Radiation-Induced Skin Injury

This study is a multicenter, open-label, Phase I single-arm clinical trial evaluating the safety and tolerability of a topical AKK probiotic preparation (Akkermansia muciniphila) for the prevention and treatment of radiation-induced skin injury in patients receiving radiotherapy for breast cancer, head and neck cancer (including nasopharyngeal carcinoma). A total of 40 participants are planned to receive the AKK preparation applied to the radiation field three times daily, starting one day before the first radiotherapy fraction and continuing until 14 days after the last fraction. The primary outcome is the incidence of grade ≥2 acute radiation dermatitis (ARD) assessed by RTOG and CTCAE criteria. Secondary outcomes include changes in skin micro-features under digital dermoscopy, skin microbiota composition, quality of life (Skindex-16), and safety.