Observational pilot study investigating skin metrics in acute radiation dermatitis

Summary: Radiation dermatitis (RD) occurs in ~ 95% of those undergoing radiation therapy (RT), with severe reactions observed in 10-30% of individuals. The pathophysiology of RD is complex and multifactorial, with skin barrier disruption thought to play a central role. This single institution observational pilot investigates the effects of RT on skin metrics to uncover any association of skin changes with acute RD severity. We hypothesize that worse acute RD outcomes are associated with greater skin barrier impairment, high S. aureus (Sa) abundance, and pre-existing skin conditions. Outcomes include: skin metrics (trans epidermal water loss/TEWL, stratum corneum hydration/SCH, Sa abundance, pH, and colorimetry), pre-existing dermatological history, itch (ItchyQuant), quality of life (Skindex-mini), and RD severity (CTCAE; RISRAS). Subjects receiving standard of care RT for breast (40-60Gy over 15-30 sessions) or head/neck (H/N, 60-70Gy over 30-35 sessions) cancer complete 3 study visits: baseline (V1), end of RT (V2) and 3-months post-RT (V3). So far, 26 subjects (16 breast, 10 H/N) are actively enrolled; 14 breast and 3 H/N subjects have completed V2. Enrollment goal is 30 fully evaluable subjects. The mean age is 63±10 years, with H/N being 50% female and breast 100% female. Subjects are mainly white (92.3%), with 61.5% Fitzpatrick skin type III/IV. Among all, 21 (80.8%) had history of ≥1 skin condition (e.g. blistering sunburn, hives, contact dermatitis, atopic dermatitis, rosacea). At baseline, TEWL was higher at neck vs breast sites (mean±SD; 11.1±4.8 vs 5.7±2.1; p=0.0006) while SCH was similar across sites (neck: 22.9±10.5 vs breast: 15.7±8.5; p=0.07) and pH was lower at neck than breast (5.9±0.4 vs. 6.3±0.5; p=0.03). Sa was detectable in 34.6% of subjects at baseline (4 breast and 5 H/N), with range 106.0 to 1921.9 rCFU/cm². Results will inform future clinical trials by providing critical insight into skin barrier dysfunction and other skin related variables associated to acute RD severity. Sumeetha Swaminathan¹, Kimberly A. Arnold², Takeshi Yoshida², Anna De Benedetto², Julie Ryan Wolf² 1. School of Medicine, University of Rochester, Rochester, NY, United States. 2. Dermatology, University of Rochester, Rochester, NY, United States. Clinical Research: Epidemiology and Observational Research