Lymphatic Invasion is an Independent Prognostic Factor in Pancreatic Cancer Patients Undergoing Curative Resection Followed by Adjuvant Chemotherapy with Gemcitabine or S-1

Background/Aims: The objective of this retrospective Study was to clarify prognostic factors in pancreatic cancer patients undergoing curative resection. followed by adjuvant chemotherapy with gemcitabine or S-1. Methodology: Both overall survival (OS) and recurrence-free survival (RFS) were examined in 122 pancreatic cancer patients who underwent curative surgery and received adjuvant gemcitabine, or S-1 after surgery between 2005 and 2014. Results: When the length of OS was evaluated according to the log-rank test, significant differences were observed in lymphatic invasion and the T status. Univariate and multivariate Cox's proportional hazard analyses demonstrated that lymphatic invasion was the only significant independent prognostic factor for both OS and: RFS. The 5-year OS was 30.1% in the lymphatic invasion-negative group and 12.1% in the lymphatic invasion-positive group (p<0.001). Moreover, the 5-year RFS was 20.5% in the lymphatic invasion-negative group and 10.4% in the lymphatic invasion-positive group (p=0.006). Conclusions: Lymphatic invasion is the most important prognostic factor for OS and RFS in patients with pancreatic cancer who undergo curative resection followed by adjuvant chemotherapy The present results suggest that adjuvant chemotherapy is not sufficient, especially in patients with risk factors. Such patients should be evaluated as a target group for clinical trials of novel treatments.