Risk factors for 6-month continuation of S-1 adjuvant chemotherapy for resected pancreatic cancer.

Background: The factors which affect the 6-month continuation of adjuvant chemotherapy with S-1 have not been fully evaluated in pancreatic cancer. The objective of this retrospective study was to clarify the risk factors for the discontinuation of S-1 adjuvant chemotherapy after 6 months of treatment.
Methods: The study included patients who underwent curative surgery for pancreatic cancer, were diagnosed with stage II or III disease, had a serum creatinine level ≤1.2 mg/dl and received adjuvant S-1 between June 2007 and March 2014.
Results: Forty patients were eligible for the present study. A comparison of the 6-month continuation stratified by each clinical factor using the log-rank test revealed a significant difference in the creatinine clearance (CCr) between the patients who continued and discontinued the treatment. A CCr of 60 ml/min was regarded as a critical point. The uni- and multivariate Cox's proportional hazard analyses demonstrated that the CCr was the only significant independent predictive factor. The 6-month continuation rate was 70.8 % in the patients with a CCr ≥60 ml/min and was 25.0 % in patients with a CCr <60 ml/min (P = 0.008). The patients with a CCr <60 ml/min developed adverse events more frequently and earlier than those with a CCr ≥60 ml/min.
Conclusions: A CCr < 60 ml/min was a significant risk factor for the 6-month discontinuation of S-1 adjuvant chemotherapy in pancreatic cancer patients, even though the renal function was judged to be normal based on the serum creatinine level. Careful attention is therefore required to improve the S-1 continuation in patients with a CCr < 60 ml/min.