The radiation therapy in keloids treatment: a comprehensive review of pathomechanism, damage mechanisms and cellular response

Keloid management has always been frustrating and challenging. The combination therapy of surgical excision and radiation therapy was deemed as the last resort for decades. The authors performed a thorough and comprehensive review over the mechanisms on how radiation therapy damages the keloid cells. The keloid cells’ cellular response towards damage induced by irradiation was also studied based on original and current literatures. Mechanisms of damage generated by radiation therapy on keloid cells remained partially understood. However, direct damage was identified playing dominant role, in contrast to damage involved cancer cell apoptosis. Moreover, the p53 pathway and some inflammatory factors like interleukin-6 were believed to function in cellular response to irradiation. However, the transforming growth factor beta, which was the major dysregulated pathway involved in pathogenesis of keloid formation showed no apparent correlation with cellular response to irradiation damage. These pathways could partially explain radiation resistance in some refractory keloid lesions. The scientific basis and experimental proof in this field was still inadequate, which drove us to find more evidence to identify the key regulator response to damage engendered by radiation therapy. Further pathway identification may benefit the drug development to prevent keloid recurrence. ABSTRACT