The effect of total lymph nodes removed and the lymph node ratio on overall survival in resected pancreatic cancer.

Abstract

371 Background: Previous studies evaluating lymph node status in pancreatic cancer have demonstrated that the ratio of positive nodes to total numbers resected is an important prognostic factor for survival. In our study we sought to see if the total number of nodes removed and lymph node ratio (LNR) would influence overall survival. Methods: A retrospective chart review of 210 patients from July 1998 to July 2011 who underwent resection of pancreatic adenocarcinoma was done. Patients were evaluated for demographic information, neoadjuvant therapy status, surgical margins, pathological stage, total number of lymph nodes retrieved and the number of positive lymph nodes. The LNR was calculated by taking the number of positive lymph nodes to the total number of lymph nodes retrieved. The endpoint evaluated was overall survival (OS). Results: Of the 210 patients, 107 (51%) were male and 103 (49%) were female. The median age was 68. A total of 110 patients had 1 or more positive nodes. The median number of nodes evaluated for all patients was 15 (range 2-51) and the median number of positive lymph nodes was 1. In patients with positive lymph nodes, the median LNR was 0.15 or 15%. For the 210 patients, in univariate analysis, there was a statistically significant association between LNR and overall survival. When the LNR reached >11.2%, patient survival was worse (p=0.018). The total number of nodes removed was not significantly associated with OS for those with positive or negative nodes. However, with multivariable CART analysis, taking into account T stage and surgical margins, LNR had a significant impact on overall survival only for patients who had a R0 resection and T0-T2 disease. If there LNR was > 0, survival was better (p=0.043). Conclusions: In certain GI malignancies, complete evaluation of local lymph nodes is important and changes the survival of patients. In T0-T2 stage pancreatic cancer patients resected with negative margins, outcome is worse if there are positive nodes in these patients. Therefore based on our data, the LNR may be useful for determining the prognosis of early T stage cancer patients.