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Objective: Stage-specific survival for colon cancer is improved when more lymph nodes are identified in a surgical specimen; a minimum of 12 nodes is considered a quality indicator. The purpose of this study is to determine if treatment with Schwartz solution increases the number of nodes identified compared to manual dissection alone and to identify clinicopathological factors that influence node count.
Design: Prospective cohort
Setting: Academic medical center
Patients: 104 consecutive patients with colorectal cancer who underwent resection.
Interventions: Standard manual lymph node dissection, treatment with Schwartz solution.
Main Outcome Measures: Lymph node count, tumor stage
Results: Schwartz solution method increased the mean number of lymph nodes from 25.1 to 30.7 (p=0.000, 95% CI: 1.96 - 5.24). 98% of these nodes were less than 5mm in size. Only one patient was upstaged from node-negative to node-positive (pN0 to pN1a) and two patients were upstaged from pN1a to pN1b and pN2a to pN2b. The number of specimens with less that 12 nodes decreased from 15 to 9. Increasing age (p = 0.002) , specimen length (p = 0.037), mesenteric fat mass (p=0.000), fat volume (p=0.000), grade (p=0.000), right sided tumor (p=0.02), tumor size (p=0.002), stage (p=0.035), and T-stage (p=0.005) were associated with increased node count. CEA, platelet and white count, open versus laparoscopic resection, surgical volume, tumor type, lymphovascular/ perineural invasion, and lymphocytic response were not associated .
Conclusions: Although Schwartz solution increased node count, only 1 patient was upstaged from node-negative to node-positive. Understaging is unlikely to explain the increase in survival in patients with higher node counts. The number of lymph nodes found is likely a reflection of tumor biology or host-related factors.