Conversion surgery after chemoimmunotherapy for esophageal squamous cell carcinoma with gastric intramural metastasis: a case report and the literature review

Immune checkpoint inhibitors (ICIs) have recently emerged as promising first-line treatments. Among stage IVb esophageal squamous cell carcinoma (ESCC) cases, gastric wall metastasis is rare, and conversion surgery after ICI therapy in such cases is extremely uncommon. We report a case of stage IVb ESCC with gastric intramural metastasis (IM) successfully treated with conversion surgery following ICI-based chemoimmunotherapy, along with a review of the relevant literature. A 73-year-old man was diagnosed with ESCC with gastric IM (Mt, SCC, cT3brN1M1b [IM-St], stage IVb). He received three cycles of combination immunochemotherapy with cisplatin, 5-fluorouracil, and pembrolizumab. Conversion surgery was subsequently performed. Pathological examination demonstrated a complete response, with no residual carcinoma in either the esophagus or the gastric wall. The patient remains recurrence-free 8 months postoperatively. Further studies are warranted to clarify the optimal criteria for assessing ICI treatment response and determining indications for conversion surgery in such cases.