Hypofractionated radiation therapy for basal and squamous cell skin cancer: A meta-analysis

Purpose: To characterize the cosmetic outcomes and local recurrence (LR) rates of various hypofractionated radiation therapy (RT) regimens for skin basal and squamous cell cancers (BCCs/SCCs). Methods: A PICOS/PRISMA/MOOSE selection protocol was performed to identify 344 articles published between 1985–2016 evaluating patients with T1–2 N0 SCCs/BCCs treated with definitive RT. Biologically equivalent doses with α/β = 3 (BED₃s) were calculated. The primary endpoint was post-treatment cosmesis. Mixed effects regression models were used to estimate weighted linear relationships between BED₃ and cosmetic outcomes. Results: A total of 21 studies were identified detailing the treatment of 9729 skin BCC/SCC patients, across seven countries, with external beam RT (n = 9255) or brachytherapy (n = 474). Median follow-up was 36 months (range: 12–77). Median dose was 45 Gy/11 fractions (interquartile range: 37.5 Gy/6–55 Gy/18) at 4 Gy/fraction (interquartile range: 2.5–6 Gy); most hypofractionated 18.75 Gy/1. There was a trend to decreased “good” cosmesis with higher total dose: −3.4% “good” cosmesis/10 Gy BED₃, p = 0.01. Similarly, there was a trend to increased “fair” cosmesis with higher dose: +3.8% “fair” cosmesis/10 Gy BED₃ p = 0.006. At a BED₃ of 100 Gy, the expected rate of “good” cosmesis is 79% (95% confidence interval: 70%, 88%). Hypofractionated schedules produced similar cosmesis to conventionally fractionated schedules, at the same BED₃. Fewer than 8% of patients experienced “poor” cosmesis, independent of dose or fractionation regimen. Conclusion: Hypofractionated RT has favorable cosmesis for patients with skin BCCs/SCCs. We recommend clinicians consider these commonly-used regimens, which all have BED₃ of ∼100 Gy: 50 Gy/15 fractions, 36.75 Gy/7 fractions, or 35 Gy/5 fractions, as they result in “good” cosmesis in 80% of patients.