An economic evaluation of docetaxel and paclitaxel regimens in metastatic breast cancer in the UK.

Paclitaxel and docetaxel have been available for the treatment of metastatic breast cancer (MBC) since the 1990s. However, until very recently, comparisons between these two drugs have been difficult due to lack of direct comparative clinical evidence and differences in trial patient populations. To conduct a cost-effectiveness analysis comparing docetaxel with paclitaxel regimens in the treatment of MBC previously treated with an anthracycline from the perspective of the UK NHS. A cost-utility analysis was performed using a Markov model to compare taxanes in MBC patients who had progressed after treatment with an anthracycline-containing chemotherapy regimen: docetaxel 100 mg/m2 1-hour intravenous (IV) infusion every 21 days versus paclitaxel 175 mg/m2 3-hour IV infusion every 21 days (Pac3w). In parallel, additional analyses were performed versus paclitaxel administered in 1-weekly cycles (Pac1w), and a nano albumin-bound form of paclitaxel (Nab-P) given every 3 weeks. Progression-free survival (PFS), overall survival (OS) and adverse events used in the model were derived from a randomized trial directly comparing docetaxel with Pac3w; the comparisons of docetaxel versus the other two paclitaxel regimens were indirect, using patient-level data from a trial comparing Pac3w with Pac1w, and from the published literature comparing Pac3w with Nab-P. Utility values for response, progression and adverse events were derived from the literature. Direct treatment costs related to progression, best supportive care and adverse events were estimated using clinical trials data, published literature, NHS reference costs and published drug prices. The estimated costs of growth colony-stimulating factors and blood transfusion were also included in the model. The model was used to predict the expected total costs ( pound, year 2005-6 values), QALYs gained, incremental cost/life-year gained (LY) and cost/QALY over a 10-year time period. In the base-case analysis, docetaxel improved QALYs by 0.33, 0.29 and 0.22 compared with Pac3w, Pac1w and Nab-P, respectively. The incremental cost-effectiveness ratios (ICERs) for docetaxel were pound 12 032/QALY versus Pac3w, pound 4583/QALY versus Pac1w and pound 14 ,694/QALY versus Nab-P. The ICER was sensitive to the hazard ratios for PFS and OS between the comparators, the drug cost of initial treatment and the treatment costs after progression. Taking into account parameter uncertainty, and comparing all four treatments simultaneously, at a willingness to pay of pound 20,000 per QALY gained, the probability of docetaxel being the most cost-effective treatment was around 70%. In the base-case scenario, docetaxel compared with Pac3w is estimated to have a cost-effectiveness ratio that falls within the acceptable threshold in the UK. The study also suggests that docetaxel may be cost effective versus Pac1w and Nab-P, although there is more uncertainty around these findings.