title: Detection of cytokeratin-20-positive cells in preoperative and postoperative blood samples from colorectal cancer patients by real-time RT-PCR.
abstract: BACKGROUND
  Detection of circulating cancer cells by reverse transcription polymerase chain reaction (RT-PCR) has been studied as a prognostic marker in patients with colorectal cancer (CRC) but so far with conflicting results regarding specificity and prognostic value. In this study cytokeratin-20 (CK20) was evaluated by real-time RT-PCR as a marker for circulating CRC cell detection and the influence of surgical tumor resection on the presence of circulating CRC cells was analyzed.
  
  
  METHODS
  RNA was isolated from the mononuclear cell fraction of blood samples taken from 95 CRC patients before and after tumor resection and from 23 healthy volunteers and assayed by real-time RT-PCR for CK20 expression.
  
  
  RESULTS
  Among 23 healthy volunteers one was positive for CK20. Among 95 CRC patients, 25 were positive for CK20 before and 23 after surgery. Sixteen patients positive before surgery became negative after surgery, while 14 patients negative before surgery became positive after surgery. An increase in the proportion of CK20-positive samples with increasing stage of disease was observed for preoperative but not postoperative blood samples.
  
  
  CONCLUSIONS
  Its association with clinical stage indicates that CK20 might have prognostic value as a marker for detection of circulating CRC cells. Surgical tumor resection can both reduce and induce the presence of circulating CRC cells.
authors.affiliation: Department of Oncology and Nuclear Medicine, University Hospital Center Sestre milosrdnice, Zagreb, Croatia. ivan.samija@kbcsm.hr
authors.forename: Ivan
authors.initials: I
authors.lastname: Šamija
authors.forename: Josip
authors.initials: J
authors.lastname: Lukač
authors.forename: Mirjana Končar
authors.initials: MK
authors.lastname: Mubrin
authors.forename: Iva
authors.initials: I
authors.lastname: Kirac
authors.forename: Dujo
authors.initials: D
authors.lastname: Kovačević
authors.forename: Zvonko
authors.initials: Z
authors.lastname: Kusić
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood*; D015179:Colorectal Neoplasms / Q000097:blood* / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D053554:Keratin-20 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009360:Neoplastic Cells, Circulating; D011184:Postoperative Period; D057234:Preoperative Period; D011379:Prognosis; D012333:RNA, Messenger / Q000097:blood / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D014408:Biomarkers, Tumor; D053554:Keratin-20; D012333:RNA, Messenger