Most guidelines for hormone receptor (HR)-positive early breast cancer recommend addition of adjuvant chemotherapy for most women, leading to overtreatment, which causes considerable morbidity and cost. There has been recent incorporation of gene expression analysis in aiding decision making. We evaluated the cost-effectiveness of recurrence score (RS)-guided treatment using 21-gene assay as compared with treatment guided by the Adjuvant! Online program (AOL).
A Markov model was developed to compare the cost-effectiveness of treatment guided either by 21-gene assay or by AOL in a 50-year-old woman with lymph node-negative HR-positive breast cancer over a lifetime horizon. We assumed that women classified to be at high risk all received chemotherapy followed by tamoxifen and those classified to be at low risk received tamoxifen only. The model took a health care payer's perspective with results reported in 2008 Canadian dollars ($). Event rates, costs, and utilities were derived from the literature. Both costs and benefits were discounted at 5%. Outcome measures were life years gained, quality-adjusted life years (QALYs), lifetime costs, and incremental cost-effectiveness ratios (ICERs).
For a 50-year-old woman, RS-guided treatment was associated with an incremental lifetime cost of $4,102 and a gain in 0.065 QALY, with an ICER of $63,064 per QALY compared with AOL-guided treatment. ICER increased with increasing cost of 21-gene assay and increasing age of patients. Results were most sensitive to probabilities relating to risk categorization and recurrence rate.
The 21-gene assay appears cost-effective from a Canadian health care perspective.