Lymph node size as a simple prognostic factor in node negative colon cancer and an alternative thesis to stage migration.

Background: Stage migration is an accepted explanation for the association between lymph node (LN) yield and outcome in colon cancer. To investigate whether the alternative thesis of immune response is more likely, we performed a retrospective study.

Methods: We enrolled 239 cases of node negative cancers, which were categorized according to the number of LNs with diameters larger than 5 mm (LN5) into the groups LN5-very low (0 to 1 LN5), LN5-low (2 to 5 LN5), and LN5-high (≥6 LN5).

Results: Significant differences were found in pT3/4 cancers with median survival times of 40, 57, and 71 months (P = .022) in the LN5-very low, LN5-low, and LN5-high groups, respectively. Multivariable analysis revealed that LN5 number and infiltration type were independent prognostic factors.

Conclusions: LN size is prognostic in node negative colon cancer. The correct explanation for outcome differences associated with LN harvest is probably the activation status of LNs.