Prevalence and management of HER2/neu-positive early breast cancer in a single institution following availability of adjuvant trastuzumab

Aim: To ascertain the prevalence of HER2/neu‐positive early breast cancer (EBC), utilisation of adjuvant trastuzumab and incidence of cardiac toxicity in a community private hospital setting. Methods: Prospective data collected by breast oncologist and surgeons in all women diagnosed with EBC at the Mount Hospital (MH) were reviewed. Women with HER2/neu‐positive disease diagnosed between 1 October 2006 and 31 March 2009 were included in this analysis. Results: In total, 1128 women with invasive EBC were seen in the 30‐month period. All tumours underwent HER2/neu testing by immunohistochemistry, with 61% being evaluated by in situ hybridisation. Time to definitive HER2/neu result improved over time from median of 17 to 14 days. The prevalence of HER2 positivity (by in situ hybridisation) in this cohort was 12%. Uptake of trastuzumab‐based treatment was 100% in those patients receiving their treatment at the MH, compared to 52% of the 25 patients treated elsewhere. Ninety‐eight per cent of MH patients completed the planned 12 months of therapy, with one patient developing recurrent disease and two patients experiencing significant cardiac toxicity. Chemotherapy relative dose intensity was 98% in HER2/neu‐positive and negative patients. At a median of 25 months follow up, actuarial disease‐free and overall survival in the HER2/neu‐positive cohort is 99% and 100% respectively. Conclusion: In a community private hospital setting, adjuvant trastuzumab and chemotherapy was delivered optimally, in line with national and international guidelines. Early efficacy and safety results in a non‐clinical trial setting underscore the significant benefits achieved with this targeted therapy in HER2/neu‐positive EBC.