Prognostic relevance of tumor‐resident memory T cells in metastatic lymph nodes of esophageal squamous cell carcinoma

Tumor‐resident memory T (TRM) cells in primary tumors are reportedly associated with a favorable prognosis in several malignancies. However, the behaviors and functions of TRM cells in regional lymph nodes (LNs) of esophageal cancer remain poorly understood. The aim of this study was to elucidate the effects of TRM cells in regional LNs of esophageal cancer on clinicopathological findings and prognosis. Specimens of esophageal cancer and primary metastatic LNs (recurrent nerve LNs) were obtained from 84 patients who underwent radical esophagectomy between 2011 and 2017. We performed immunohistochemistry to enumerate and analyze TRM cells, and used flow cytometry to investigate the function of TRM cells. TRM cells were observed in both metastatic LNs and primary tumors. TRM cell‐rich specimens exhibited reduced lymphatic invasion and LN metastasis and prolonged survival compared with TRM cell‐poor specimens. TRM cells in metastatic LNs were more significantly associated with enhanced survival than TRM cells in primary tumors. TRM cells expressed high levels of granzyme B as a cytotoxicity marker. Our results suggested that high TRM cell infiltration in metastatic LNs improves survival even though LN metastasis is commonly associated with poor prognosis. TRM cells possibly contribute to antitumor immunity in regional LNs. CD103‐positive resident memory T cells infiltrating in metastatic lymph nodes of esophageal cancer improved survival even though lymph node metastasis is commonly associated with poor prognosis. CD103‐positive resident memory T cells in regional lymph nodes possibly contribute to antitumor immune response.