It is possible to detect the tumor cells in the peripheral blood, lymphonodi and bone marrow at mRNA level by using RT‐PCR technique.18, 19, 20, 21 But its clinical application is limited, because negative results can be caused by the absence of some tumor specific genes expression due to the heterogeneity of tumor.22, 23 To study whether cdc6 could be used as a circulating tumor cell marker with RT‐qPCR technique, we probed the RNA‐seq data from gene browser at Dr Wang zhibin's laboratory of John Hopkins University. This evidence concerns the gene CDC6 and neoplasm.