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Comparing the treatment outcomes between unresectable and recurrent cases receiving gemcitabine and S-1 combination chemotherapy in patients with advanced biliary tract cancer: Pooled analysis of two prospective studies.

331 Background: We previously conducted two prospective studies (phase II study and randomized phase II study) of gemcitabine (GEM) and S-1 combination chemotherapy. The purpose of this study was to clarify the difference of treatment outcomes between unresectable and recurrent cases receiving GEM/S-1 combination chemotherapy in patients with advanced biliary tract cancer.


METHODS
The data of two prospective studies were combined for the analysis. In these studies, GEM was administered intravenously at a dose of 1,000 mg/m2 over 30 min on days 1 and 15, repeated every four weeks. S-1 was administered orally at a dose of 40 mg/m2 b.i.d. on days 1-14. Tumor response was assessed every two cycles using RECIST version 1.0. The treatment was continued until disease progression, unacceptable toxicity or patient refusal occurred.


RESULTS
Fifty-five unresectable cases and ten recurrent cases were enrolled in this analysis. Patient characteristics were similar between each group except the baseline sum of longest diameter, which was used as a measurement of tumor volume (unresectable 9.0 cm vs recurrent 2.8 cm). Response rates of unresectable and recurrent cases were 25.5% and 40.0%, respectively. Dose intensities of each group were statistically different (gemcitabine 96.8% vs 83.5%, p=0.03; S-1 91.8% vs 75.9%, p=0.03). The median time-to-progressions of unresectable and recurrent cases were 5.7 months and 8.7 months, respectively (p=0.14). The overall survivals of each group were 9.6 months and 16.1 months (p=0.10).


CONCLUSIONS
In recurrent cases, tumor volume was smaller and dose intensity was lower than that of unresectable cases. Recurrent cases showed better treatment outcome comparing to unresectable cases. Therefore, unresectable and recurrent cases should be analyzed separately in the future study.