title: Clinical significance of cytokeratin 20-positive circulating tumor cells detected by a refined immunomagnetic enrichment assay in colorectal cancer patients.
abstract: OBJECTIVE
  Current immunomagnetic enrichment method can only detect general epithelial antigens of circulating tumor cells (CTC). Further characterization of the CTCs to provide specific information on the tumor type is not possible. We attempted to overcome this drawback by developing the methodology for using a gastrointestinal-specific anti-cytokeratin (CK) 20 antibody to detect CTCs in colorectal cancer patients' blood.
  
  
  METHODS
  The protocol was validated using a colorectal cancer SW480 cell line. The clinical significance of findings in colorectal cancer was investigated by detecting CK20-positive CTCs (pCTC) in patients with colorectal cancer, other common cancers, colorectal adenoma, benign colorectal diseases, and normal subjects. Moreover, the malignant nature of CK20 pCTCs was examined by comparing chromosome 17 aberration patterns with those from the corresponding primary tumors.
  
  
  RESULTS
  The assay successfully showed CK20-positive SW480 cells. When applied in patient samples, the detection rates were 62% (132 colorectal cancer patients; median number = 11 CTCs), 0% (120 patients with other common cancers), 6% (50 colorectal adenoma patients), 0% (120 patients with benign colorectal diseases), and 0% (40 normal subjects). Furthermore, statistical analysis showed that CK20 pCTC numbers were associated with tumor-node-metastasis stage and lymph node status. Using the median CK20 pCTC numbers as the cutoff points, stratified groups of colorectal cancer patients had significant differences in their recurrence, metastasis, and survival. Finally, chromosome 17 aneusomy in 90% of colorectal cancer patients with CK20 pCTCs matched with those from the primary tumors.
  
  
  CONCLUSIONS
  Detection of CK20 pCTCs using the new protocol could generate clinically important information for colorectal cancer patients.
authors.affiliation: State Key Laboratory in Oncology in South China, Sir Y.K. Pao Centre for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Prince of Wales Hospital, People's Republic of China. cesar01@netvigator.com
authors.forename: Sze Chuen Cesar
authors.initials: SC
authors.lastname: Wong
authors.forename: Charles Ming Lok
authors.initials: CM
authors.lastname: Chan
authors.forename: Brigette Buig Yue
authors.initials: BB
authors.lastname: Ma
authors.forename: Edwin Pun
authors.initials: EP
authors.lastname: Hui
authors.forename: Simon Siu Man
authors.initials: SS
authors.lastname: Ng
authors.forename: Paul Bo San
authors.initials: PB
authors.lastname: Lai
authors.forename: Moon Tong
authors.initials: MT
authors.lastname: Cheung
authors.forename: Elena Siu Fong
authors.initials: ES
authors.lastname: Lo
authors.forename: Amanda Kit Ching
authors.initials: AK
authors.lastname: Chan
authors.forename: Money Yan Yee
authors.initials: MY
authors.lastname: Lam
authors.forename: Thomas Chi Chuen
authors.initials: TC
authors.lastname: Au
authors.forename: Anthony Tak Cheung
authors.initials: AT
authors.lastname: Chan
mesh_terms: D000236:Adenoma / Q000097:blood; D014408:Biomarkers, Tumor / Q000097:blood; D045744:Cell Line, Tumor; D002886:Chromosomes, Human, Pair 17; D015179:Colorectal Neoplasms / Q000097:blood* / Q000235:genetics; D006801:Humans; D018189:Immunomagnetic Separation / Q000379:methods*; D053554:Keratin-20 / Q000097:blood*; D009360:Neoplastic Cells, Circulating / Q000737:chemistry*; D011379:Prognosis
chemical_list: D014408:Biomarkers, Tumor; D053554:Keratin-20