Lymph node harvest in colorectal adenocarcinoma specimens: the impact of improved fixation and examination procedures

A review of 1050 pathology reports from colorectal adenocarcinoma specimens examined at the Department of Pathology, Sørlandet sykehus HF, Kristiansand, Norway during the period 1995-2006 revealed a poor performance of most doctors concerning lymph node harvest. A mean of 8.1 nodes per specimen (range 12.3-2.1) and a mean proportion of 22.3% of specimens with ≥12 lymph nodes (range 47.1-0%) were found. A small pilot study was undertaken in 2007 to evaluate the effect of prolonged formalin fixation and the use of a special lymph node fixative [glacial acetic acid, ethanol, water and formaldehyde (GEWF) solution] with regard to the number of retrieved nodes. This showed that one extra day formalin fixation and the use of GEWF solution considerably enhanced the detection of lymph nodes, particularly those of smaller size. Based on these findings, our routines concerning handling of colorectal cancer specimens were changed during 2007. After this time all specimens have been fixed in a mixture of GEWF solution and formalin for at least 48 h and the doctors have been encouraged to find as many lymph nodes as possible. In cases revealing <12 nodes after microscopical examination, the specimens have been re-examined and searched for additional nodes. A review of lymph node retrieval in 423 cases of colorectal cancer during the period 2008-2010 showed that the mean number of nodes per specimen had increased to 16.8 (range 29.0-13.3) and the proportion of specimens with ≥12 nodes to 78.0% (range 96.8-63.6%). Thus, these changes of routines which were easy to implement without significant extra costs have considerably improved lymph node harvest at our department. The use of a special lymph node fixative (e.g. GEWF solution) is highly recommended not only for detection of nodes in colorectal specimens, but also for retrieval of lymph nodes embedded in fat tissue generally.