ITGA5 and lung cancer: Whereas prior studies about lung cancer were able to show a significant relationship between COL5A2, ITGA5, ITGAV, and ITGB1 gene expression only in non-small cell lung cancer (54–58), our results suggest that COL5A2, ITGA5, and ITGB1 expression in PNENs, used as co-dependent variables, provide more information about the risk of metastasis and overall survival than does pathological stage.