Impact of study participation on survival of early-stage breast cancer patients: Results from the BRENDA study, a multicenter clinical cohort on quality of breast cancer care

521 Background: Over the past two decades significant progress in treatment of early breast cancer has been accomplished through well designed, clinical trials (CTs). It has been hypothesized that trial participation could also be beneficial for the individual breast cancer patient. The BRENDA study group has been analysing quality of care provided by one university based and 16 regional breast cancer centers in south germany. In this study we investigated the impact of study participation on survival in an unselected clinical cohort of early stage breast cancer patients. Methods: The study population includes 5,966 patients who received primary therapy for early breast cancer between 1992 and 2005. Influence on survival by study participation was calculated by Cox proportional hazard analyses. Model adjustments include prognostic factors, type of treatment, age, risk group and time period. Guideline compliant treatment was assessed based on the St Gallen expert consensus recommendations and the German na...