Another platform is the cytology-based filtration method that has the possibility to detect any tumour surface markers on cancer cells, epithelial and non-epithelial, and distinguish between single CTC and CTC clusters [46], whereas most other CTC technologies, such as AdnaTest or Cellsearch, critically rely on the epithelial cell adhesion molecule (EpCAM) marker, limiting their applicability for early-stage PC where CTCs may not have developed epithelial characteristics. This evidence concerns the gene EPCAM and pachyonychia congenita.