We investigated the clinicopathological significance of dendritic cell infiltration (DCsI) in esophageal squamous cell carcinoma and in regional lymph nodes of 88 patients. The expression of mutated p53 protein and the degree of positive cancer cells of proliferating cell nuclear antigen (PCNA labeling index) in tumors were analyzed as biological markers. These factors were compared with the degree of DCsI in tumors and in lymph nodes. The number of dendritic cells (DCs) were counted and scored as per mm2 in each case. The degree of DCsI of tumors with expression of p53 (19/mm2, n=50) was significantly lower than that of DCsI in 38 tumors without expression of p53 (27/mm2, P=0.0411). However, no significant correlation was detected between the PCNA labeling index and the degree of DCsI in 88 primary tumors (P=0.1273). The degree of DCsI in 53 metastatic lymph nodes (30/mm2) was significantly lower than that of DCsI in 264 cancer-free regional lymph nodes (48/mm2, P=0. 02). Although the degree of DCsI in tumors was not an independent prognostic factor for the 78 surviving patients (P=0.2647), the 3-year survival rate of patients in stage III and IV who underwent curative operation and who had tumors with high DCsI (>9/mm2, n=16, 72%) was significantly higher than that of the 24 patients who had tumors with low DCsI (< or = 9/mm2, 21%, P=0.008). These findings indicate that DCs infiltrated in and around the esophageal cancer may play a defensive role of the hosts against the tumors. This immune defense of the hosts might be an important prognostic factor for patients with advanced esophageal cancer. However, cancer cells which express a mutated p53 protein might regulate the function or activity of DCs.

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