- Long-term trastuzumab responders (LTR) with human epidermal growth factor receptor 2 (HER2)+ metastatic breast cancer have twice the survival as non-LTR.
- Factors predictive of LTR include number of metastatic sites, taxane-based chemotherapy, and maintenance endocrine therapy.
Why this matters
- One of the first real-life studies to compare LTRs with non-LTRs.
- A retrospective cohort (n=422) of the French Epidemiological Strategy and Medical Economics (ESME) Program-Institute Curie breast database.
- ESME was analyzed from 2008 to 2014; Institute Curie from 2004 to 2008. Both were maintained by a single institute.
- LTR was defined as nonprogressive disease for ≥2 years on first-line trastuzumab.
- Funding: None disclosed.
- Median follow-up was 48 months.
- 111 of 422 subjects were LTR (26.3%).
- LTR had a median OS of 110 (95% CI, 95-not reached) months vs 56 (95% CI, 47-68) months among non-LTR.
- Multivariate predictive factors for LTR included:
- Fewer number of metastatic sites (≤2 vs >2; P=.01).
- Receipt of taxane-based first-line chemotherapy (vs no receipt) for primary breast cancer (P=.003).
- Receipt of maintenance endocrine therapy+trastuzumab (vs no receipt; P=.001).
- Single-center study.
- Retrospective, observational design.