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

Abstract

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 national S3 Guidelines. Results: A total of 738 patients (12%) received adjuvant (n = 552) or neoadjuvant (n = 186) systemic therapy within one out of 42 registered prospective multicenter phase II or III clinical trials. For patients not receiving neoadjuvant systemic therapy trial participation was associated with improved overall and disease free survival (hazard ratio [HR] = 0.75, 95% confidence interval [CI] 0.57–0.99, HR = 0.78, CI 0.63 - 0.97, respectively). The calculated effect was of similar magnitude after additional adjustment for co-existing morbidity of patients. Descriptional analysis revealed that guideline violations for locoregional or systemic treatment were more frequently found in patients receiving adjuvant treatment outside CTs. No significant effect on survival was calculated for 183 patients receiving neoadjuvant systemic therapy within CT protocols. Conclusions: In our study population participation in prospective clinical trials for adjuvant systemic therapy was associated with improved survival irrespective of treatment actually given. Intrinsic mechanisms within the framework of clinical trials can improve quality of breast cancer patient care. No significant financial relationships to disclose.