The clinical usefulness of a new fat-dissociation method to detect lymph nodes from surgically resected specimen in colorectal cancer: Prospective randomized study

Abstract

Background: Pathological examination is essential to determine the cancer stage in col‐orectal cancer (CRC) patients, and histological examination of lymph nodes plays a pivotal role in the staging process. We previously reported a new fat‐dissociation method (FM) to detect lymph nodes from surgically resected mesentery. It can reduce a fat volume of the mesentery and visualize a structure of vessels and lymph nodes. In this study we examined the effectiveness of the FM compared with a conventional palpation method inCRC. Methods: A single center, open‐label, randomized controlled study was performed at Osaka International Cancer Institute (OICC) in Japan from January, 2014, to December, 2014. Randomization was done via a computer‐generated permuted‐block sequence, and was stratified by surgical procedures and the dissection area of lymph nodes (ie, D2 or D3). Primary endpoint was set at the time to search lymph nodes. Secondary endpoint was set at the number of lymph nodes and 5‐year overall survival (OS). Results: 130 patients were enrolled to this study and randomly assigned in a one to one ratio: 65 to the FM group and 65 to the conventional palpation (CP) group. Searching time were 15.9 (60.6) minutesinthe FMgroup and 45.1 (61.5) minutesin the CP group (P < 0.001). In CP group there was correlation between BMI and searching time (P=0.047). Numbers oflymph nodes were 21.5 (61.9) in theFM group and 19.6 (61.4) in the CP group (P = 0.546). In right‐side CRC, the number of lymph nodes was more intheFM group (32.664.5) than theCPgroup (21.762.6)(P=0.030). 5‐year OS rate was 87%in the CPgroup and 86%in the FMgroup (P=0.952). Conclusions: A new fat‐dissociation method could reduce the time for searching lymph nodes without reducing number of lymph node. It is effective in high BMI patients and right‐side CRC.