Cost-effectiveness analysis of adjuvant docetaxel, doxorubicin, and cyclophosphamide (TAC) for node-positive breast cancer: modeling the downstream effects

Purpose BCIRG 001 demonstrated prolonged disease-free (DFS) and overall survival (OS) but increased toxicity for adjuvant docetaxel, doxorubicin, and cyclophosphamide (TAC) versus 5-fluorouracil, doxorubicin, cyclophosphamide (FAC) in women with node positive breast cancer (BC). This study evaluates quality-adjusted survival and cost-effectiveness of adjuvant TAC versus FAC, taking downstream decisions and events into account, including palliative chemotherapy with taxanes. Methods We developed a Markov model for a cohort of women with node positive BC eligible for adjuvant anthracyclines. Data input included clinical and resource utilization data collected prospectively from BCIRG 001. Treatment decisions and outcomes with disease recurrence were based on a systematic literature review with validity reviewed by a national panel of Canadian BC oncologists. Direct costs for resource utilization following Canadian practice patterns were included. Unit costs were obtained from provincial cost list and published drug list prices. Utility scores were derived from the literature. An incremental cost-effectiveness ratio (ICER) in cost per quality-adjusted life-years (QALY) gained for TAC versus FAC was calculated. Results For 1,000 women with node positive BC, the model showed that TAC would lead to a gain of 313 QALY (370 life years) at an additional cost of $5.8 Million Canadian dollars (Cdn) compared to FAC, over a 10-year time horizon. The ICER of TAC versus FAC was $18,505.54 Cdn per QALY gained. Sensitivity analyses supported the robustness of the model. By one-way sensitivity analyses of over 50 model variables, 95% of the cumulative ICER variation was from $6,000 to $28,000 Cdn/QALY. By multivariate Monte Carlo simulation, there was a 70% probability that the ICER would be under $50,000 CdN/QALY. Conclusion For women with node positive BC, TAC improves DFS and OS compared to FAC and is a cost-effective adjuvant chemotherapy strategy.