Phase II study of induction gemcitabine and S-1 followed by chemoradiotherapy and systemic chemotherapy using S-1 for locally advanced pancreatic cancer.

PURPOSE: S-1 has systemic activity for locally advanced pancreatic cancer (LAPC). Here, the efficacy and safety of induction gemcitabine (GEM) and S-1 (GS) followed by chemoradiotherapy (CRT) and systemic chemotherapy using S-1 for LAPC were assessed.

METHODS: The treatment consisted of four cycles of induction GS (S-1 60, 80, or 100 mg/day based on body surface area for 14 days every 3 weeks plus GEM 1000 mg/m(2) on days 8 and 15), followed by S-1 (80, 100, or 120 mg/day based on body surface area on days 1-14 and 22-35) and concurrent radiotherapy (50.4 Gy in 28 fractions). Maintenance chemotherapy with S-1 was started 1-4 weeks after CRT until disease progression or unacceptable toxicity was observed. The primary endpoint was 1-year survival.

RESULTS: A total of 30 patients with LAPC were enrolled. The median survival and progression-free survival were 21.3 and 12.7 months, respectively. Overall survival rates at 1, 2, 3, and 4 years were 73.3, 36.7, 23.3, and 16.7%, respectively. The median survival of 23 patients who received CRT was 22.9 months, with a 3-year survival rate of 30.4%. The two most common grade 3 or 4 adverse events during induction GS were neutropenia (63.3%) and biliary tract infection (20%). Toxicities during CRT or maintenance chemotherapy were generally mild.

CONCLUSIONS: This regimen was feasible and highly active resulting in encouraging survival in patients with LAPC. Further investigations are warranted to elucidate the effectiveness of this treatment strategy in future studies. Clinical trials information: UMIN000006332.