Intriguingly, recent studies showed that the levels of some cancer markers, including carcinoembryonic antigen (CEA), carbohydrate antigens (CA) 125 and 153, squamous cell carcinoma antigen (SCCA), and cytokeratin-19 fragment (CYFRA21-1), were elevated in COVID-19 patients and were correlated with the severity of COVID-19 (137, 138). Here, CEACAM5 is linked to cancer.