Comparing cost/utility of giving an aromatase inhibitor as monotherapy for 5 years versus sequential administration following 2-3 or 5 years of tamoxifen as adjuvant treatment for postmenopausal breast cancer.
BACKGROUND
Several studies have shown aromatase inhibitors administered as monotherapy or sequentially to tamoxifen to improve relapse-free survival in postmenopausal women with early breast cancer. Any difference in cost/utility between the strategies may be of importance to therapy selection.


METHODS
Cost/utility was compared between the different regimens based on the theoretical assumption that costs, benefits and side-effects were similar for each drug and independent of whether it was administered as monotherapy or sequentially.


RESULTS
Tamoxifen for 2-3 years followed by an aromatase inhibitor for 3 or 2 years provided the lowest cost/quality-adjusted life years (QALY) estimates, while administration of an aromatase inhibitor subsequent to 5 years on tamoxifen provided the highest values. The difference between strategies increased with patient age. Cost/QALY estimates were sensitive to an increase in hip fracture risk and to cost reductions due to relapse prevention. Adding oral bisphosphonates increased costs moderately.


CONCLUSIONS
While tamoxifen for 2-3 years followed by an aromatase inhibitor provided the lowest cost/QALY estimates, a further improvement of relapse-free survival of 1% if the aromatase inhibitor is given up front provides an acceptable cost/QALY. In contrast, additional benefits achieved by administering an aromatase inhibitor subsequent to 5 years of tamoxifen provided unacceptable costs.
Lønning
P E
PE
Section of Oncology, Institute of Medicine, University of Bergen, Haukeland University Hospital, Bergen, Norway. per.lonning@helse-bergen.no
D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage* / Q000191:economics; D047072:Aromatase Inhibitors / Q000008:administration & dosage* / Q000191:economics; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000191:economics / Q000517:prevention & control; D017024:Chemotherapy, Adjuvant / Q000191:economics; D003362:Cost-Benefit Analysis; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D018803:Models, Economic; D017698:Postmenopause; D016032:Randomized Controlled Trials as Topic; D055502:Secondary Prevention; D013629:Tamoxifen / Q000008:administration & dosage / Q000191:economics
D018931:Antineoplastic Agents, Hormonal; D047072:Aromatase Inhibitors; D013629:Tamoxifen