How many lymph nodes to stage colorectal carcinoma?

This study aimed to establish the number of cassettes that should be filled with lymph nodes to stage a colorectal carcinoma as Dukes's stage C. The records from the Oxford Colorectal Cancer database of all patients diagnosed with Dukes's stage C cancer from late 1988 to early 1993 were reviewed. Each slide of lymph nodes was examined to determine how many slides needed to be looked at to find the first positive lymph node. The resected specimens were not fat cleared but dissected manually in a routine fashion. One hundred and eight slides were retrieved. The mean total lymph node harvest was 8.44 for each patient. Ninety eight patients (90.7%) had positive lymph nodes on the first slide with an average of 3.42 lymph nodes on each slide, of which a mean of 1.82 were positive. For nine patients, two slides were required to make a diagnosis of lymph node involvement, and for one patient the first three slides needed inspection to establish Dukes's stage C. In conclusion, using a routine technique to obtain lymph nodes from colorectal cancer specimens 99% of Dukes's stage C colorectal carcinoma can be found by filling two cassettes with lymph nodes.