Abstract
Multiple primary lung cancers (MPLCs), characterized by the presence of more than one distinct primary lung tumors, may develop either synchronously (simultaneously) or metachronously (after initial cancer treatment). This case describes a rare occurrence of three primary lung cancers in a chronic smoker. After a lobectomy for right middle lobe adenocarcinoma (ADC), the patient was diagnosed with synchronous small cell carcinoma (SCLC) in the right upper lobe and squamous cell carcinoma (SCC) in the right lower lobe. Notably, the ADC and subsequent lung cancers were metachronous. Due to her unsuitability for surgery, the patient pursued a treatment regimen involving radiation therapy, chemotherapy, and immunotherapy. This case underscores the need for vigilant identification and comprehensive management of MPLCs, particularly in high-risk patients, to improve outcomes and reduce the burden of this rare condition.