Cost-effectiveness analysis of trastuzumab in the adjuvant setting for treatment of HER2-positive breast cancer

BACKGROUND. Adding trastuzumab to adjuvant chemotherapy provides significant clinical benefit in patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer. A cost-effectiveness analysis was performed to assess clinical and economic implications of adding trastuzumab to adjuvant chemotherapy, based upon joint analysis of NSABP B-31 and NCCTG N9831 trials. METHODS. A Markov model with 4 health states was used to estimate the cost utility for a 50-year-old woman on the basis of trial results through 4 years and estimates of long-term recurrence and death based on a meta-analysis of trials. From 6 years onward, rates of recurrence and death were assumed to be the same in both trastuzumab and chemotherapy-only arms. Incremental costs were estimated for diagnostic and treatment-related costs. Analyses were from payer and societal perspectives, and these analyses were projected to lifetime and 20-year horizons. RESULTS. Over a lifetime, the projected cost of trastuzumab per quality-adjusted life year (QALY; discount rate 3%) gained was $26,417 (range, $9104-$69,340 under multiway sensitivity analysis). Discounted incremental lifetime cost was $44,923, and projected life expectancy was 3 years longer for patients who received trastuzumab (19.4 years vs 16.4 years). During a 20-year horizon, the projected cost of adding trastuzumab to chemotherapy was $34,201 per QALY gained. Key cost-effectiveness drivers were discount rate, trastuzumab price, and probability of metastasis. The cost-effectiveness result was robust to sensitivity analysis. CONCLUSIONS. Trastuzumab for adjuvant treatment of early stage breast cancer was projected to be cost effective over a lifetime horizon, achieving a cost-effectiveness ratio below that of many widely accepted oncology treatments.