Dynamic changes in T-cell subsets and C-reactive protein after radiation therapy in lung cancer patients and correlation with symptomatic radiation pneumonitis treated with steroid therapy

OBJECTIVES: To investigate relationships among serum T-cell subsets, CRP, levels and radiation pneumonitis (RP) in lung cancer patients receiving radiotherapy. METHODS: A case–control study with frequency matching was carried out. The case group comprised 36 lung cancer patients who had developed grade ≥2 RP after thoracic radiotherapy. The control group was 36 patients with lung cancer without RP. Patients in the case group received steroid therapy for 1 month after diagnosis of RP and were followed up for 3 months. T-cell subsets, CRP, and pulmonary function were detected at three time points (onset of RP and 1 and 3 months after diagnosis). Data for the control group were collected 3 months after radiotherapy. Treatment effectiveness was evaluated at 1 and 3 months after diagnosis of RP. RESULTS: Of the 36 patients in the case group, three with grade5 RP died from respiratory failure. The other 33 cases had all improved with steroid therapy at 3 months after RP diagnosis. In these 33, CD3(+)T-cell quantity, CD4(+)T-cell quantity, and of CD4(+):CD8(+) ratio in T-cell subsets decreased significantly and CRP increased (P<0.05) at the onset of RP compared with the control group. After steroid therapy, CD4(+)T-cell quantity increased significantly compared to before treatment. The same change was seen in CD4(+):CD8(+) ratio, whereas CRP levels decreased obviously, with treatment effectiveness improved. In addition, with the damage level of RP increased, CD4(+) T -cell quantity decreased obviously and CRP levels increased accordingly at the onset of RP (P<0.05). CONCLUSION: T-cell subsets and CRP may become effective immunological biomarkers for predicting damage from RP and evaluating treatment effectivesness of steroid therapy.