[The effectiveness of S-1 based sequential chemotherapy as second-line treatment for advanced/recurrent gastric cancer].

Background: We conducted this study to evaluate the efficacy of S-1 combination chemotherapy as second-line treatment for advanced/recurrent gastric cancer that was resistant to S-1 based chemotherapy as first-line treatment.

Patients And Methods: We evaluated patients included in phase II.III clinical trials, that is SPIRITS trial(S-1 vs CDDP +S-1), GC0301/TOP-002(S-1 vs CPT-11+S-1), OGSG0002(S-1+CPT-11)and OGSG0105(S-1+paclitaxel). Eligibility criteria at first-line included; pathologically proven gastric cancer, adequate bone marrow, hepatic, and renal functions, PS 0-2, no prior therapy, life expectancy estimated > or =12 weeks, age 20-75 years and written informed consent. Endpoints were as follows; )PFS in first-line and second-line, )Time to Second Progression(TSP), 3) OS.

Results: Sixty-six patients were evaluable in this study. We classified these patients into 4 groups according to the protocol. A)S-1 alone in first-line and S-1 combination in second-line(n=7), B)S-1 alone in first-line and other drugs in second-line(n=13), C)S-1 combination in first-line and another S-1 combination in second-line(n=33), D) S-1 combination in first-line and other drugs in second-line(n=13). We compared S-1 combination group(A+C)to other drugs group(B+D)in second-line. In first-line, PFS was 157.5 days in group(A+C)and 130 days in group(B +D)(p=0.2749). In second-line, PFS, TSP and OS were as follows; 72.5, 256.5, 473 days in group(A+C)and 56, 201.5, 398.5 days(PFS; p=0.0806, TSP: p=0.0718, OS: p=0.0204)in group(B+D), respectively. With regards to adverse events, group(A+C)in first-line showed higher frequency in grade 3/4 leukopenia(10%), febrile neutropenia(5%)and grade 3 diarrhea(10%)than group(B+D). In second-line, group(B+D)showed grade 3/4 leukopenia (12%)and neutropenia(8%)than group(A+C). There were no treatment-related deaths.

Conclusion: These results indicate that S-1 combination chemotherapy is efficient as second-line for advanced/recurrent gastric cancer that got resistant to S-1 based chemotherapy as first-line.