Harvest of lymph nodes in colorectal cancer depends on demographic and clinical characteristics of the patients.

Purpose: This study aims to study the impact of clinical factors on the lymph node sampling in a large cohort of patients with colorectal cancer.
Methods: A colorectal cancer database of 2298 patients in Queensland, Australia, was established. Zero-inflated regression method was used to model positive lymph node counts given the number of lymph nodes examined, with patient's demographic and clinical factors as covariates in the model. Sensitivity and survival analyses were performed to illustrate the applicability of the recommendation of the minimum number of lymph nodes need to be pathologically examined.
Results: Younger patients with a larger sized tumour located at the left colon or rectum require fewer lymph nodes to be pathologically examined. Overall, 45.9% of the patients require eight or nine lymph nodes and 31.5% needs ten or 11 lymph nodes to be harvested for pathological examination. A simple formula could be used to obtain the minimum number of lymph node sampling required in patients with colorectal cancer based on patients' age as well as site and dimension of the cancer.
Conclusions: The findings provide practical information about that the minimum number of lymph nodes that could be harvested at the time of collection of lymph nodes for pathological examination for patients with colorectal cancer. The minimum number of lymph nodes harvested depends on demographic (age) and clinical (location and dimension of cancer) characteristics of the patients with colorectal cancer.