Occult neoplastic cells in the lymph node sinuses and recurrence/metastasis of stage II/Dukes' B colorectal cancer

Lymph nodes from patients with colorectal cancer were immunohistochemically stained for cytokeratin in order to investigate the relationship between the presence of occult neoplastic cells (ONCs) and recurrence/metastasis. A total of 78 patients with stage II/Dukes' B colorectal cancer were divided into two groups. The first group consisted of 18 patients who had developed recurrence/metastasis (recurrence group) and the other one of 60 patients who had survived without recurrence (non-recurrence group). The presence of ONCs was compared between the two groups with respect to i) single cells (≥3 floating ONCs), ii) clusters of cells (≥1 floating aggregates of 2-20 ONCs), and iii) single cells + clusters. When single cells were detected, the sensitivity for recurrence was 55.6% (10/18), the positive predictive value (PPV) was 30.3% (10/33), the specificity was 61.7% (37/60, p=0.195), and the negative predictive value (NPV) was 82.2%(37/45). For the clusters, the sensitivity was 55.6% (10/18), PPV was 37% (10/27), specificity was 71.7% (43/60, p=0.033), and NPV was 84.3% (43/51). With single cells + clusters, the values were 55.6% (10/18), 43.5% (10/23), 78.3% (47/60, p=0.006), and 85.5% (47/55), respectively. These results suggest that the detection of single cells + clusters has a high specificity and NPV, and indicates a low risk of recurrence/metastasis in patients with stage II colorectal cancer.