Participation in adjuvant clinical breast cancer trials: Is there a difference in survival compared to guideline adherent adjuvant treatment? A retrospective multicenter cohort study of 5,326 patients.

Abstract

1082 Background: Clinical trials (CT) usually compare a standard treatment regime versus innovative new substances or regimens. However participation in CT is available for only few patients and exclusion criteria is usually very strict. Therefore this study tries to answer the following questions: (1) Does participation in adjuvant CT improve survival in breast cancer (BC)? (2) Is there a difference in survival compared to guideline adherence and what is the role of the other treatments surrounding adjuvant breast cancer treatment? Methods: This German multi-center [17 participating hospitals all are certified as breast cancer centers] retrospective cohort study called BRENDA (BRENDA = quality of breast cancer care under evidence-based guidelines) included 5326 patients obtained from 1992 until 2005. The definition of guideline adherence was based on the German national S3 guideline for diagnosis and treatment of breast cancer (2004). Results: 554 (10,4%) patients participated adjuvant clinical trials and 4772 (89,6%) not. There was a trend towards a significantly impaired RFS [p=0.17; HR=0.87 (95% CI: 0.71-1.06)] and OAS [p=0.65; HR=0.84 (95% CI: 0.65-1.09)] when comparing participants (PA) versus non-participants (NPA). When stratifying for guideline adherence (compared to PA-guideline conform in all adjuvant therapies) the outcome was not different in NPA-guideline adherent [RFS: p=0.13; HR=1.25 (95% CI: 0.94-1.67)] [OAS: p=0.83; HR=1.41 (95% CI: 0.96-2.06)]. However survival parameters were significantly impaired in non-guideline conform PA [RFS: p=0.005; HR=1.66 (95% CI: 1.16-2.38)] [OAS: p=0.01; HR=1.83 (95% CI: 1.15-2.92)] and non-guideline conform NPA [RFS: p>0,001; HR=1.70 (95% CI: 1.27-2.26)] [OAS: p=0.002; HR=1.82 (95% CI: 1.24-2.67)]. Conclusions: There is a strong association between guideline adherence in adjuvant treatment in BC and survival. PA in clinical trials trended to an improved survival, but only if guideline adherent treatment was applied. Patients who don`t have access to clinical seem to profit substantially of guideline adherent adjuvant treatment.