Introduction : Lymph node metastasis in pancreatic cancer has been already known to affect the prognosis significantly. Although there are few studies on lymph nodes located adjacent to the tumor, the number of subjects was too small or the results was not clear. Therefore, this study aims to investigate the impact of peritumoral lymph node (PTLN) on the survival outcome of pancreatic cancer patients.

Methods : Medical records of 506 patients who were performed radical resection for pancreatic ductal adenocarcinoma from 2012 to 2018 were reviewed. The PTLN was defined as the lymph node adjacent to the main lesion and others as the regional lymph node (RLN).

Results : Of 506 patients, N0 was 176 (34.8%), N1 was 237 (46.8%), and the remaining 93 (18.3%) were N2. Of these, 112 patients (22.1%) were metastasis in PTLN. The metastatic lymph nodes were subdivided according to the metastasis of PTLN; N0 group without lymph node metastasis; N0+PTLNM group which was classified as N1 because of PTLN metastasis; N1 group. When the survival results of each group were compared, there was no significant difference between N0 and N0+PTLNM (2-year survival rate: 69.4% vs. 73.8%, p=0.488). On the other hand, N0+PTLNM and N1 showed statistically significant differences (73.8% vs. 46.7%, p<0.001).

Conclusions : The metastasis in PTLN has not a significant effect on survival outcome, rather it is concerned for the overstaging if the metastatic PTLN is regarded as RLN. Therefore, the reconsideration is needed for current staging system that regards PTLN as other lymph nodes.