Prognostic biological factors of radiation pneumonitis after stereotactic body radiation therapy combined with pulmonary perfusion imaging.

Radiation pneumonitis (RP) is one of the most common dose-limiting toxicity syndromes in patients with thoracic malignant tumors receiving radiotherapy. The present study aimed to identify biological factors for the prediction of RP. Pulmonary perfusion imaging is capable of reflecting the differential functional activity of various regions of the lung, and in the present study, radiotherapy plans that were established on the basis that pulmonary perfusion images have high biological conformality, which may identify regions vulnerable to RP to spare them from radiation. A total of 46 patients with non-small cell lung cancer (NSCLC), exhibiting high and low levels of apurinic/apyrimidinic endonuclease-1 (Ape-1), intercellular adhesion molecule (ICAM)-1 and interleukin (IL)-17A prior to treatment, with SBRT with respective cut-off values of 4.2, 3.0 and 5.1 µg/l were stratified into groups A and B. Patients received radiation doses within the margin of the planning target volume. Stereotactic body radiation therapy (SBRT) was used for the treatment of NSCLC and single-photon emission computed tomography pulmonary perfusion imaging was used to assess all patients for the presence of RP. Furthermore, the serum levels of Ape-1, ICAM-1 and IL-17A were examined by ELISA. Prior to SBRT, perfusion images indicated that no RP was present in any of the patients, and 23 patients had high levels of Ape-1, ICAM-1 and IL-17A. After SBRT, 22 out of 23 patients in group A (95.65%) presented with RP and 1 patient (4.35%) had no RP. In group B, 6 out of 23 patients (26.09%) had RP and 17 patients (73.91%) had no RP after SBRT. The difference between the two groups in the incidence of RP was significant (P=1.66×10-12 <0.05). In conclusion, high levels of Ape-1, ICAM-1 and IL-17A are associated with an increased risk of RP. A further analysis should be performed in the future to verify whether these factors have significant prognostic value.