4819 - Radiation-induced lung injury and misdiagnosis rate after SBRT

Background

Previously, studies showed the distribution of radiation-induced lung injury (RIL) pattern after stereotactic body radiotherapy (SBRT) of non-small cell lung cancer (NSCLC). However, few analysis data were from China.

Methods

106 lung cancer patients who were treated with SBRT were included, their computed tomography (CT) scans were reviewed. Late injury pattern was classified by Koening’s, radiation lung fibrosis was classified by CTC 5.0, radiologists’ diagnosis for RIL was analyze. Fisher exact test was used for correlation analysis.

Results

Radiographic late injury within at least 6 months after SBRT was concluded. The majority of late RIL pattern was mass-like, not the modified conventional pattern. 36.8% patients showed acute injury. The median time for the occurrence of late injury was 8 months and 4 months for acute injury. Only per fraction dose and the occurrence of acute injury were correlated with different late injury pattern. No grade 2-5 lung fibrosis was observed. 24.5% RIL cases were misdiagnosed to tumor progression by radiologists. Most misdiagnosis occurred among mass-like pattern. We observed 13 patients with atelectasis which may be due to the irradiation of proximal bronchial tree (PBT).

Conclusions

SBRT for lung cancer patients was safe, the majority of late RIL was mass-like pattern. Higher per fraction dose and the occurrence of acute injury were related with mass-like injury pattern. This injury was difficult to be distinguished from tumor progression, which leaded to misdiagnosis of 24.5% patients receiving SBRT. Moreover, the irradiated dose to PBT may be related to the atelectasis after SBRT.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Shanghai Chest Hospital, Shanghai Jiao Tong University.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.