Does the body mass index impact lymph node yield for colorectal cancer resection, and does operative approach influence this: a review of bi-national colorectal cancer audit database

Background: Operating on an obese patient is technically more challenging. This study aimed to determine whether there was any correlation between lymph node (LN) harvesting and patient's BMI, and how the operative approach influences this. Methods: A retrospective analysis of the bi-national colorectal cancer audit (BCCA) database from 2008 to 2018 was performed. Results: In the analysis of the correlation between operative approach and number of lymph nodes, data on 22 963 patients were analyzed. The operative approach did not lead to a significant difference in the number of lymph nodes yielded, except for proctocolectomy and low anterior resection where laparoscopic approach yielded greater lymph nodes than open approach. Linear regression of BMI and number of lymph nodes harvested for each operation based on 3986 patients showed that BMI largely does not impact the lymph node yield. The exception was open left hemicolectomy/sigmoid colectomy and laparoscopic high anterior resection, where a unit increase in BMI led to a reduction in the number of lymph nodes harvested. However, the regression coefficient and reduction in number of lymph nodes were low (r(2) = 0.11, r(2) = 0.0108 and 0.41, 0.18 lymph nodes). Conclusion: In colorectal cancer operations, the number of lymph nodes removed is largely not impacted by the patient's body mass index, regardless of which operative approach is taken.