Purpose: Adjuvant chemotherapy decisions for women with early-stage breast cancer are complex. the 21-gene assay, a gene expression profiling test, is validated at predicting distant recurrence-free response in patients with ER+ LN- early-stage breast cancer. This enables chemotherapy to be better targeted at higher risk patients than is possible through the use of Adjuvant! Online (AOL) or clinical judgement alone. However, existing cost-effectiveness analyses of the 21-gene assay have numerous limitations: in particular, they consider a limited range of strategies and do not separately consider intermediate risk patients identified through either AOL or the 21-gene assay. Our objective was to build an Ontario-based cost-effectiveness analysis which comprehensively addresses these limitations.
Method: We built upon a Markov model developed by Tsoi and colleagues, using data from the NSABP B-14 and B-20 clinical trials. We assumed that AOL and the 21-gene assay may be provided separately or sequentially and considered the chemotherapy decision separately for every possible risk group, resulting in 1000 unique strategies for the provision of AOL, the 21-gene assay and chemotherapy.
Result: The 21-gene assay appears cost-effective for all patients, regardless of a patient’s initial AOL risk assessment. The highest ICER is in patients at low AOL risk ($29,000 per QALY), while the 21-gene assay dominates in patients at high AOL risk. Chemotherapy appears cost-effective only in patients at intermediate or high 21-gene assay risk. The highest ICER is in patients at low AOL and intermediate 21-gene assay risk ($64,000 per QALY). Chemotherapy is dominated in patients at low 21-gene assay risk.
Conclusion: The 21-gene assay appears to be cost-effective for all Ontario women with ER+ LN- early-stage breast cancer, regardless of the woman’s initial AOL risk assessment. These results have informed the Ontario Health Technology Advisory Committee’s recent deliberations regarding the funding of the 21-gene assay in Ontario.