Abstract 391P
Background
Radiation therapy (RT) is a widely used treatment modality for various malignancies, particularly in thoracic cancers such as non-small cell lung cancer. However, one of the significant complications associated with RT is radiation-induced lung injury (RILI). Our study aimed to evaluate the dose-dependent efficacy of melatonin (MLT) in mitigating radiation-induced lung injury in a rat model, focusing on its potential protective effects against pneumonitis and pulmonary fibrosis following RT.
Methods
A total of 45 male Sprague Dawley rats were divided into five. The control group was injected with 1 ml saline solution before sham irradiation. The second group had 1 ml saline injection and 12 Gy thoracic RT. For the remaining groups, MLT was administered at a dose of 100 mg/kg, 50 mg/kg, and 5 mg/kg. or saline prior to RT. Hematoxylin and eosin stained lung tissues were evaluated using the semi-quantitative scoring method developed by Downing et al., which is based on the determination of the alveolar septum area.
Results
Control groups mean of alveolar septal area was 38 + 11,07. Numerically RT only group displayed deteriorated alveolar space and alveolar septa thickening with a mean of 42,3 + 6,60 yet the difference among RT and control group was not statistically significant. The MLT 100 mg/kg group displayed the most alveolar space decrease and an extended increase in alveolar septal thickening with a mean of 49,0 + 12,37. MLT 50 mg/kg and 5 mg/kg groups displayed normal alveoli and less degraded alveolar septa with an alveolar septum area of 35,0 + 9,08 and 31,1 + 5,73, respectively. When compared to the 100 mg/kg MLT group, the alveolar septal difference between 50 and 5 mg/kg MLT groups were statistically significant (Group 3 vs 4 p=0,034; Group 3 vs 5 p=0,003). This significance implies that 100 mg/kg MLT dose induced more pro-fibrotic changes in lung tissues thus diminishing the alveolar space due to potential prooxidant effects of high dose MLT.
Conclusions
These findings highlight the importance of MLT dosage in managing RILI, with lower doses potentially offering protective effects against lung injury.
Legal entity responsible for the study
E. Demir
Funding
Has not received any funding
Disclosure
All authors have declared no conflicts of interest.