Clinical significance of peritumoral mast cells in esophageal squamous cell carcinoma with neoadjuvant chemoradiotherapy

Neoadjuvant chemoradiotherapy (CRT) followed by surgery is the standard approach for locally advanced esophageal cancer. Recently, the microenvironment (including the host immune response) after conventional chemo- and/or radiotherapy has been highlighted. The aim of this preliminary study was to evaluate peritumoral mast cells (MCs) in esophageal squamous cell carcinoma (ESCC) after neoadjuvant CRT. We obtained a total of twenty specimens from patients with ESCC who underwent neoadjuvant CRT (30-40 Gy; 5-fluorouracil plus cisplatin) followed by surgery. We evaluated the expression of tryptase by MCs, Foxp3 by regulatory T cells, CD8 by cytotoxic T cells, and microvessel density (MVD) using immunohistochemistry. We investigated the correlation between the sizes of these marker-positive cell populations surrounding residual tumor nests, MVD and CRP, and clinical outcome. Patients with a low number of peritumoral MCs more frequently had lymphatic invasion (P = 0.0191). There was no significant correlation among the sizes of the marker-positive cell populations. We observed a significant negative correlation between the number of MCs and preoperative CRP levels (P = 0.009). Low numbers of peritumoral MCs, high MVD, and a preoperative C-reactive protein of > 0.5 mg/dL were significantly associated with poor overall survival (MCs: P = 0.0239; MVD: P = 0.0317; CRP: P = 0.0395). Our results suggest that peritumoral MCs may be associated with prognosis in patients with ESCC after neoadjuvant CRT.