Pembrolizumab plus Chemotherapy for Synchronous Multiple Primary Esophageal and Gingival Squamous Cell Carcinomas

Background/aim Immune checkpoint inhibitors are effective treatments for a variety of malignancies. However, evidence supporting their use in patients with multiple primary cancers remains limited because these patients are typically excluded from clinical trials.Case report We report the case of a 68-year-old man with synchronous squamous cell carcinomas of the esophagus and mandibular gingiva, both with a combined positive score of ≥1 and Conclusion The mechanisms underlying the favorable response remain unclear and may involve factors beyond conventional tumor biomarkers. This case suggests that PD-1 blockade provides a substantial clinical benefit in select patients with multiple primary cancers.