Treatment of keloids with a single dose of low-energy superficial X-ray radiation to prevent recurrence after surgical excision: An in vitro and in vivo study

Background: Although keloids have been empirically treated with steroids and radiation, evidence-based radiation parameters for keloid therapy are lacking. Objective: To determine evidence-based radiation parameters for blocking keloid fibroblast proliferation in vitro and apply them to patients. Methods: The effects of various radiation parameters and steroids on cell proliferation, cell death, and collagen production in keloid explants and fibroblasts were evaluated with standard assays. Effective radiation parameters were then tested on patients. Results: No differences were observed between the effects of 50 and 320 kV radiation or between single and fractionated radiation doses on keloid fibroblasts. A 3 Gy, 50 kV dose inhibited keloid fibroblast proliferation in culture, whereas 9 Gy completely blocked their outgrowth from explants by inducing multiple cell death pathways and reducing collagen levels. Thirteen of 14 keloids treated with a single 8 Gy, 50 kV dose of radiation did not recur, although 4 patients with 6 keloids were lost to follow-up. Limitations: Seventy-five percent of patients received steroids for pruritus, whereas approximately 25% of patients were lost to follow-up. Conclusions: A single 8 Gy dose of superficial 50 kV radiation delivered an average of 34 days after keloid excision maybe sufficient to minimize recurrence, including in individuals resistant to steroids. Higher radiation energies, doses, or fractions may be unnecessary for keloid therapy.