The incidence rate of biliary tract cancer (BTC) in the Japanese population exceeds that in the US, European, and East Asian populations. In 2015, approximately 27,000 cases of BTC, the eighth most frequent cause of mortality from cancer, occurred in Japan [
1]. Well-known risk factors for BTC include biliary tract diseases, such as cholelithiasis, and inflammation of the gallbladder and biliary tract. Recently, there has been much concern about the high incidence of BTC in workers at printing presses because of their exposure to 1,2-dichloropropane, which has been implicated as a possible cause of BTC.
Gemcitabine and fluoropyrimidine drugs are commonly used as systemic chemotherapy for advanced BTC. In addition, a meta-analysis of 112 clinical trials concluded that combination treatment with gemcitabine and a platinum agent was effective for the treatment of BTC [
2]. Furthermore, two randomized controlled trials (RCTs) (UK ABC-01 [
3]) demonstrated that gemcitabine plus cisplatin (GC combination therapy) was an effective treatment for BTC. A phase III trial (UK ABC-02 (4)) was carried out in the UK to investigate the clinical efficacy and safety of GC combination therapy (1000 mg/m
2 of gemcitabine + 25 mg/m
2 of cisplatin on days 1 and 8, repeated every 3 weeks) versus gemcitabine alone (G monotherapy) (1000 mg/m
2 of gemcitabine on days 1, 8, and 15, repeated every 4 weeks) on the primary endpoints of overall survival (OS) and progression-free survival. In the ABC-02 study [
4], the treatments resulted in median OS times of 11.7 and 8.1 months, respectively, and progression-free survival times of 8 and 5 months, respectively. Using the same protocol as the ABC-02 study [
4], an RCT called the BT-22 trial was conducted in Japan [
5]. The results indicated that the median OS times for GC combination therapy and G monotherapy were not significantly different (11.2 and 7.7 months (
p = 0.139), respectively), whereas the progression-free survival times were not significantly different (5.8 and 3.7 months (
p = 0.077), respectively). These findings agreed with the results of the ABC-02 study [
4]. The updated guidelines for Japan, therefore, recommend GC combination therapy as first-line treatment for advanced BTC.
Roth et al. [
6] evaluated the cost utility of GC combination therapy in the USA using the results of the ABC-02 study [
4] and concluded that GC combination therapy was more cost-effective than G monotherapy as per the accepted standards of willingness to pay (WTP) in the USA (50,000 US dollars per quality-adjusted life year (QALY) gained).
Using the results of the BT-22 trial [
5], this study assessed the cost-effectiveness of GC combination therapy compared to that of G monotherapy for the treatment of BTC from the perspective of healthcare payers in Japan.