Effect of the biologically effective dose of electron beam radiation therapy on recurrence rate after keloid excision: A meta-analysis

Adjuvant electron beam radiation therapy after keloid excision has been proven as highly effective in reducing local recurrence. We performed a meta-analysis of studies on hypofractionated electron beam radiation therapy after keloid excision based on accurate radiation dose information to provide a more precise estimate of the effect of the biologically effective dose (BED) on recurrence rate.A literature search was performed in PubMed, Embase, and the Cochrane Library for the period from 1990 to December 2021. Studies that provided information on the recurrence rate for the exact prescription dose were selected for analysis. The recurrence rate with respect to the BED was evaluated using forest plots and the best-fit lines on scatter plots.From the 28 studies that were included for analysis, a total of 37 radiation dose datasets were extracted and 3128 excised keloids were identified. The recurrence rate for all sites and for the ear was 0.16 (95% confidence interval, 0.12-0.21; P < 0.01) and 0.11 (95% confidence interval, 0.06-0.20; P < 0.01), respectively. The estimated recurrence rate for all sites and the ear was calculated as "-1.992 + 1018.226/BED2" or "2.982 + 330.51/BED10" and "-16.8 + 1597.84/BED2" or "-14.65 + 656.58/BED10," respectively.Postoperative radiation therapy with higher BED resulted in lower recurrence rates. As expected, ear keloids had lower estimated recurrence rates than all keloids at all sites. We derived a model for estimating the recurrence rate using the dose fractionation scheme.