494 Background: In colon cancer, retrieval of less than 12 lymph nodes is a risk factor for recurrence. We previously reported that the long-axis diameter of the largest LNs (maximum LNs) is associated with a higher number of retrieved LNs and better outcomes in stage II disease (Int J Colorectal Dis 2015). Furthermore, the number of natural killer cells in the maximum LNs is associated with the number of retrieved LNs and lymph node size, and is an independent prognostic factor (Oncology 2018). We examined whether the long-axis diameter of maximum LNs with and without metastasis is a prognostic factor in stage III colon cancer. Methods: The study group comprised 190 patients with stage III colon cancer from 2005 to 2014. For each patient, one negative LN and one positive LN with the greatest long-axis diameter were selected, and the diameter was measured on H-E stained specimens. The endpoint of survival analysis was relapse free survival (RFS). The cut-off value (COV) was determined by using receiver operating characteristic curves. Results: The mean long-axis diameter of maximum negative and positive LNs were 8.5 ± 3.7 and 9.9 ± 4.9 mm, respectively. Factors related to the number of retrieved LNs were the tumor size (less than 4.3 cm, 13.5 ± 6.4; 4.3 cm or more, 16.6 ± 7.3; p = 0.004) and the long axis diameter of maximum negative LNs (< 8.1 mm, 13.4 ± 6.9; ≥ 8.1 mm, 17.6 ± 6.6; p < 0.001). Maximum negative LNs with a diameter of ≥ 8.1 mm was associated with significantly better RFS than maximum negative LNs with a diameter of < 8.1 mm (p = 0.020). The diameter of maximum positive LNs was not a prognostic factor. On multivariate analysis, the tumor size (≥ 4.3 cm/< 4.3 cm, HR 3.02; p < 0.001), venous invasion (absent/present, HR 0.41; p = 0.017), the number of LNs (≥ 12/< 12, HR 0.56; p = 0.043), and the diameter of maximum negative LNs (≥ 8.1 mm/< 8.1 mm, HR 0.45; p = 0.008) were independent prognostic factors. Conclusions: In stage III colon cancer, the long-axis diameter of negative maximum LNs was a prognostic factor. Enlarged negative LNs are caused by hyperplasia of cell components in LNs. The size of negative maximum LNs might reflect the tumor immunity of the host.
Superior prognosis stratification for stage III colon cancer using log odds of positive lymph nodes (LODDS) compared to TNM stage classification: the Japanese study group for postoperative follow-up of colorectal cancer
