Purpose: Nodal yields from resected colorectal cancers vary greatly. This study sought to determine what patient, tumor, and management factors influence the number of nodes retrieved and to determine if the extent of lymphadenectomy affects stage allocation and influences survival.
Patients and methods: Retrospective study of the nodal yields of 7,062 surgically resected colorectal cancer patients for whom colorectal pathology minimum data sets had been collected. The percentage of patients diagnosed as stage III was compared across nodal yield categories. A threshold for an adequate lymphadenectomy was defined as retrieval of 12 nodes. Binary logistic regression was used to determine factors associated with obtaining an adequate lymphadenectomy.
Results: Median nodal yields increased over the study period from 7 (interquartile range [IQR], 4 to 11) in 1995 to 13 (IQR 8 to 19) in 2003. There was no difference in yield by cancer site or sex, but yields were lower in older patients. Yields increased with increasing local invasion and stage of tumor. The percentage of patients diagnosed as stage III increased as yields increased. Five-year survival was lower in those patients who did not have an adequate lymphadenectomy. Adequate lymphadenectomy was significantly more likely in patients with advanced tumors and when the surgery and pathology was undertaken by a specialist. Older patients were significantly less likely to receive an adequate lymphadenectomy.
Conclusion: Variations in nodal yield are due to idiosyncratic patient and tumor characteristics and differences in the quality of surgery and pathology undertaken. Adequate lymphadenectomy is essential to ensure correct stage allocation and optimal survival.