Although there have been more studies reporting an association between pre-existing ILD and ICI-related pneumonitis than those that did not detect the association, the definition of pre-existing ILD investigated in each study differ, and considering a possible publication bias toward studies that demonstrated significance, there has been no clear consensus yet on whether pre-existing ILA or ILD is a risk factor for ICI-related pneumonitis. This evidence concerns the gene TNFRSF9 and pneumonitis.