Purpose: To investigate the correlation between number of retrieved lymph nodes (rLNs) and prognosis and further ascertain the optimal number of rLNs with a beneficial survival impact in patients with pN0 colon cancer.
Methods: The Surveillance, Epidemiology, and End Results (SEER) database was searched for pN0 colon cancer cases. X-Tile software and Kaplan-Meier survival analysis were applied to determine the optimal number of rLNs based on the minimal probability (P) value and the largest χ2 value. Univariate analyses and Cox proportional hazard regression model were used to investigate the relationship between rLN number and overall survival. Multiple analyses were conducted to assess the prognostic predictive ability of the identified optimal rLN cut-off value under different stratifications. Nomograms were established based on the independent prognostic factors selected by the multivariate analysis to predict 3- and 5-year overall survival rates of pN0 patients.
Results: A total of 6269 pN0 colon cancer patients who underwent surgical therapy were finally included for analysis. Harvest of at least 18 lymph nodes was determined as the optimal rLN number. This cut-off rLN value (< 18 versus ≥ 18) was identified as an independent prognostic factor (P < 0.001) of overall survival via multivariate analysis. Similar findings were obtained in patients with retrieval of at least 12 lymph nodes (18 > rLNs ≥ 12 versus rLNs ≥ 18) stratified into several groups.
Conclusions: The number of rLNs was identified as an independent prognostic factor for pN0 colon cancer. Retrieval of at least 18 lymph nodes was associated with favorable prognosis in patients with pN0 colon cancer, and should, therefore, be regarded as an alternative cut-off value for survival analysis.
Keywords: AJCC/UICC; Colon cancer; Retrieved lymph nodes; SEER; pN0 patients.