Durable Complete Response to Immunotherapy-Integrated Chemoradiotherapy in Esophageal Squamous Cell Carcinoma with Direct Liver Invasion and Treatment-Emergent Tumor–Gastric Fistula: A Case Report

Direct hepatic invasion is an uncommon presentation of esophageal squamous cell carcinoma (ESCC), and evidence guiding chemoradiotherapy in this setting is limited. A 59-year-old man presented with middle-to-lower thoracic ESCC extending through the esophagogastric junction and gastric cardia, with direct hepatic invasion. Extensive regional nodal disease and a solitary right supraclavicular nonregional nodal metastasis supported cT4bN3M1 stage IVB disease, with high PD-L1 expression. The patient received curative-intent radiotherapy with concurrent cisplatin, paclitaxel, and nivolumab. The planned radiotherapy dose was 50.4 Gy in 28 fractions to the esophageal and regional lymph node volume, with a simultaneous integrated boost to the gross tumor and gross lymph nodes to 56 Gy in 28 fractions, followed by a sequential boost to the supraclavicular lymph node to a total 66 Gy in 33 fractions. After the 25th fraction, computed tomography results demonstrated contained tumor–gastric fistulization without pneumoperitoneum; therefore, the remaining three fractions to the esophageal and regional volumes were not delivered. The delivered doses were 45 Gy to these volumes and 50 Gy to the gross disease, each in 25 fractions. A conservative treatment strategy was initiated, including withholding oral intake, administering intravenous antimicrobial therapy, and continuing jejunal enteral feeding. Maintenance nivolumab with infusional 5-fluorouracil was continued for more than three years as an individualized strategy not based on an established prospective trial regimen. With pathological diagnosis designated as Month 0, positron emission tomography/computed tomography demonstrated complete metabolic response at Month 4, with no recurrent or metastatic disease on follow-up examinations through Month 44 during ongoing maintenance therapy. This case highlights durable disease control after immunotherapy-integrated chemoradiotherapy in advanced ESCC with initial direct liver invasion and the value of individualized treatment adaptation when tumor–gastric fistulization develops.