PROM1 and vulva cancer: Considering CD133 expression, all patients with vulvar cancer with numbers of CD133+ CTCs ≥ 14/ml developed relapse after 67 months, while numbers of pan-cytokeratin+ CD45− CTCs ≥ 7/ml, without examination of CD133 expression, resulted in 6.5-year RFS rate of 18.2% as shown before (Fig. 2G; Supplementary S3A).