SAN ANTONIO—Routine use of radiation therapy after breast-conserving surgery is a cost-effective strategy for improving outcome in breast cancer, a computerized decision-analysis study suggest.
Radiation therapy adds $10,724 to the cost of conservation, which translates into a cost of $30,805 per quality-adjusted life year, well within the range of cost effectiveness established for medical therapies, James A. Hayman, MD, said at his poster presentation.
Dr. Hayman and his colleagues at Dana-Farber and the Medical College of Virginia assessed cost effectiveness in a theoretical cohort of 60-year-old women followed for 10 years after treatment for early-stage breast cancer.
"Routine radiotherapy following conservative surgery has been shown to reduce the incidence of local recurrence, improve quality of life, and reduce costs associated with salvage therapy," said Dr. Hayman, formerly a resident at the Joint Center for Radiation Therapy and currently clinical assistant professor of radiation oncology at the University of Michigan.
Do Benefits Justify Costs?
He noted that the impact of radiation therapy on survival is unclear, but there is an increased risk of toxicity, as well as increased cost and inconvenience to the patient. "We wanted to find out whether the benefits of routine radiation therapy following conservation justify its costs," he said.
The analysis relied on assumptions based on data derived from the NSABP B-06 study. The investigators assumed that radiation therapy would reduce the incidence of local recurrence by 75%, have no impact on overall survival, improve quality of life, and reduce future salvage costs.
They assumed that local recurrence after radiation therapy and breast conservation would be managed by mastectomy, and that patients initially treated by breast conservation alone would be managed in equal numbers by mastectomy and by radiation plus surgery in the event of local recurrence.
Benefits Expressed in QALYs
Assessment of nonmetastatic health status was based on data collected on 97 actual breast cancer patients. Metastatic health status was based on expert judgment. Cost estimates were derived from Medicare charges, ratios of costs to charges, and relative value units. Benefits were expressed in quality-adjusted life years (QALYs).
The median cost for radiation therapy plus surgery was $28,147, compared with $17,423 for breast-conserving surgery alone. The median benefit of the two strategies was 7.19 and 6.84 QALYs, respectively, for a difference of 0.35. A comparison of the cost difference and the benefit difference resulted in a cost for radiation therapy of $30,805 per QALY.
"This cost is well within the accepted range for cost effectiveness, which is currently felt to be less than $50,000 per QALY," Dr. Hayman said.
The model was sensitive for variations in the cost of radiation therapy; that is, if a higher estimate, in the $30,000 range, was used, the therapy proved not to be as cost effective. Similarly, eliminating patient fear of recurrence as a quality of life factor pushed the cost outside the accepted range.
The model was not sensitive, however, to variations in estimated rates of local recurrence with and without radiation therapy (5% and 20% vs 10% and 30%). Neither did using different estimates of the cost of salvage therapy ($6,000 vs $30,000) affect the model. The introduction of a 2% survival advantage with radiation therapy lowered the cost per QALY to $29,942.
