Decision-analytic model and cost-effectiveness evaluation of postmastectomy radiation therapy in high-risk...

To present a decision model that describes the clinical and economic outcomes of node-positive breast cancer with and without postmastectomy radiation therapy (PMRT).

A Markov process was constructed to project the natural history of breast cancer following mastectomy in premenopausal node-positive women. Biannual hazards of local and distant recurrence without PMRT were derived from a large meta-analysis of adjuvant systemic therapy trials for breast cancer. The addition of PMRT reduced the risk of disease relapse by an odds ratio of 0.69. Costs of PMRT ($11,600) and recurrent breast cancer ($4,250 to 16,200/year) were estimated from available literature. The model projected number of recurrences, relapse-free and overall survival, and costs to 15 years, using a discount rate of 3%. Cost-effectiveness ratios were calculated per incremental year of life and quality-adjusted year of life gained. One- and two-way sensitivity analyses were performed to determine the sensitivity of results to clinical and economic assumptions.

The model projected 15-year relapse-free survival of 52% and 43% with and without PMRT, respectively. Overall survival was increased from 48% to 55% with PMRT, resulting in an incremental 0.29 years of life gained per subject. PMRT increased 15-year costs from $40,800 to $48,100. Cost per year of life gained was $24,900, or $22,600 when survival was adjusted for quality of life. Results of the model were relatively sensitive to radiation therapy cost and breast cancer relapse risk.

This analysis suggests that PMRT offers substantial clinical benefits achieved in a cost-effective manner, with an average cost per year of life gained of $24,900. Results of the model were robust under a wide range of clinical and economic parameters.