Lymph node harvest as a predictor of survival for colon cancer: A systematic review and meta-analysis

Background and Objectives

The number of lymph nodes found harboring metastasis can be impacted by the extent of harvest. Guidelines recommend 12 lymph nodes for adequate lymphadenectomy to predict long-term oncologic outcomes, yet different cut-offs remain unevaluated. The aim of this review was to determine cut-offs that may predict survival outcomes.

Methods

Medline, Embase, and CENTRAL were systematically searched. Articles were included if they compared overall survival (OS) or disease-free survival (DFS) above and below a lymph node harvest cut-off. Studies solely examining rectal cancer or stage-IV disease were excluded. Pairwise meta-analyses using inverse variance random effects were performed.

Results

From 2587 citations, 20 studies with 854,359 patients (51.9% female, mean age: 68.9) were included, with 19 studies included in quantitative synthesis. A lymph node harvest cut-off of 12 predicted improved five-year OS (7 studies; OR 1.11, 95% CI 1.08–1.14, p<0.00001). A cut-off as low as 7 was associated with improved five-year OS (2 studies; OR 1.16, 95% CI 1.08–1.25, p<0.0001) and DFS (3 studies; OR 1.66, 95% CI 1.32–2.10, p<0.00001). All cut-offs greater than 12 demonstrated improved survival.

Conclusions

A lymph node cut-off of 12 distinguishes differences in five-year oncologic outcomes. Contrarily, lymph node harvests other than 12 have not been rigorously studied and thus lack the statistical power to derive meaningful conclusions compared to the 12-lymph node cut-off. Nonetheless, it is possible that a lymph node harvest cut-offs less than 12 may be adequate in predicting long-term survival. Further prospective study evaluating cut-offs below 12 are warranted.