Lymph node retrieval in colorectal cancer resection specimens: national standards are achievable, and low numbers are associated with reduced survival
The current guidelines identify the retrieval of at least 12 lymph nodes as crucial for accurate staging of colorectal cancer. We set out to review our figures from a single centre to see whether this standard has been met, and to examine for factors which may influence the number of lymph nodes retrieved. The influence of a low lymph node harvest on survival in patients with Dukes' A and B cancers was specifically investigated.Data were collected from all patients with colorectal cancer undergoing resectional surgery from our prospectively compiled database between June 1998 and May 2007. A multivariate analysis was performed to identify factors resulting in low lymph node yields in those patients undergoing formal resection. Survival analyses were performed in patients with Dukes' A and B cancers to assess whether a low lymph node yield negatively impacted on survival.A total of 2449 patients underwent formal resection and were included in the analysis. The median lymph node retrieval was 13 nodes (range 0-136). On multivariate analysis, preoperative chemo-radiotherapy, operation type, specimen length and patient age all independently influenced lymph node retrieval. Patient gender, ethnicity, operative mode, operative team and consultant presence had no influence. Survival in patients with Dukes' A and B cancers was significantly reduced if <12 nodes were sampled.As a unit, we are achieving the national standard for lymph node harvest. This standard was maintained whether the surgeon performing the surgery was a consultant or a trainee, and also when the surgery was performed in the emergency setting. These data support the concept of 12 nodes being required for accurate staging.