Impact of trastuzumab treatment beyond disease progression for advanced/metastatic breast cancer on survival - results from a prospective, observational study in Germany.

Abstract Objectives Evidence suggests that continued trastuzumab therapy beyond progression (TBP) may provide additional survival benefit. Within the framework of an observational prospective study of patients with advanced/metastatic breast cancer receiving trastuzumab in routine clinical practice, we had the opportunity to examine the effect of TBP in a large population. Patients and methods Among a total of 1843 trastuzumab-treated patients, a sub-cohort of 418 fulfilled the selection criteria for the TBP analysis: 261 continued trastuzumab and 157 discontinued. Logrank tests and Cox models were used to compare survival and identify prognostic factors. Results Survival from progression was significantly longer in those patients continuing trastuzumab treatment beyond disease progression (TBP: median 22.1 months; no TBP: median 14.9 months; HR  = 0.64; P  = 0.00021). In addition to TBP, a positive endocrine receptor status, a longer relapse-free interval, no visceral metastasis, no concomitant chemotherapy during first-line treatment, and first-line response were independently significant prognostic variables for longer survival on multivariate analysis. Conclusion The hitherto limited evidence for TBP benefit from randomized studies was confirmed. While a number of strong disease-related predictors for survival after first progression could be identified, the positive effect of trastuzumab continuation retained statistical significance in a multivariate model.