Despite substantial survival gains in early Her2 positive breast cancer (BC) associated with adjuvant trastuzumab, nearly 25% of patients will still relapse1. As the majority of evidence supporting trastuzumab use in the first line metastatic setting is in patients who didn’t receive prior trastuzumab, the impact of adjuvant anti-Her2 therapy in advanced disease has not been fully explored.
Prospective data was collected from four Australian sites participating in the TABITHA2 registry. We evaluated baseline patient and tumour characteristics of patients with HER2 +ve relapsed metastatic disease, as well as their treatment patterns and preliminary outcome data. Early relapse was defined as recurrence within 2 years of primary diagnosis.
64 of 109(59%) patients in the registry had relapsed rather than de novo metastatic Her2 positive BC. Median age was 58(range 35 – 84) and 56(88%) were ECOG 0-1. 41/64(64%) of relapsed patients received adjuvant trastuzumab. Analysis of time to recurrence among the 64 patients showed that patients with early relapse (n=20) were more likely to have positive nodes at diagnosis (15/20 vs 20/44;75 vs 45%,p=0.033), ER-ve disease (11/20 vs 13/44;55 vs 30%;OR=2.92,p=0.09) and brain metastases at first recurrence (7/20 vs 5/44;35 vs 11%,p=0.038). Early recurrence was not associated with size or grade of the primary tumour, adjuvant trastuzumab therapy, or presence of visceral metastases at recurrence. 11 of 20(55%) with early relapse received trastuzumab (either alone or in combination with pertuzumab) in the first line metastatic setting, compared to 38 of 44(86%) with later relapse (p=0.01). Early relapse was associated with poor survival (median 3.8 years vs 9.3+ years for later relapse;HR=0.44,p=0.11).
In this preliminary analysis of a prospective registry we identified a number of factors associated with early metastatic relapse in Her2 positive BC. Early relapse was associated with inferior overall survival.