Multiple lung cancers including squamous cell carcinoma with strong PD-L1 expression and adenocarcinoma with EGFR exon 19 deletion: A case report.

We herein report a non-smoking 81-year-old man with advanced synchronous multiple primary lung cancers (SMPLC), containing squamous cell carcinoma with strong programmed death-ligand 1 expression in the middle lobe and adenocarcinoma with epidermal growth factor receptor (EGFR) exon 19 deletion in the lower lobe. Programmed death-1 (PD-1) inhibitors were administered as first-line chemotherapy; however, treatment response was poor response. There have been no reported SMPLC cases similar to this. During treatment, his non-smoking status and EGFR deletion might have been the cause of the patient's poor response to first-line PD-1 inhibitor treatment.