Lymph node harvests directly influence the staging of colorectal cancer: evidence from a regional audit

To assess the quality of histopathology reporting and accuracy of Dukes's staging of colorectal cancers in the former South Western Health region and to determine the impact of numbers of lymph nodes examined on stage ascription.

Histopathology reports of colorectal cancer for 1993-7 were analysed. Completeness was assessed regarding reported numbers of lymph nodes examined, numbers found positive, Dukes's stage, and ICD9 code. Numbers of lymph nodes examined, numbers found positive, and Dukes's stage were recorded. Results from one hospital known to have high standards of reporting were compared with those from elsewhere.

In total, 629 reports were examined from the reference hospital and 918 from elsewhere. Fewer than one in 20 (4.3%) reports from the reference hospital were incomplete, compared with a third (36.1%) elsewhere. The average number of nodes examined for each case at the reference hospital was 18.81 and 6.41 elsewhere. The average number of positive nodes for each case was 2.47 at the reference hospital and 1.15 elsewhere. The proportion of Dukes's stage C cases was significantly higher at the reference hospital than elsewhere. Ascertainment of Dukes's stage C cases was related to number of lymph nodes examined, with optimal ascertainment levels when at least 10 and fewer than 15 nodes were examined.

Standards of histopathology reporting, and ascertainment of Dukes's stage C, were significantly higher at the reference hospital. Variations in ascertainment levels of Dukes's stage C disease mainly resulted from variations in the numbers of lymph nodes examined.