Prognostičko značenje izražaja gena za citokeratin-20 u stanicama periferne krvi bolesnika s rakom debeloga crijeva [Cytokeratin-20 positive cells in blood of colorectal cancer patients as a prognostic marker]

Cytokeratin 20 (CK20) is one of the most investigated markers for the detection of circulating cancer cells. Detection of circulating cancer cells by reverse transcription polymerase chain reaction (RT-PCR) was studied as prognostic marker in colorectal cancer patients in several studies, but so far with conflicting results regarding its prognostic value. Primary aim of this study was to evaluate prognostic value of RTPCR detection of circulating colorectal cancer cells using CK20 as a marker. Ribonucleic acid (RNA) was isolated from mononuclear cell fraction of blood samples taken from 95 colorectal cancer patients before and after tumor resection, and from 23 healthy volunteers, and assayed by real-time RT-PCR for CK20 expression. Among 23 healthy volunteers, seven were positive for CK20. Among 95 colorectal cancer patients, 69 were positive for CK20 before, and 74 after surgery. Fifteen patients positive before surgery became negative after surgery, while 20 patients negative before surgery became positive after surgery. Increase in the proportion of CK20 positive samples with increasing stage of disease was observed for postoperative, but not for preoperative blood samples. In patients positive for CK20 postoperatively, both progression-free survival (PFS) and overall survival (OS) were statistically significantly shorter in comparison to patients negative for CK20 postoperatively and difference between patients CK20 positive and negative preoperatively was not statistically significant in terms neither PFS nor OS. Our results have shown that CK20 as marker for detection of circulating cancer cells has a prognostic value in colorectal cancer patients. In cases where multiple treatment options are possible, patients with positive postoperative CK20 expression could be candidates for more aggressive treatment