Abstract
AIM: This study evaluated the relationship between the relative dose intensity (RDI) and the prognosis to assess the optimal duration of adjuvant chemotherapy for pancreatic cancer. PATIENTS AND METHODS: From 2013 to 2018, 119 patients with pancreatic cancer underwent radical surgery. After excluding five patients who underwent R2 resection, three with stage IV disease, and two with adjuvant chemotherapy other than S-1, 109 cases were evaluated. They were classified into four groups based on the RDI for the total dosage of S-1: group 1: <50%, group 2: 50% to <80%, group 3: 80% to ≤125%, and group 4: >125%. RESULTS: The number of patients in each group were 48, 20, 30 and 11, with median ages of 74, 73, 66 and 74, respectively. Median estimated glomerular filtration rate was 75, 72, 89 and 77 ml/min/1.73 m(2), respectively, demonstrating statistically significant differences. The corresponding median and 5-year overall survival rates were: 378 days and 17.9%; 1,011 days and 35.1%; 1,246 days and 41.6%; 1,389 days and 10.6%. Using group 1 as a reference, the adjusted hazard ratio was 0.39 for group 2, 0.36 for group 3, and 0.30 for group 4; all were statistically significant. CONCLUSION: The higher the RDI of S-1 in adjuvant chemotherapy, the better the overall survival. Therefore, 1 year of adjuvant chemotherapy with S-1 in pancreatic cancer may be preferable to 6 months.