The outcome and the adverse effect of postoperative radiotherapy for keloids: A prospective study with a total dose of 20 Gy

Abstract

Until 1994, keloids had been treated with resection and postoperative radiotherapy with a various radiation dose in our institution. The most frequent dose used was 16 Gy and 24 Gy. In a retrospective evaluation, the relapse rate and the incidence of hyperpigmentation and/or telangiectasis was 49% and 15% at 16 Gy, and 8% and 29% at 24 Gy, respectively, suggesting a dose-response relationship both in keloid control and morbidity. Since 1995, the total dose was fixed to 20 Gy in 5 fractions, in expectation of preserving the cosmetic outcome without compromising on the control rate. We report in the present study the outcome and the adverse effects in patients with postoperative keloids treated with 20 Gy. From January 1995 to May 2003, 235 keloids in 181 patients (62 male and 119 female, median age 33 years old) received postoperative radiotherapy with a total dose of 20 Gy in 5 fractions over 9 to 14 days. Soft X-rays (55 or 100 kVp) or electron beams (5 or 7 MeV) were used. The 90% isodose target area included the entire postoperative scar and any suture/puncture hole with a margin of 3–5 mm around the lesion. Non-target area was shielded by individually cut-out 1–2 mm lead sheet. The size and height of keloid, cosmetic status, symptoms, and adverse effects were prospectively evaluated every several months after radiotherapy. The median follow-up period was 21.4 months (range 6–81 months). All patients completed the scheduled treatment. 27 out of 235 keloid scars (11%) relapsed. A univariate and a multivariate analysis with various prognostic factors showed that the relapse rate was significantly correlated with the site of keloids. The relapse rate was 15% for the keloid scars under high stretch tension (e.g. anterior chest wall, shoulder, and suprapubis), while 0% for those without high tension (e.g. face, neck, earlobes, hip, and lower limbs). Cosmetic status was judged to be excellent in 48 lesions (20%), good in 152 lesions (65%), and fair in 24 lesions (10%). Among 191 lesions, which caused itching and/or pain before treatment, symptomatic relief was achieved in 177 lesions (93%). No severe (grade 3 or above) treatment-related toxicity was observed. The incidence of hyperpigmentation and/or telangiectasis was 10%. Comparing the present results in the patients treated with 20 Gy to the previous results in the patients treated with 16 and 24 Gy in our institute, the keloid relapse rate after 20 Gy was significantly lower than that after 16 Gy and comparable to that after 24 Gy, while the incidence of adverse effects after 20 Gy was comparable to that after 16 Gy and lower than that after 24 Gy. We concluded, therefore, 20 Gy is the optimal total dose for the postoperative radiotherapy of keloids. The extremely low relapse rate for the keloids on the loose skin suggested that the use of a lower total dose may be warranted for these lesions