PTPRC and head and neck squamous cell carcinoma: CTCs were enriched by CD45 depletion and then analyzed by flow cytometry in 84 blood samples from 48 epithelial cancer patients (10 breast, 11 colon, 3 gastric, 6 ovarian, 7 cervix, 3 NSCLC and 8 SCCHN) and in 32 samples from 22 metastatic melanoma patients.