Background: Approximately 14% of Early Breast Cancers, EBCs, and 25% of Metastatic BCs, MBCs, are HER2 positive. There is an effective treatment (trastuzumab) for both EBC (9% increased absolute disease free survival at five years) and MBC (five to nine months' prolonged overall survival). Patients with BC are treated within each of the six different Health Care Regions (HCRs) in Sweden. This aim of this project was to study the introduction and usage of trastuzumab in BC in the six HCRs in Sweden.
Materials and methods: We used official sales data and cancer statistics in the model, and HER2 positive proportions of 25% (prevalent population in year 2000; first year of trastuzumab sales) and 14% and treatment times of 38 weeks and 52 weeks for MBC and EBC, respectively, based on clinical trial data. We used years 2000-2004 for the MBC analyses. In year 2005 data on trastuzumab in EBC were presented, and approval came in year 2006. We studied years 2006-2008 for the use in both EBC and MBC.
Results: The percentage trastuzumab treated MBC patients for the entire period in the different HCRs (quarter 4 2000 to end 2004) was: North 57%, Stockholm 48%, South East 40%, South 17%, Uppsala 52%, West 34%. The Sweden average was 40%. The percentage treated patients (MBC and EBC), years 2006-2008 in the different HCRs was: North 68%, Stockholm 75%, South East 43%, South 44%, Uppsala 74%, West 43%. The Sweden average was 59%.
Conclusion: The differences in usage of trastuzumab may be explained by variable interpretations of the clinical data and applications in clinical practice, budget issues and differences in coordination, experience and training.