Compared to IL-8 assay, CD31 detection had much lower diagnostic sensitivity and specificity in distinguishing thymomas from other types of thymic tumors (Supplementary Fig. 4b, c); PTK7 or CR2 assay also showed lower discriminatory ability in thymoma diagnosis, only with AUC level 85% and 84%, respectively (Supplementary Fig. 6 and 7). Here, PTK7 is linked to thymoma.