Number of Lymph Nodes Examined as a Prognosis Factor in Patients With Stage II or III Colon Cancer.

Background: Lymph node (LN) examination is important for staging colorectal cancer. Examining < 12 LN has been associated with a poor prognosis. However, surgical and pathological advances have led to increase examined LN, necessitating the reassessment of the best cutoff for prognosis.

Methods: We reviewed patients with stage II-III colon cancer from the Yonsei Cancer Center Registry (YCC) database and the Netherlands Cancer Registry (NCR). The optimal LN cutoff was determined by comparison with hazard ratio (HR) in 12 LN. We compared higher vs. lower LN cutoff effects on a 6-year overall survival (OS).

Results: From 2005 to 2015, the proportion with < 12 LN decreased significantly (P < .001). There was no significant association between 6-year OS and LN yield in all stages II-III patients (HR = 1.21, P = .116), stage II (HR = 1.39, P = .068), and stage III (HR = 1.18, P = .297) colon cancer based on the standard 12 LN examined, whereas the 20 LN cutoff examined was associated with a significant increase in 6-year OS in all patients (HR = 1.51, P < .001). Multivariate regression revealed a significant decrease in 6-year OS in stage II (HR = 1.39, P = .026) and stage III (HR = 1.47, P < .001) with < 20 LN yield. In the NCR, < 20 LN was associated with poorer 6-year OS in stage II-III patients (HR = 1.25, P < .001), stage II (HR = 1.43, P < .001), and stage III (HR = 1.13, P = .007).

Conclusions: Over the past decade, inadequate LN examinations have significantly decreased. Compared to < 12 LN, < 20 LN examined is more associated with a worse prognosis in patients who underwent surgery.