Comparative analysis of polymerase chain reaction and conventional cytological examination for peritoneal recurpence risk assessment patients undergoing surgery for colorectal cancer
A. Revura, M. Fetsych
Department of Oncology and Radiology, Danylo Halytskyy Lviv National Medical University, Lviv, Ukraine
Introduction: Peritoneal recurrence is a major cause of surgical treatment failure in patients with colorectal cancer (CRC). Diffuse metachronous peritoneal carcinomatosis is associated with poor prognosis and median survival of 5–6 months. There is a chance for prolongation of survival in patients with limited peritoneal carcinomatosis who are eligible for aggressive combined treatment. Evaluation of peritoneal relapse risk at a time of surgery for primary colorectal tumor is essential for early diagnosis and treatment of metastasis. The presence of free cancerous cells (FCC) within the peritoneal cavity is believed to be a powerful predictor of peritoneal carcinomatosis. A method of real-time polymerase chain reaction (PCR) was proposed recently to detect FCC in peritoneal washes. Aim: To evaluate the feasibility of real-time PCR for detection of FCC within the peritoneal cavity of patients with CRC who underwent curative surgery and to compare the results with those of conventional cytology. Patients and Methods: Twenty-two patients were enrolled in this study with ethical considerations. Patients were divided into three groups. The main group consisted of 16 patients radically operated for CRC. Positive control group included three patients with macroscopic peritoneal carcinomatosis diagnosed at a time of surgery for CRC. Negative control group consisted of three patients with benign colorectal tumors. A laparotomy and subsequent peritoneal lavage were performed in all 22 patients. Peritoneal wash samples were analyzed microscopically by Giemsa staining and by PCR analysis with primers for carcinoembryonic antigen (CEA) gene as a molecular target of cancerous cells. Real-time thermal cycler “Bio-Rad iCycler iQ5” (USA), PCR reagent kits “Fermentas” (Lithuania) and oligonucleotide primers “Metabion” (Germany) were used. Cases with CEA signal were defined as PCR-positive. Results: PCR reaction was positive in three (19%) of 16 patients in the main group, while cytology was negative in all samples. No positive results of PCR and cytology in negative control group was detected, i.e. both methods yielded no false-positive results. Cytological examination was positive only in one (33%) of three patients of positive control group showing lack of sensitivity, whereas all (100%) of them were PCR-positive. Conclusions: CEA identification by PCR appears to be reliable method of FCC detection. It can be useful for identifying patients at high risk of peritoneal relapses of colon cancer following primary tumor resection. PCR is a more sensitive method for FCC detection in peritoneal washes compared to conventional cytology.
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