Expression of FGL1, Distribution of Tumor-Infiltrating Lymphocytes, and Their Clinical Significance in Esophageal Squamous-Cell Carcinoma

Objective To explore the expression of fibrinogen-like protein 1 (FGL1), the distribution of tumor-infiltrating lymphocytes (TILs), and their relationship with the prognosis of esophageal squamous-cell carcinoma (ESCC) patients.

Methods We analyzed retrospectively the clinical data of 120 ESCC patients. The expression of FGL1 was detected through immunohistochemistry. The distributions of intratumoral TILs (iTILs) and stromal TILs (sTILs) were evaluated under a microscope. Survival analysis was used to evaluate the patient outcomes.

Results The positive rate of FGL1 in ESCC was 18.3% (22/120), and it was connected to the TNM stage, lymph node status, and TILs. A total of 73 cases (60.8%) showed low levels of iTILs (iTILs≤10%), and 47 cases (39.2%) exhibited high iTIL levels (iTILs > 10%). Similarly, 82 cases (68.3%) presented low levels of sTILs (sTILs≤10%), and 38 cases (31.7%) manifested high sTIL levels (sTILs > 10%). The distribution of iTILs was associated with FGL1, tumor differentiation, and TNM stage, whereas the distribution of sTILs was associated with FGL1, tumor location, and TNM stage. The Kaplan–Meier survival analysis showed that tumor diameter, TNM stage, lymph node status, FGL1, and TILs were associated with the prognosis of patients with ESCC (P < 0.05). Multivariate Cox regression revealed that FGL1, TILs and TNM stage were the influencing factors of prognosis.

Conclusion FGL1 expression is associated with the poor prognosis and may be a prognostic biomarker of ESCC. FGL1 combined with TILs can be used as a biomarker to predict ESCC.