Cost-effectiveness of switching to exemestane versus continued tamoxifen as adjuvant therapy for postmenopausal women with primary breast cancer.
BACKGROUND
Sequential tamoxifen/exemestane therapy reportedly improves disease-free survival in women with primary breast cancer compared with continued tamoxifen therapy. The objective of the current study was to assess the cost-effectiveness of switching to exemestane after 2 to 3 years of tamoxifen versus continued tamoxifen in postmenopausal women with primary breast cancer for a total of 5 years of adjuvant therapy.


METHODS
A Markov model based on the Intergroup Exemestane Study (IES) population compared switching to exemestane versus continued tamoxifen for 2.5 years of therapy and 5 years of postadjuvant therapy follow-up. Disease progression and hazards ratios (HR) for recurrence and survival were determined from datasets (IES and the Surveillance, Epidemiology, and End Results program of the National Cancer Institute) and from the published literature. An expert panel validated treatment patterns, outcomes, and resource utilization. Direct medical costs were included based on published sources. Cost-effectiveness ratios were determined, and extensive sensitivity analyses were conducted.


RESULTS
Exemestane was found to be more effective than tamoxifen alone with regard to disease-free survival (2.6% absolute improvement), life-years gained (0.1028 LY), and quality-adjusted life-years gained (0.1195 QALY), at an additional cost of 2,889 Can dollars per person over 7.5 years. Incremental cost-effectiveness ratios were 28,119 Can dollars/LY gained and 24,185 Can dollars/QALY gained. The model was most sensitive to distant recurrence HR but was robust to variations in clinical, cost, and utility parameters.


CONCLUSIONS
Switching to adjuvant exemestane after 2 to 3 years of tamoxifen is cost-effective in postmenopausal women with primary breast cancer.
Risebrough
Nancy A
NA
HOPE Research Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
Verma
Shailendra
S
Trudeau
Maureen
M
Mittmann
Nicole
N
D000730:Androstadienes / Q000191:economics* / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000191:economics* / Q000627:therapeutic use; D047072:Aromatase Inhibitors / Q000191:economics* / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy / Q000191:economics* / Q000401:mortality; D003362:Cost-Benefit Analysis; D016527:Drug Costs; D005260:Female; D006801:Humans; D008390:Markov Chains; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000191:economics / Q000517:prevention & control; D017698:Postmenopause; D019057:Quality-Adjusted Life Years; D018426:SEER Program / Q000706:statistics & numerical data; D020845:Selective Estrogen Receptor Modulators / Q000191:economics* / Q000627:therapeutic use; D012680:Sensitivity and Specificity; D015996:Survival Rate; D013629:Tamoxifen / Q000191:economics* / Q000627:therapeutic use
D000730:Androstadienes; D000970:Antineoplastic Agents; D047072:Aromatase Inhibitors; D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen; C056516:exemestane