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Most so-called "beneficial bacteria" in gut microbiota are Gram-positive, and TLR6 recognizes the peptidoglycan (PGN) present in their cell walls. We hypothesized that a high TLR6 expression status predicts a more favorable prognosis after esophagectomy. We used an ESCC tissue microarray (TMA) to examine TLR6 expression status in ESCC patients and to determine whether TLR6 expression status correlates with prognosis after curative esophagectomy. We also examined whether PGN influences the cell proliferation activity of ESCC lines. Clinical ESCC samples from 177 patients tested for the expression of TLR6 were categorized as 3+ (n = 17), 2+ (n = 48), 1+ (n = 68), or 0 (n = 44). High TLR6 expression (3+ and 2+) correlated with significantly more favorable 5-year overall survival (OS) and disease-specific survival (DSS) after esophagectomy than a lower TLR6 expression (1+ and 0). Univariate and multivariate analyses showed that TLR6 expression status is an independent prognostic factor that affects 5-year OS. PGN significantly inhibited the cell proliferation activity of ESCC lines. This is the first study to show that high TLR6 expression status predicts a more favorable prognosis in locally advanced thoracic ESCC patients after curative esophagectomy. PGN released from "beneficial bacteria" seems to have potential to inhibit the cell proliferation activity of ESCC.

Background: Patients with 18 F-fluorodeoxyglucose-positron emission tomography (FDG-PET)-positive lymph nodes before treatment have a poor prognosis after esophagectomy. This study investigated whether FDG uptake into lymph nodes on FDG-PET (PET-N) during the pre- or posttreatment stage is more predictive of survival for thoracic esophageal squamous cell carcinoma (TESCC) patients who received neoadjuvant chemoradiotherapy (NACRT) followed by esophagectomy., Methods: Of 129 TESCC patients with clinical lymphatic metastasis who underwent curative-intent esophagectomy after NACRT between 2010 and 2018, 97 who received PET before and after NACRT were enrolled in the study. The study defined lymph nodes with a maximum standardized uptake value (SUV max ) greater than 2.5 on FDG-PET before NACRT as cPET-N(+) and after NACRT as CRT-cPET-N(+). Both the cPET-N(+) and CRT-cPET-N(-) patients were defined as PET-N responders. Survival was analyzed using the Kaplan-Meier method and Cox proportional hazard models., Results: No significant difference in survival was detected between the cPET-N(+) and cPET-N(-) patients. However, the CRT-cPET-N(-) patients had significantly better 5-year overall survival (OS) and disease-specific survival (DSS) than the CRT-cPET-N (+) patients. The PET-N responders had significantly better 5-year OS and DSS than the PET-N non-responders, and PET-N response was an independent prognostic factor for 5-year DSS., Conclusion: The PET-N response is a highly predictive prognostic marker for TESCC patients who undergo NACRT followed by esophagectomy. The PET-N response may help clinicians to establish a strategy for perioperative treatments that improves survival for patients with lymph node metastasis in TESCC., (© 2021. Society of Surgical Oncology.)