In colon cancer, patients with many retrieved lymph nodes (LNs) have good outcomes. We previously reported that the longest diameter of retrieved LNs correlates with the number of retrieved LNs and is thus a predictor of outcomes (Int J Colorectal Dis 2015). LNs can be divided into three main regions: the cortex, the paracortex, and the medulla, and consist mainly of T cells, B cells, natural killer (NK) cells, and histiocytes. We studied the relations of the T-cell region, B-cell region, and the number of NK cells to the number of retrieved LNs, LN size, and outcomes.
The study group comprised 320 patients with stage II colon cancer who underwent curative resection from 1991 through 2003. All operations were performed by the same team and LN dissection was performed to the origin of the feeding artery. LN with maximum long axis diameter (maximum LN) was selected in each patient and immunostained with CD3 as a T-cell marker, CD20 as a B-cell marker, and CD56 as an NK-cell marker. CD3-positive area ratio and CD20-positive area ratio were calculated using the image analyzer. The number of CD56-positive cells were counted at 6 sites and the mean number per 0.093 mm2 was calculated.
The number of retrieved LNs was 14.8 ± 10.1 (mean ± SD). The mean CD3-positive area ratio was 0.39 ± 0.08. The mean CD20-positive area ratio was 0.42 ± 0.10. The mean number of CD56-positive cells was 10.7 ± 9.6. Multivariate analysis showed that the diameter of the maximum LN significantly correlated with the following variables (in the order of the strongest to weakest): number of CD56-positive cells, age, tumor location, CD20-positive area ratio and sex. The number of retrieved LNs positively correlated with tumor location, age, number of CD56-positive cells, and CD20-positive area ratio. The median follow-up was 118 months. Multivariate analysis showed that age, tumor location, T stage, CD20-positive area ratio, and the number of CD56-positive cells were independent prognostic factors of survival.
B cell area ratio and the number of NK cells in maximum LNs were independent prognostic factors related to LN size, the number of retrieved LNs and survival in Stage II colon cancer.
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All authors have declared no conflicts of interest.