Long-term outcome data for patients with HER2-positive early-stage breast cancer treated with adjuvant trastuzumab: benefit outside clinical trial setting

Adjuvant treatment options for HER2 positive Early-Stage Breast Cancer (EBC) have grown in recent years. The addition of adjuvant trastuzumab therapy for one-year to standard chemotherapy has been shown in several Randomized Controlled Trials (RCTs) to improve Disease-Free Survival (DFS) and Overall Survival (OS) in patients with high-risk HER2-positive EBC. This study aimed to review the long-term outcome data for patients with HER2-positive EBC who were treated with adjuvant trastuzumab therapy in a designated cancer centre. Methods: Data included all women diagnosed with HER2-positive EBC between 1st January 2001 and 31st January 2010 (N=147). Retrospective evaluation of healthcare records for clinical, demographic, and pathologic data was undertaken. Most had adjuvant trastuzumab following systemic chemotherapy (80/147; 54.4%). Kaplan-Meier estimates were used to evaluate whether one-year trastuzumab administration was associated with improved DFS and OS. Additionally, cohorts were generated by pathologic tumour size and lymph node involvement to stratify outcome measures (i.e. DFS and OS) by risk features