What happened, in summary

A 61-year-old man with chronic obstructive pulmonary disease and a long smoking history was referred after wheezing and an abnormal chest X-ray. His ECOG performance status was 1, and blood tests, including carcinoembryonic antigen, cytokeratin 19 fragments, and pro-gastrin-releasing peptide, were within normal ranges. CT and PET/CT showed tumors involving the left main bronchus with left hilar lymphadenopathy, and bronchoscopy confirmed obstruction of the left main bronchus. Biopsy showed squamous cell carcinoma. The tumor was p40-positive, TTF-1-negative, and strongly PD-L1-positive, with more than 85% of tumor cells expressing PD-L1. No distant metastases were found, and the diagnosis was left lower lobe squamous cell carcinoma, cT2aN1M0, Stage IIB, with no targetable driver mutations. Because of the tumor location, the team proposed radical surgery, but the patient refused left total pneumonectomy. At his request, treatment began with transbronchoscopic tumor resection followed by pembrolizumab-based chemoimmunotherapy: carboplatin, nanoparticle albumin-bound paclitaxel, and pembrolizumab. One month later, CT showed new ground-glass opacities, consistent with grade 2 immune-related pneumonitis. The chemoimmunotherapy was stopped, and prednisolone 60 mg was started. The lung opacities resolved, and prednisolone was tapered and discontinued. The cancer had shrunk substantially, and because there was still no metastasis, he underwent sleeve resection of the left lower lobe. Surgical pathology showed a pathological complete response, meaning no viable cancer remained in the removed tissue. He had no recurrence for 1 year and 7 months after treatment and did not require additional therapy during that follow-up period. No residual treatment for pneumonitis was described after the steroid taper ended.