Cost-effectiveness assessment of lumpectomy cavity boost in elderly women with early stage estrogen receptor positive breast cancer receiving adjuvant radiotherapy

Background and purpose: Breast radiotherapy (RT) for elderly women with estrogen receptor positive early stage breast cancer (ER+ESBC) improves local recurrence (LR) rates without benefitting overall survival. Breast boost is a common practice, although the absolute benefit decreases with age. Consequently, an analysis of its cost-effectiveness in the elderly ESBC populations is warranted.

Material and methods: A Markov model was used to compare cost-effectiveness of RT with or without a boost in elderly ER+ESBC patients. The ten-year probability of LR with boost was derived from the CALGB 9343 trial and adjusted by the hazard ratio for LR from boost radiotherapy trial data, yielding the LR rate without boost. Remaining parameters were estimated using published data.

Results: Boost RT was associated with an increase in mean cost ($7139 vs $6193) and effectiveness (5.66 vs 5.64 quality adjusted life years; QALYs) relative to no boost. The incremental cost-effectiveness ratio (ICER) for boost was $55,903 per QALY. On one-way sensitivity analysis, boost remained cost-effective if the hazard ratio of LR with boost was <0.67.

Conclusions: Boost RT for ER+ESBC patients was cost-effective over a wide range of assumptions and inputs over commonly accepted willingness-to pay-thresholds, but particularly in women at higher risk for LR.