The effect of clinical trial participation versus non-participation on overall survival in men receiving first-line docetaxel-containing chemotherapy for metastatic castration-resistant prostate cancer.
ABSTRACT Study Type - Prognosis (case series) Level of Evidence 4 What's known on the subject? and What does the study add? Previous studies have reported better outcomes in cancer patients that enrolled in clinical trials, suggesting that trial participation in itself might be beneficial. We investigated the potential positive effect of clinical trial participation on survival outcomes of patients with metastatic castration-resistant prostate cancer who were treated with first-line docetaxel-containing chemotherapy. After accounting for potential baseline inequalities, participation in a clinical trial itself was associated with significantly longer overall survival in these patients. OBJECTIVE: • To study differences in baseline characteristics and outcomes of patients with metastatic castration-resistant prostate cancer (mCRPC) receiving first-line docetaxel-containing chemotherapy on prospective clinical studies (trial participants) versus those receiving this therapy outside of a clinical study (non-participants). PATIENTS AND METHODS: • Records from 247 consecutive chemotherapy-naive patients who were treated with docetaxel-containing chemotherapy for mCRPC at a single high-volume centre from 1998 to 2010 were reviewed. • All patients received docetaxel either as clinical trial participants (n= 142; 11 separate studies) or as non-participants (n= 105). • Univariable and multivariable Cox regression models predicted overall survival after chemotherapy initiation. RESULTS: • There was no significant difference between trial participation and non-participation with respect to patient age, type of primary treatment, tumour grade or clinical stage. • Multivariable analyses showed a significantly lower risk of all-cause mortality (hazard ratio 0.567; P= 0.027) among trial participants vs non-participants. CONCLUSIONS: • Patients that were treated with docetaxel for mCRPC showed a significantly longer overall survival when enrolled in a clinical trial. • Improved survival in trial participants may reflect the better medical oversight typically seen in patients enrolled in trials, more regimented follow-up schedules, or a positive effect on caregivers' attitudes because of greater contact with medical services. • With the retrospective nature of this analysis and the small study population, prospective studies are needed to validate the present findings and to further investigate the relationship between clinical trial participation and outcomes.