For the pathogenesis of the radiation injury theory, fibrosis is a result of abnormally healed inflammatory changes during the pneumonitis stage.[5] Our aim was to investigate the prognostic role of CCL18 for radiation inflammation i.e. pneumonitis which leads to permanent injury i.e. fibrotic remodeling of the lung, hypothesizing that an increase of the CCL18 concentrations could be predictive for lung injury after radiotherapy. This evidence concerns the gene CCL18 and pneumonitis.