Post-Excision Soft X-Ray Radiotherapy for Keloids: Experience in a Tertiary Referral Center

Keloid is an abnormal proliferation of scar tissue that grows beyond the original margins of the injury. Even after complete resection, recurrences are common and pose a poorly understood challenge in dermatology. There is lack of large prospective clinical trials; thus, treatment recommendations are based on retrospective analyses and small cohort studies. Superficial radiotherapy is recommended in recurrent keloids; however, the successful treatment rates vary greatly. The aim of this study was to evaluate the keloid recurrence rate after post-excision soft X-ray radiotherapy and the associated factors.

We reviewed retrospective data of all patients, treated with adjuvant post-excision soft X-ray radiotherapy with 12 Gy in 6 sessions at the tertiary referral center, Department of Dermatology, University Hospital Zurich, Switzerland, between 2005 and 2018. We analyzed individual keloids as separate cases. Successful treatment was defined as no sign of recurrence within 2 years.

Of the 200 identified patients, 90 met the inclusion criteria and were included in the final analysis. In 90 patients, 104 cases of treated keloids were analyzed. Keloids were mainly located on the trunk (49%) and were mostly caused by previous surgery (52.2%). 50% of the keloids did not relapse within 2 years after therapy. A significant factor leading to recurrence was the presence of previous therapy, with prior topical therapies, such as steroid injections or 5-fluorouracil, leading to most relapses. 69.2% of keloid cases who relapsed were pretreated. Soft X-ray radiotherapy was well tolerated, with posttreatment hyperpigmentation noted in 34% of patients, particularly in patients with non-Caucasian origin (61.3%).

Treatment of refractory keloids is difficult. Post-excision radiotherapy is an established adjuvant treatment option; nevertheless, recurrence rates are high, especially in pretreated keloids. Prospective studies determining the exact dosage and fraction of post-excisional radiotherapy are needed to determine the optimal radiation parameters.