Exploring the use and impact of adjuvant Trastuzumab for HER2-positive breast cancer patients in a large UK cancer networkDo the results of international clinical trials translate into a similar benefit for patients in South East Wales

Background: Trastuzumab was approved in the United Kingdom for adjuvant treatment of human epidermal growth factor receptor 2 (HER2) breast cancer in 2006 at significant economic cost and with limited evidence in smaller T1N0 tumours. The South East Wales Cancer Network covers a population of 1 420 000 and maintains a database of treatments used. We examined this database to ensure the outcome of Trastuzumab use is as expected, especially in patients with T1N0 cancers.Ethods:M Case notes of patients with HER2 disease eligible for adjuvant Trastuzumab over 2005-2008 were reviewed. Disease-free survival (DFS) and overall survival (OS) were calculated with the Kaplan-Meier method using SPSS (version 16.0.01 for Windows, SPSS, Chicago, IL, USA). Results: A total of 239 of 338 (70.7%) eligible HER2 patients received treatment. At 3 years, the DFS of the treated group was 90.3% vs 73.3% and the OS was 98.5% vs 87.6%. In all, 47 of 92 stage I patients received Trastuzumab. Despite a trend towards worse prognostic factors in the treated group the DFS was 100% vs 84.1% and the OS was 100% vs 93.3%. Conclusion: Our results are comparable to those from landmark Trastuzumab trials. As evidence continues to emerge that smaller HER2 cancers may behave aggressively our analysis of stage I tumours adds further support to the use of Trastuzumab in these patients.