Skin CanceR Brachytherapy vs External beam radiation therapy (SCRiBE) meta-analysis

Background and purpose: To compare cosmesis and local recurrence (LR) of definitive external beam radiation therapy (EBRT) vs brachytherapy (BT) for indolent basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) of the skin. Materials and methods: Studies including patients with T1-2 N0 SCCs/BCCs treated with definitive EBRT/BT and ≥10 months follow-up were analyzed. The primary endpoint was post-treatment cosmesis, categorized as “good,” “fair,” or “poor.” The secondary endpoint was LR. Mixed effects regression models were used to estimate weighted linear relationships between biologically equivalent doses with α/β = 3 (BED₃) and cosmetic outcomes. Results: A total of 9965 patients received EBRT and 553 received BT across 24 studies. Mean age was 73 years, median follow-up was 36 months, and median dose was 45 Gy/10 fractions at 4.4 Gy/fraction. At BED₃ of 100 Gy, “good” cosmesis was more frequently observed in patients receiving BT, 95% (95% CI: 88–100%) vs 79% (95% CI: 60–82%), p < 0.05. Similar results were found for “good” cosmesis at BED₃ >100 Gy. No difference in “poor” cosmesis was noted at any BED₃. LR was <7% for both at one year. Conclusion: BT has favorable cosmesis over EBRT for skin SCCs/BCCs at common fractionation regimens. Prospective studies comparing EBRT vs BT are warranted.