CT features of radiation-induced lung injuries can show the prognosis after stereotactic ablative radiotherapy in early-stage non-small cell lung cancer

Objective To investigate the correlation between peritumoral radiation-induced lung injuries and prognosis of early non-small cell lung cancer after stereotactic ablative radiotherapy (SABR). Methods Clinical data and follow-up imaging data of patients with early NSCLC who received SABR treatment in Department of Thoracic Radiotherapy of Zhejiang Cancer Hospital from January 2012 to December 2018 were retrospectively collected, and the Progression Free Survival (PFS) was calculated. CT features of peritumoral radiation-induced lung injuries were observed by 3 radiologists with more than 10–15 years of experience. CT features of peritumoral radiation-induced lung injuries were divided into 3 types. Type 1 was diffuse consolidation around the tumor with the tumor boundary covered. Type 2 is the diffuse ground glass shadow around the tumor, which is distributed in the range of more than 180 degrees around the tumor. Type 3 is the patchy ground glass shadow surrounding the tumor within a range of less than 180 degrees. Log-rank test was used to analyze the correlation between CT features of radiation-induced lung injuries and PFS rate of NSCLC after SABR. Independent influencing factors of PFS rate were analyzed by COX multivariate regression. Results 5-year PFS rate corresponding to CT features of peritumoral radiation-induced lung injuries 3–5 months after SABR in early lung cancer were type 1:68.1%; Type 2:73.1%; Type 3:35.3%; there was a statistical difference between the CT features of three types of peritumoral radiation-induced lung injuries (p = 0.006). The 5-year PFS rate corresponding to the CT features of peritumoral radiation-induced lung injuries 6–8 months after SABR were type 1:69.5%; Type 2:50.9%; Type 3:36.1%; there was statistical difference between the CT features of three types of peritumoral radiation-induced lung injuries (p = 0.025). COX multivariate regression analysis showed that the CT features of peritumoral radiation-induced lung injuries were independent factors influencing PFS rate (at 6–8 months follow-up after radiotherapy (p = 0.041). Conclusions CT features of peritumoral radiation-induced lung injuries can predict the recurrence risk of early non-small cell lung cancer after SABR, and the type of CT features at 6–8 months after SABR was an independent predictor of recurrence risk.