Metastatic breast cancer: A regional audit of HER2 testing and trastuzumab access

Abstract

6097 Background: Clinical trials have clearly established that patients receiving taxane-based chemotherapy for metastatic breast cancer (MBC) should be treated with trastuzumab if their tumour is shown to overexpress the human epidermal growth factor receptor 2 (HER2) receptor. This is based on median survival gains for patients with HER2 positive tumours treated with trastuzumab plus taxane chemotherapy compared to taxane alone. Methods: Patients commencing chemotherapy for MBC in Northern Ireland in 2004 were identified from pharmacy records. Their case notes were retrospectively reviewed to determine whether patients in routine clinical practice had HER2 testing and trastuzumab treatment if indicated. Results: One hundred and fifty six patients commenced chemotherapy, of whom 145(93%) had HER2 testing. In 69(44%) patients the HER2 result was already available at the time of this relapse. In the remaining 76(49%) patients the result became available in a median of 41.5 (range 0–368) days. Of those tested, 48 patients (33%) were HER2 positive (immuno-histochemistry 3+ or fluorescence in situ hybridization positive). Thirty eight of these patients were treated with trastuzumab, either as a single agent or in combination with chemotherapy. There were valid reasons for trastuzumab omission in 7 of 10 patients not given trastuzumab (4 given first line anthracycline-based regimen, 1 had cardiac dysfunction, 1 had extensive lung metastastes and 1 was unfit for treatment). The data were examined for variations in chemotherapy and trastuzumab use across the 4 health boards which comprise the region. The number of patients commencing chemotherapy ranged from 6.9 to 11.4 patients per 100,000 population indicating a significantly different utilisation (p<0.001). Conclusions: In our region 145 of 156 patients who received chemotherapy for MBC were tested for overexpression of the HER2 receptor (93%). Of those patients who were eligible to receive trastuzumab 31 out of 34 (91%) received trastuzumab. There were inequalities in the region regarding chemotherapy for MBC and the time required to obtain a HER2 result averaged 41.5 days. Testing of HER2 status at time of original diagnosis would streamline management of metastatic disease. No significant financial relationships to disclose.