Background: Insufficient lymph node harvest in presumed stage II colon carcinomas can result in understaging and worsened cancer outcomes. The purpose of this study was to evaluate factors affecting the number of lymph node examined, their corresponding impact on cancer outcomes, and the optimal number of examined nodes with reference to the standard of 12.
Materials and methods: We evaluated all patients undergoing surgery alone for stage II colon cancer included in our colorectal cancer database since 1976.
Results: A total of 901 patients were included. Mean follow-up exceeded 8 years. The individual pathologist had no statistically significant association with the number of lymph nodes examined. Harvest of at least 12 nodes was related to surgery after 1991 (85% vs 69%, P < 0.001), right vs left colon carcinomas (85% vs 72%, P < 0.001), individual surgeon (P = 0.018), and length of specimen at different cutoffs of at least 30, 25, and 20 cm (P < 0.001). Increasing age was associated with fewer examined lymph nodes (Spearman correlation = -0.22, P < 0.001). Fewer than 12 nodes and T4N0 staging independently affected overall survival (P = 0.003 and P = 0.022, respectively), disease-free survival (P = 0.010 and P = 0.09, respectively), disease-specific mortality (P = 0.009 and P < 0.001, respectively), and overall recurrence (P = 0.13 and P = 0.023, respectively). A minimal number of more than 12 examined nodes had no significant effect on cancer outcomes.
Conclusions: A number of factors influenced lymph node harvest in stage II colon cancer. However, lymph node assessment of at least 12 nodes was the only modifiable factor optimizing cancer outcomes.