We postulated that lymph node (LN) harvest and LN size are influenced by immunologic effects.
To investigate this hypothesis, we performed a retrospective analysis of 170 node-negative colon cancer cases to evaluate the density of intratumoral T lymphocytes (ITLs). CD3- and CD8-positive T cells were counted using a digital system.
The ITL density was significantly increased in cases with sufficient LN harvest and high numbers of LNs larger than 5 mm (LN5). High ITL numbers were associated with improved cancer-specific survival. The analysis of the immune score revealed a significantly different cancer-specific outcome (P = .024), with no cancer-related death in the group with the highest score. The immune score and tumor budding were independently prognostic.
ITL density is independently prognostic and associated with LN harvest and LN size. The immune response is very likely the true explanation for the known prognostic effect of the LN harvest in colon cancer.