Complete remission after concurrent single-agent S-1 chemoradiotherapy for stage IIIB esophageal cancer: an autopsy case report.

Chemoradiotherapy regimens for patients with esophageal cancer intolerant to standard therapies remain to be established. The standard therapy for patients with stage II-III esophageal squamous cell carcinoma, who are not surgical candidates, is definitive chemoradiotherapy with concomitant use of 5-fluorouracil and cisplatin; however, cisplatin can cause serious adverse events. An 83-year-old Japanese man developed a 2-month history of nausea and vomiting. Contrast-enhanced computed tomography revealed concentric wall thickening in the mid-to-lower esophagus with surrounding regional lymph node swelling. Upper gastrointestinal endoscopy revealed an ulcerated tumor with raised margins in the middle esophagus. He was diagnosed with stage IIIB (T3N2M0) esophageal squamous cell carcinoma, pathologically exhibiting squamous epithelium-like invasive abnormal structure with atypical cells. He underwent chemoradiotherapy involving four-dimensional conformal radiotherapy and single-agent S-1 rather than the standard chemoradiotherapy, and achieved clinical remission 2 months later on endoscopy and computed tomography. The patient died 1 year later due to pneumonia, and the autopsy did not reveal any evidence of squamous cell carcinoma in the esophagus, surrounding lymph nodes, or other organs, suggesting pathologically complete remission. Concurrent single-agent S-1 chemoradiotherapy may induce complete remission of stage IIIB esophageal cancer and is a possible alternative for older patients or those with multiple comorbidities.