Abstract
Patients with keloids experience sharp pains and itchiness. Radiotherapy after keloid excision is effective for preventing keloid recurrence; however, there is no consensus on the ideal dosage. We used time-dose fractionation (TDF) and biologically effective dose (BED) to compare different time doses and standardize the radioactivity dosage. Informed consent was obtained from all patients. From 1994 to 2005, we irradiated high tension sites with 2 Gy, using a 4-MeV electron beam for 5 weeks, a total of 10 times (total dose, 20 Gy; BED, 24 Gy; TDF, 32.2). From 1995, we irradiated these sites with 3 Gy, using a 4-MeV electron beam for 5 weeks, a total of 10 times (total dose, 15-24 Gy and average dose, 20.05 Gy; total BED, 19.5-31.2 Gy and average BED, 26.2 Gy; total TDF, 30.01-48.1 and average TDF, 40.20). For low tension sites, we changed the dosage from 2 Gy for 5 weeks with gross radioactivity, 16 Gy; BED, 19.2 Gy; and TDF, 25.8 for a total of 8 times to 3 Gy for 4 weeks with gross radioactivity, 12 Gy; BED, 15.6 Gy; and TDF, 24.1. We compared the recurrence rates between 27 sites receiving 2 Gy and 25 sites receiving 3 Gy of irradiation. The rates did not differ significantly at both the high and low tension sites. Therefore, 12 Gy of radiation is sufficient to prevent recurrence. However, TDF differed between the 2-Gy and 3-Gy groups. The irradiation dosage is important to prevent recurrence/complications. Longer follow-up of the outcome and late toxicity is required.
