RESUMEN
Colorectal carcinoma [CRC] is one of the most common malignancies. Inspire of successful resection of the primary Tumour, metastasis is one of the most important factors determining the patient's prognosis. The present study was initiated to detect disseminated cancer cells in LNs and peripheral blood of patient's with CRC via detection of cytokeratin 20 [CK20] mRNA expression by conventional and real time reverse transcriptase polymerase chain reaction [RT-PCR]. This study included 34 patients with early stage CRC who have undergone total tumor resection, and were proved to be node negative histopathology. The study also included two control groups; a pathological control group [n = 10] suffering from ulcerative colitis and a healthy control group [n = 21], who have undergone pelvic repair for rectal prolapse and were otherwise completely free. For all subjects, serum CEA was measured in addition to cull routine laboratory investigations. Conventional PCR for detection of CK20 mRNA was [lone in both peripheral blood and lymph node samples for all participants. Whereas, quantitative real time RT-PCR for detection of CK20 mRNA was done for lymph node samples of the patient group only. Results of' the present study showed that all peripheral blood samples tested by conventional PCR were consistently negative for CK20 mRNA expression, whereas, mRNA was detected in the LN tissues of 16 of the 34 patients included in this study. Quantitative real-time RT-PCR appeared to be more sensitive than conventional PCR as it was able to detect CK20 mRNA in 20 out of the 34 patients included in this study. Based on the results of our realtime PCR, time patient group was divided into 20 patients with detectable mRNA and 14 with undetectable CK20 mRNA. The results of CEA levels were elevated in the former goup than time latter one, however this elevation was not statistically significant. on comparing nodal expression of CK20 mRNA in different histologic tumour types, 85. 7% of mucinous carcinoma patients showed nodal expression versus 51.9% of adenocarcinoma patients. Patients with Dukes' stag B2 showed 92.8% nodal expression versus only 35% patients with Dukes' B1 stage. Poorly differentiated tumours showed 100% nodal expression of CK20 mRNA versus 38.1% for time moderately differentiated and 66.7% for the well differentiated tumour group. In conclusion, CK20 mRNA is a valuable tool for monitoring early stage dissemination of CRC malignant cells. Real time PCR provides a more sensitive and reliable technique for detection of' disseminated cancer cells in CRC patients than the traditional PCR technique. Besides, CK20 mRNA is a promising predictor of poor prognosis being increased in mucinous, poorly differentiated and Dukes' B2 CRC patients