Treatment (tx) patterns and clinical outcomes for patients (pts) with de novo versus recurrent HER2+ metastatic breast cancer (MBC).

Abstract

523 Background: Use of adjuvant trastuzumab (T) in pts with HER2+ early breast cancer is associated with decreased recurrence. As fewer patients relapse, the proportion of pts with de novo metastatic disease in the first-line (1L) setting will increase, which could have implications for the design/interpretation of results from HER2+ MBC trials. To date, little data exist on potential differences in prognosis and outcomes between pts with recurrent vs de novo HER2+ MBC. Methods: registHER is an observational cohort of pts with HER2+ MBC diagnosed ≤6 mo from enrollment and followed until death, disenrollment, or June 2009 (median follow-up: 27 mo). Demographics and 1L tx patterns (using descriptive analyses), as well as clinical outcomes (median PFS and OS estimated by Kaplan-Meier method) were examined for pts with de novo vs recurrent HER2+ MBC. De novo was defined as disease-free interval (DFI) between initial and metastatic diagnosis ≤90 days; recurrent was defined as DFI >90 days. Cox regression analyses were used to generate hazard ratios (HRs). Results: Pts with de novo HER2+ MBC (327 of 1001 enrolled) were more likely to be younger and non-white; have lymph, bone, and/or liver metastases and >4 sites of metastatic disease; less likely to have lung or CNS metastases; and have received 1L regimens of TCH or AC more frequently vs pts with recurrent disease (who received T + vinorelbine more frequently). PFS and OS were longer in the de novo vs recurrent group (Table). Conclusions: Despite presenting with more advanced-stage disease accompanied by higher tumor burdens, pts with de novo HER2+ MBC had more favorable clinical outcomes vs those with recurrent disease. Differences in disease characteristics and tx patterns resulting in more refractory disease (including acquired resistance from adjuvant tx) may account for these observations. Clinical trial information: NCT00105456. [Table: see text]