Depth-oriented organ-preserving salvage endoscopic strategy with argon plasma coagulation and photodynamic therapy for residual or recurrent esophageal squamous cell carcinoma after chemoradiotherapy

A salvage endoscopic strategy applying APC for ycT1a and PDT for ycT1b-T2, with flexibility based on tumor depth, is feasible, safe, and effective. Tailoring treatment to invasion depth may optimize organ preservation and local control in residual or recurrent ESCC after CRT.