Cost-effectiveness of adjuvant chemotherapy for curatively resected gastric cancer with S-1.
BACKGROUND
The effectiveness of specific regimens of adjuvant therapy for gastric cancer has not been verified by large clinical trials. Recently, several large trials attempted to verify the effectiveness of adjuvant therapy. The Adjuvant Chemotherapy Trial of TS-1 for Gastric Cancer in Japan, a randomized controlled trial of adjuvant S-1 therapy for resected gastric cancer, demonstrated significant improvement in overall and relapse-free survival, compared to surgery alone. To evaluate value for money of S-1 therapy, cost-effective analysis was carried out.


METHODS
The analysis was carried out from a payer's perspective. As an economic measure, cost per quality-adjusted life-year (QALY) gained was estimated. Overall survival was estimated by the Kaplan-Meier method, up to 5-year observation. Beyond this period, it was simulated by the modified Boag model. Utility score is derived from interviews with sampled patients using a time trade-off method. Costs were estimated from trial data during observation, while in the period beyond observation they were estimated using simulation results. To explore uncertainty of the results, qualitative and stochastic sensitivity analyses were done.


RESULTS
Adjuvant S-1 therapy gained 1.24 QALYs per patient and increased costs by $3,722 per patient for over lifetime (3% discount rate for both effect and costs). The incremental cost-effectiveness ratio (95% confidence intervals) for over lifetime was estimated to be $3,016 ($1,441, $8,840) per QALY. The sensitivity analyses showed the robustness of these results.


CONCLUSIONS
Adjuvant S-1 therapy for curatively resected gastric cancer is likely cost-effective. This therapy can be accepted for wide use in Japan.
The Institute of Healthcare Technology Assessment, 2-24-10, Shomachi, 770-0044, Tokushima, Japan. akih@k3.dion.ne.jp.
Akinori
A
Hisashige
Mitsuru
M
Sasako
Toshifusa
T
Nakajima
D000328:Adult; D000368:Aged; D000964:Antimetabolites, Antineoplastic / Q000191:economics* / Q000627:therapeutic use*; D017024:Chemotherapy, Adjuvant; D003131:Combined Modality Therapy; D003362:Cost-Benefit Analysis; D004338:Drug Combinations; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010094:Oxonic Acid / Q000191:economics* / Q000627:therapeutic use*; D019057:Quality-Adjusted Life Years; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000191:economics* / Q000401:mortality / Q000473:pathology / Q000601:surgery; D005641:Tegafur / Q000191:economics* / Q000627:therapeutic use*; D016896:Treatment Outcome
D000964:Antimetabolites, Antineoplastic; D004338:Drug Combinations; C079198:S 1 (combination); D005641:Tegafur; D010094:Oxonic Acid