Cost-effectiveness of androgen suppression therapies in advanced prostate cancer

Abstract

Background: The costs and side effects of several antiandrogen therapies for advanced prostate cancer differ substantially. We estimated the cost-effectiveness of antiandrogen therapies for advanced prostate cancer. Methods: We performed a cost-effectiveness analysis using a Markov model based on a formal meta-analysis and literature review. The base case was assumed to be a 65-year-old man with a clinically evident, local recurrence of prostate cancer. The model used a societal perspective and a time horizon of 20 years. Six androgen suppression strategies were evaluated: diethylstilbestrol (DES), orchiectomy, a nonsteroidal antiandrogen (NSAA), a luteinizing hormone-releasing hormone (LHRH) agonist, and combinations of an NSAA with an LHRH agonist or orchiectomy. Outcome measures were survival, quality-adjusted life years (QALYs), lifetime costs, and incremental cost-effectiveness ratios. Results: DES, the least expensive therapy, had a discounted lifetime cost of $3600 and the lowest quality-adjusted survival, 4.6 QALYs. At a cost of $7000, orchiectomy was associated with 5.1 QALYs, resulting in an incremental cost-effectiveness ratio of $7500/QALY relative to DES. All other strategies—LHRH agonists, NSAA, and both combined androgen blockade strategies—had higher costs and lower quality-adjusted survival than orchiectomy. These results were sensitive to the quality of life associated with orchiectomy and the efficacy of combined androgen blockade, and they changed little when prostate-specific antigen results were used to guide therapy. Under a wide range of other assumptions, the cost-effectiveness of orchiectomy relative to DES was consistently less than $20 000/QALY. Androgen suppression therapies were most cost-effective if initiated after patients became symptomatic from prostate metastases. Conclusions: For men who accept it, orchiectomy is likely to be the most cost-effective androgen suppression strategy. Combined androgen blockade is the least economically attractive option, yielding small health benefits at high relative costs.

Cancer of the prostate is expected to cause more than 31 000 deaths in the United States in 2000. In previous years, annual Medicare expenditures for prostate cancer have exceeded $1.4 billion. Although metastatic prostate cancer is incurable, medical and surgical androgen suppression can palliate its symptoms and may prolong survival. Currently, there is little basis for determining which of the available androgen suppression treatments represents the best value. The efficacy of surgical androgen suppression (orchiectomy) is similar to that of any single medication, but the side effects and costs of each therapy differ substantially. Combination strategies may improve efficacy while increasing both toxicity and costs. Combinations of different classes of medications (a nonsteroidal antiandrogen [NSAA] with a luteinizing hormone-releasing hormone [LHRH] agonist) and of surgery plus medication (an NSAA) have been studied.

We evaluated the cost-effectiveness of androgen suppression in the form of orchiectomy, medication monotherapy, and combined androgen blockade. We also explored how cost-effectiveness varies with the time of initiation of therapy, whether prompted by symptoms or biochemical evidence of disease progression using prostate-specific antigen monitoring.