Cost-effectiveness of adjuvant radiotherapy for older women with early hormone-receptor positive breast cancer

Background: Radiation therapy (XRT) following breast conserving surgery decreases local recurrence at the expense of additional morbidity and treatment costs. However, its utility in elderly women at low risk of recurrence has been questioned. This study assessed the cost-effectiveness of adding XRT to hormonal therapy (HT) in women over 70 with stage I, hormone-receptor positive (HR+) breast cancer after breast conserving surgery. Methods: A decision tree model was used to assess the costs and benefits of XRT + HT versus HT alone in 10,000 women age 70+ with stage I HR+ breast cancer. Using a societal perspective, we considered medical costs and quality of life effects of initial treatment, recurrences, and metastatic disease as well as long-term XRT-associated complications including breast fibrosis, chronic pneumonitis and cardiac disease. Probabilities of recurrence and death were modeled on recent clinical trial results, while toxicity probabilities were taken from literature review. The primary health outcome was incremental quality-adjusted life years (QALYs) gained. One-way and probabilistic sensitivity analyses (PSA) were performed to assess the sensitivity of model results and conclusions to various parameter estimates. Results: In the base-case scenario, the incremental cost-effectiveness ratio (ICER) for the addition of XRT was $923,017/QALY. The ICER was highly sensitive to variations in utility weights, particularly those reflecting patient preferences for initial treatment with or without XRT and those reflecting the decrement in quality of life resulting from breast fibrosis. In PSA, XRT was associated with lower quality-adjusted life expectancy at higher cost in 58% of simulations. Conclusions: In women over 70 with stage I HR+ breast cancer, the addition of XRT to HT is not cost-effective at a willingness-to-pay threshold of $100,000/QALY, and is associated with little or no improvement in quality-adjusted life expectancy. Providers should be aware that the cost-effectiveness of XRT in this population is strongly influenced by patient preferences surrounding recurrence and toxicity risks, and should weigh these factors when making shared decisions with patients.