Method of specimen fixation and pathological dissection of colorectal cancer influences retrieval of lymph nodes and tumour nodal stage

Introduction: There is now evidence that meticulous specimen dissection may 'upstage' around one-quarter of colorectal cancers from node negative to node positive, although there is much debate as to how to achieve this: some authors prefer fat clearance techniques while others have opted for more conventional lymph-node retrieval with manual specimen 'breadknifing' and lymph-node palpation. While fat clearance is probably the optimum technique, it is time-consuming, costly and does not provide rapid diagnostic results. Methods: A prospective pathological study of 50 colorectal cancer resections was conducted with 100 comparison cases, the study group receiving at least an additional 24-h fixation of the mesocolonic or mesorectal fat in 10% aqueous formaldehyde prior to specimen dissection. Results: The percentage of node-negative colorectal cancer was significantly lower in the study group compared with the matched comparison group: (18) 36% compared with (55) 55% of comparison cases. Conclusions: Effective lymph-node retrieval techniques require mesocolic/mesorectal fat to be adequately fixed prior to pathological dissection. This study suggests that satisfactory lymph-node retrieval is possible without fat clearance, provided the mesenteric fat is suitably fixed prior to colorectal cancer specimen dissection. (C) 2000 Harcourt Publishers Ltd.