Prescription patterns for metastatic breast cancer patients previously treated with anthracycline and taxane: An assessment in a United States managed care database

17056 Background: There is a scarcity of literature documenting actual prescription patterns for metastatic breast cancer (MBC) patients. The objective of this study was to describe the pattern of dispensing chemotherapy agents among MBC patients previously exposed to anthracycline and taxane in the managed care setting. Methods: Study cohort was extracted from the PharMetrics database between 1/1999 through 6/2005, who were =18 years, enrolled =6 months with =2 ICD-9-CM codes for breast cancer (BC), =1 ICD-9-CM code for distant metastases, and =1 NDC/J-code for anthracycline and taxane. A 21 day treatment interval was assigned to all agents to identify treatment regimens. If types of agents in consecutive intervals were the same, they were collapsed into one regimen disregarding the sequence. Following the reference date, the dispense date of the first anthracycline or taxane prescription, whichever occurred later, the first regimen was treated as reference regimen. Following this regimen, sequential monotherapy or combination therapy was identified in a chronological order. Results: Of the 1,028 who met inclusion criteria, 67% (n=691) did not receive a sequential therapy. Of the 33% (n=337) who did, the first sequential regimen for 177 was monotherapy and 160 combination therapy. The most common agents within the monotherapy regimens were taxanes 28%, capecitabine 20%, and trastuzumab 18%. For combination, taxane/trastuzumab 9.4%, vinorelbine/trastuzumab 9.4%, and carboplatin/taxane 8.8%. Of those who received sequential therapy, 68% were retreated with a taxane; 34% with docetaxel and 46% with paclitaxel. Conclusions: In this study, the majority of the population did not receive sequential therapy. This may have been due to loss to follow up, the duration of the reference regimen (lasting throughout the study period(s) after collapsing), or treatment in the inpatient setting where chemotherapy agents are not identifiable in this claims database. Taxane was the most common agent received in the first sequential therapy, both for monotherapy and combination therapy. A high proportion of patients with sequential therapy were retreated with a taxane. No significant financial relationships to disclose.