ACE2 and lung cancer: This study presents several limitations: (i) high ACE2 levels are considered a surrogate for susceptibility to COVID-19 infection, and therefore further work would need to be performed in patients who later did or did not become infected; (ii) we could not determine whether ACE2 expression is higher in the normal lung of lung cancer patients than in individuals without lung cancer and whether such a difference might be the reason why patients are vulnerable to COVID-19; and (iii) patients with resectable and metastatic NSCLC are from different studies.