Does enrollment setting influence patient attributes and outcomes in RTOG prostate cancer trials?

4607 Background: The external validity of randomized trials (generalizability) has been called into question following the finding that patients treated on clinical trials vary substantially from patients treated in the usual care setting. The purpose of this secondary analysis is to examine whether results of prostate randomized trials within the RTOG differ according to enrollment setting. METHODS: 4,154 patients accrued into one of 4 RTOG trials between 1987-1999 were included in this analysis. There were 224 North American institutions enrolling in one or more trials. Patient attributes were compared by enrollment settings, controlling for trial. Survival regression models stratified by trial and including patient attributes were used to evaluate survival differences by enrollment setting. RESULTS: Academic institutions enrolled 36% of patients; community centers enrolled 49%; CCOPs enrolled 14%, and VHAs enrolled 2%. With respect to patient attributes, men from Academic and VHA centers tended to have better performance status, black men were less frequently enrolled from non-CCOP community institutions, and Gleason scores tended to be higher in men from CCOPs. Age at diagnosis did not differ materially by enrollment setting. Adjusted for patient attributes, survival by enrollment setting did not differ significantly (Table). CONCLUSIONS: Attributes of prostate cancer patients enrolled in these RTOG trials Phase III differed modestly according to enrollment site type. Accounting for these differences, overall survival did not depend on the type of institution from which patients were enrolled. These findings support the external validity of RTOG prostate trials.This project was supported by RTOG grant U10 CA21661, and CCOP grant U10 CA37422 from the National Cancer Institute (NCI). [Table: see text].

Duke Scholars

Author W. Robert Lee Radiation Oncology