Cost-effectiveness of letrozole versus tamoxifen as initial adjuvant therapy in postmenopausal women with hormone-receptor positive early breast cancer from a Canadian perspective.
BACKGROUND
In the primary core analysis of BIG 1-98, a randomized, double-blind trial comparing 5 years of initial adjuvant therapy with letrozole versus tamoxifen in postmenopausal women with hormone receptor-positive (HR+) early breast cancer, letrozole significantly improved disease-free survival by 19% and reduced the risk of breast cancer recurrence by 28% and distant recurrence by 27%.


METHODS
A Markov model was used to estimate the incremental cost per quality-adjusted life year (QALY) gained with 5 years of initial adjuvant therapy with letrozole versus tamoxifen from a Canadian healthcare system perspective. Probabilities of recurrence and side effects for tamoxifen were based on published results of BIG 1-98 and other published population-based studies. Corresponding probabilities for letrozole were calculated by multiplying probabilities for tamoxifen by estimated relative risks for letrozole versus tamoxifen from BIG 1-98. Other probabilities, costs of breast-cancer care and treatment of side effects, and health-state utilities were obtained from published studies. Costs and QALYs were estimated over the lifetime of a cohort of postmenopausal women with HR+ early breast cancer, aged 60 years at initiation of therapy, and discounted at 5% annually.


RESULTS
Compared with tamoxifen, letrozole yields an additional 0.368 life-years (12.453 vs. 12.086) and 0.343 QALYs (11.582 vs. 11.239). These benefits are obtained at an additional cost of Can$ 8,110 (Can$ 30,819 vs. Can$ 22,709). Cost per QALY gained for letrozole versus tamoxifen is Can$ 23,662 (95% CI Can$ 15,667-Can$ 52,014).


CONCLUSIONS
In postmenopausal women with HR+ early breast cancer, initial adjuvant treatment with letrozole is cost-effective from the Canadian healthcare system perspective.
Delea
Thomas E
TE
Policy Analysis Inc (PAI), Brookline, MA 02445, USA. tdelea@pai2.com
El-Ouagari
Khalid
K
Karnon
Jonathan
J
Sofrygin
Oleg
O
D018931:Antineoplastic Agents, Hormonal / Q000191:economics* / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy*; D002170:Canada; D017024:Chemotherapy, Adjuvant / Q000191:economics; D003362:Cost-Benefit Analysis; D016527:Drug Costs; D005260:Female; D006801:Humans; D000077289:Letrozole; D008390:Markov Chains; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy*; D009570:Nitriles / Q000191:economics* / Q000627:therapeutic use; D017698:Postmenopause; D019057:Quality-Adjusted Life Years; D013629:Tamoxifen / Q000191:economics* / Q000627:therapeutic use; D014230:Triazoles / Q000191:economics* / Q000627:therapeutic use
D018931:Antineoplastic Agents, Hormonal; D009570:Nitriles; D014230:Triazoles; D013629:Tamoxifen; D000077289:Letrozole