Changes in serum transforming growth factor-beta concentration as a predictive factor for radiation-induced lung injury onset in radiotherapy-treated patients with locally advanced lung cancer.

Background: Radiation-induced lung injury (RILI) occurs after chest radiation therapy, which ranges from acute radiation pneumonia to subsequent radiation pulmonary fibrosis. However, they are difficult to predict. The study aimed to examine the predictive utility of serum levels of transforming growth factor-beta (TGF-β) for radiation-induced lung injury. Methods: This single-center prospective observational study enrolled 21 patients with locally advanced lung cancer who underwent chest radiation therapy. We measured the serum levels of TGF-β, Krebs von Denlungen-6, and granulocyte colony-stimulating factor (GCSF) eight times immediately before irradiation. Results: Seven, four, eight, and one patient had Grade 0, 1, 2, and 3 radiation-induced lung injury, respectively. Compared with the Grade 0 and 1 RILI groups (RP- group), the Grade 2 and 3 RILI groups (RP+ group) had a significantly higher relative ratio of TGF-β values from immediately before irradiation to the time of 30-48 Gy irradiation (P=0.011). The cut-off value of the TGF-β relative ratio of the RP+ group measured from the receiver operating characteristic curve was 1.31; moreover, the sensitivity, specificity, and positive predictive value were 75%, 100%, and 75%, respectively. There was no significant between-group difference in the levels of the other cytokines. Conclusions: For patients undergoing radiation therapy for locally advanced lung cancer, the ratio of TGF-β levels before and after 30-48 Gy irradiation may predict the onset of RILI. Our findings may facilitate the identification of predictors of the onset of radiation-induced lung injury.