Lymphatic spread patterns in young vs. elderly stage III colon cancer patients

Abstract Background: It currently remains unclear whether the anatomical pattern of lymph node (LN) spread differs between young (≤ 45 years, Y) and elderly (≥ 80 years, E) patients with stage III colon cancer (CC). Materials and Methods: Two groups of patients (Y and E) with stage III CC who underwent extensive (D3) lymphadenectomy at Japanese centers were retrospectively analyzed. The primary endpoint was the proportion of positive central LN. The planned sample size was at least 210 (Y) based on an expected value of 9.1% and threshold of 5%, and 230 (E) based on an expected value of 2% and threshold of 5%. Results: Two-hundred and ten Y patients and 348 E patients were identified and compared. The total number of LN harvested and the total number of invaded LN were significantly higher in group Y (median of 31.5 (3-151) vs. 21 (3-116), P < 0.001 and median of 3 (1–21) vs. 2 (1–25), P < 0.001, respectively). The proportion of positive central LN was higher in group Y than the prespecified threshold of 5% (9.52% (95% CI: 6.24–14.2%), p = 0.007); however it was similar to the threshold in group E (4.59% (95% CI:2.84–7.31%), p = 0.351). In multivariate models, central LN invasion was identified as a poor prognostic factor in group Y (HR3.66 (95% CI (1.29–8.87)), but not in group E (HR2.02 (0.95–4.27)). Conclusions: Young stage III colon cancer patients have a higher risk of central LN invasion, suggesting a more aggressive disease biology. The presence of central LN invasion is associated with a worse outcome.