ABSTRACT
External beam radiotherapy is a major treatment in the management of cancer .However radia-tion induced pulmonary fibrosis is common .It not only leads to quality -of-life issues in survivors and compro-mise treatment ,but also may even be lethal in outcome .Transforming growth factor β( TGF-β) seems to be a key mediator of fibrosis .TGF-βpromotes the differentiation of fibroblasts into myofibroblasts while the differentiation and activation of fibroblasts and myofibroblastsmay produce the components of scar tissue, which is one of the key pathogenic processes in lung fibrosis .Peroxisome proliferator activated receptors ( PPARs ) are ligand activated transcription factors that belong to the nuclear hormone receptor superfamily .PPARγis also a key regulator of fi-broblast differentiation .Many studies have shown that both natural ligand and synthetic ligand of PPARγcan sup-press fibrosis by interfering with TGF -βsignaling and some other approaches .The antifibrotic effects of PPARγhave been reported to be involved in both PPARγdependent and PPARγindependent mechanisms .PPARγago-nists may have potential for the therapy of radiation induced pulmonary fibrosis .