Supplementary Material for: Synchronous double primary malignancy of non-small cell lung cancer and glioblastoma: A case report and literature review

Background: Non-small cell lung cancer (NSCLC) is the most common form of lung cancer and has a propensity to metastasize to the brain. It is incredibly difficult to distinguish between a primary brain lesions and a solitary metastasis from distant occult disease using current imaging techniques. Further, complications arise from the shifting paradigm in how medicine views NSCLC brain metastasis due to contemporary non-surgical curative treatments and the recent increase in the number of multiple primary malignancy (MPM) diagnoses associated with NSCLC. There is a dearth of reports regarding synchronous double primary malignancies involving separate lung and brain pathologies. Importantly, understanding the underlying cancer etiology is necessary for efficacious treatment strategy. Case Presentation: A 65-year-old white male patient presented with node-positive NSCLC and a solitary intracranial lesion. The lung mass responded favorably to chemoradiotherapy while the brain lesion continued to progress despite stereotactic radiosurgery treatment. Subsequent resection of the brain lesion, conducted eight months after initial presentation, surprisingly revealed a second primary cancer diagnosis of glioblastoma (GB). Unfortunately, despite revision of systemic therapeutic strategy, the patient continued to progress through treatment and ultimately died 16 months after the initial diagnosis. Conclusions: Herein is the third report regarding synchronous double primary malignancies involving non-small cell lung cancer NSCLC and GB. This report of an assumed metastatic NSCLC patient with a solitary brain lesion, history of smoking, and COPD underscores the need for pathological confirmation of all new presentations of metastatic disease via biopsy and highlights the importance of including the possibility of a second primary in the differential diagnosis. Additional reports of NSCLC and synchronous solitary brain lesions are needed to further elucidate pertinent patient characteristics and better inform clinical decision making.