Comment on "Elevation of Serum Carcinoembryonic Antigen Concentration Caused by Everolimus-Induced Lung Injury: A Case Report".

We read with great interest the report of elevated serum carcinoembryonic antigen (CEA) following everolimus administration,1) in which it was reported that everolimus treatment for renal cell carcinoma with lung metastasis caused pulmonary ground-glass opacities accompanied by elevated serum CEA. Furthermore, interrupting everolimus resulted in improvements of both lung shadows and elevated CEA levels. As there have been no reports of correlations between everolimus and elevated CEA to date, the authors concluded that the elevated CEA could be caused by everolimus-induced lung injury. CEA is one of the most widely used tumor markers, and serum CEA levels increase in gastrointestinal cancers, as well as other types of carcinomas. However, serum CEA also rises in non-neoplastic conditions, such as inflammatory diseases of the glandular epithelium, biliary obstruction, and metabolic disorders including hyperglycemia.2) Among these metabolic disorders, hypothyroidism is a frequent endocrinological disorder associated with elevated Comment on “Elevation of Serum Carcinoembryonic Antigen Concentration Caused by Everolimus-Induced Lung Injury: A Case Report”