Clinical trial participation is an independent positive predictor of overall survival in men undergoing first-line docetaxel-containing chemotherapy for mCRPC. Improved survival in trial participants may reflect better medical oversight typically seen in patients enrolled in clinical trials, more regimented follow-up schedules, or a positive effect on caregivers’ attitudes due to greater contact with medical services.