The influence of nodal size on the staging of colorectal carcinomas

Aims: The reliable identification of node negative colorectal carcinomas (CRCs) has often been linked to the histological examination of a minimum number of lymph nodes. The sizes of the lymph nodes, their metastatic status, and their number were investigated to establish whether these parameters are related, and whether their relation could help in determining the adequacy of staging, Methods: One thousand three hundred and thirty four negative lymph nodes, 189 metastatic lymph nodes, and 43 pericolonic/perirectal tumour deposits measuring greater than or equal to 3 mm from 60 node positive and from 63 node negative patients with CRC were assessed for size, Results: The mean size (SD) of these structures was 4.5 (2.7) mm. The lymph nodes were significantly larger in the CRCs with metastatic nodes (4.7 v 4.3 mm). Involved nodes were significantly larger than negative nodes (6.3 v 4.2 mm), despite the fact that the largest node was less than or equal to 5 mm in one third of node positive CRCs. The examination of the seven largest nodes could have adequately staged 97% of node positive CRCs and 98% of all CRCs. Conclusions: The nodal staging of CRCs is dependent not only on the number of lymph nodes investigated, but also on qualitative features of the lymph nodes assessed, including their size. Lymph nodes are not equivalent and any study neglecting this fact will give grounds for error in the recommendation of a minimum number of nodes for the reliable determination of node negative CRCs. Although pathologists should aim to recover all nodes, a negative nodal status based on only seven nodes can be reliable.