Use of Topical Superoxide Dismutase in the Management of Radiation-induced Fibrosis: A Neglected Opportunity?

Fibrosis of the dermis and keratosis of the epidermis are frequent late complications of irradiation, this being accidental or a consequence of radiotherapy. Fibrosis is a complex tissue response whose predominasnt characteristics are massive deposition of extracellular matrix and excessive fibroblast proliferation. A perpetual cascade of cytokines has been identified post-irradiation in irradiated tissues, and the occurrence of fibrosis is under strong control of the same. Among these increased cytokines, it was clearly demonstrated that TGF-beta1 is a key player. The biological implications of the free radicals generated are now considered important in causing the oxidative damage and hence fibrosis. In such conditions, topical applications of antioxidants could result favorable in the management of radiation-induced fibrosis. Superoxide dismutase (SOD), one of the most potent antioxidants known to date, can be an effective active ingredient at this stage. In the past, various clinical trials have demonstrated the beneficial effects of topical superoxide dismutase on radiation-induced fibrosis. Since then, it seems that the interest for this topical antioxidant has vanished, whilst it still remains an efficient and safe alternative for treating damages caused by irradiation.Background: Radiation-induced fibrosis (RIF) is a complication of radiotherapy that may develop in normal tissue several months to several years following high-dose irradiation. RIF is characterized by non-specific changes in the vascular connective tissue involving excessive extracellular matrix deposition, fibroblast proliferation and the presence of inflammatory infiltrate [45].Conclusion: Recent progress in understanding the pathophysiology of RIF in conjunction with topical antioxidant therapy suggests a new treatment option for what has long been considered an irreversible process.