Second evaluation of the mesenteric tissue after ethanol fixation improved the total and metastatic number of lymph nodes in colorectal resections

Abstract

Context: There is a correlation between prognosis of the colorectal carcinomas and the number of retrieved and metastatic lymph nodes (LNs) from mesentery/mesorectal region. At least 12 LNs must be sampled for accurate evaluation of patients. A number of factors related to surgeon, pathologist, patient and disease could affect the total LN number. For maximizing LN yield, pathologist can use ancillary methods, as fat clearance and special solutions. Aims: This study investigates the effect of second evaluation after ethanol fixation on total and metastatic LN number and assesses factors that influence the dissected LN number. Materials and Methods: 177 colorectal resections were refixed with ethanol for a night, after standard LN sampling. Mesentery/mesorectal tissue was reevaluated for missed LNs. Results were statistically analyzed, P values <0.05 were considered significant. Results: Mean LN number increased from 26 to 30 (median: 20 to 25, P < 0.001) after ethanol fixation. Fourteen cases had additional metastatic LNs after reevaluation of the fat tissue and 5 of them upstaged. 22.5% (44/177) of the patients had <12 LNs before ethanol fixation and this decreased to 14.3% (26/177) after ethanol fixation. Resection type and length, tumor localization, size and histologic degree, pT and neoadjuvant therapy (P < 0.001) had an impact on the LN number (P = 0.034 for histologic degree, P = 0.02 for pT, P < 0.001 for others). Conclusions: Carrying out a second evaluation with ethanol fixation increased total and metastatic LN number and could lead upstage of pN. Ethanol fixation is cost-effective, easy accessible and applicable method; it may improve accuracy of LN assessment and staging, which are important for patients' outcome.