Complete Response to Chemo-Immunotherapy in Recurrent Unresectable Tracheal Squamous Cell Carcinoma: A Case Report.

Primary malignant tumors of the trachea are rare, with squamous cell carcinoma (SCC) being the most frequent subtype. Due to limited data, optimal systemic therapy for unresectable or recurrent cases remains undefined. We report a case of recurrent primary tracheal SCC achieving durable complete remission with immune checkpoint inhibitor (ICI)-based combination chemotherapy. A 73-year-old man with a history of resected lung cancer was incidentally diagnosed with tracheal SCC. Following bronchoscopic tumor debulking, he underwent concurrent chemoradiotherapy. Recurrence with pulmonary metastases occurred 4 months later. He was treated with four cycles of pembrolizumab plus nab-paclitaxel and carboplatin, followed by pembrolizumab maintenance. Complete radiologic remission was achieved and sustained for over two years. This case highlights the potential of ICI-based regimens, widely used in non-small cell lung cancer, as a promising option for recurrent tracheal SCC. Multidisciplinary approaches incorporating immunotherapy may offer meaningful benefit in this rare malignancy.