Abstract: Objective  To investigate the expression of Follistatin-like 3(FSTL3) protein in lung adenocarcinoma(LUAD) tissue and its association with clinical pathological indicators and prognosis.Methods  A total of 268 LUAD patients who underwent radical resection of lung cancer were collected,and the expression of FSTL3 protein in LUAD and paired paracancerous normal tissues was detected using immunohistochemistry.The clinical pathological indicators and overall survival(OS) rate were compared among patients with different levels of FSTL3 expression.Cox- regression model was used to analyze the influencing factors of postoperative OS in LUAD patients.Results The high expression rate of FSTL3 protein in LUAD tissue(55.97%) was significantly higher than that in paracancerous tissues(33.21%)(χ2=28.098,P<0.001).The expression level of FSTL3 protein showed significant differences among LUAD patients with different degrees of differentiation,lymph node metastasis,distant metastasis,and TNM stage(all P<0.05).The OS rate of patients with high FSTL3 protein expression was significantly lower than that of patients with low expression(χ2=4.706,P=0.030).Cox- regression analysis indicated that lymph node metastasis,distant metastasis,TNM stages Ⅲ,and high expression of FSTL3 were independent risk factors affecting postoperative OS in LUAD patients(all P<0.05).Conclusion The expression of FSTL3 protein significantly increased in LUAD tissue,and it was associated with tumor differentiation,lymph node metastasis,distant metastasis,and TNM stage.High expression of FSTL3 was an independent risk factor affecting the postoperative prognosis of LUAD patients.FSTL3 protein has the potential to become a biomarker for early diagnosis and prognostic prediction of LUAD.

Key words: Follistatin-like 3, lung adenocarcinoma, clinical pathological indicators, prognosis, influencing factor