Solitary lymph node metastasis is a distinct subset of colon cancer associated with good survival: a retrospective study of surveillance, epidemiology, and end-results population-based data

BACKGROUND: Colon cancer with lymph node metastases has been considered as advanced stage and to have poor survival. We postulated that patients with solitary lymph node metastasis are a distinct subset with better colon cancer-specific survival than those with multiple lymph node metastases. METHODS: In this retrospective study, we searched Surveillance, Epidemiology, and End-Results (SEER) population-based data and identified 86,674 patients who had been diagnosed with colon cancer without distant metastases and with less than three metastatic nodes between 1991 and 2005. We divided lymph node status into three subgroups: pN0, pN1a, and pN1b and obtained 5-year colon cancer-specific survival for each pT stage. We used Kaplan–Meier and multivariate Cox regression models to assess correlations between risk factors and survival outcomes. RESULTS: Analysis of SEER data confirmed that patients with solitary lymph node metastases had better 5-year cancer-specific survival than pN1b according to both univariate and multivariate analysis. This finding was confirmed by further analyses in five pT subgroups. Cancer-specific survival of patients with pT1-2N1a was comparable to that of those with pIIA but higher than those with pIIB. In addition, survival of patients with pT3-4aN1a was better than those with pIIC. CONCLUSION: Colon cancer patients with solitary lymph node metastasis are a distinct subset with a favorable prognosis; full consideration should be given to this in clinical practice.