Factors influencing the number of retrieved lymph nodes after colorectal resection: a retrospective study from a single institute

Accurate diagnosis of lymph node (LN) metastasis is important to determine the staging and consequent treatment of resected colorectal cancer. Therefore, factors influencing the number of retrieved LNs were explored. This study included 400 patients that underwent surgical resection for Stage 0-III colorectal cancer from 2009 to 2014 in Kochi Medical School. In all cases, surgeons retrieved the LNs within the resected mesentery immediately after the operation without fixation. Age, gender, body mass index (BMI), American Association Anesthesiologist (ASA) scores, tumor locations, maximum tumor diameters, nodal status, and pathological tumor types were extracted as patient and tumor factors. The extent of LN dissection and surgical approaches (laparoscopic or laparotomy) were extracted as operative factors. Multivariate regression analysis was performed to identify independent predictive factors for LN number retrieved, after potential influential factors were explored by univariate analysis. As results, we found that the median number of retrieved LNs was 13, ranging from 1 to 50. Approximately 60% of the patients thus received an adequate examination (LN number of 12 or more). Multivariate analysis using the remaining factors of univariate analysis identified BMI, tumor diameter, nodal status, and extent of dissection as independent predictive factors for the number of retrieved LNs (P < 0.05). If any or all these factors are present, a vigorous search for LNs using additional measures, such as visual enhancement and fat dissolution method, should be considered.