OBJECTIVETo evaluate the clinical significance of CK20 mRNA expression in detecting disseminated tumor cells in peripheral blood of gastric and colorectal cancer patients.

METHODSExpression of CK20 mRNA was investigated by RT-PCR in bone marrow, portal vein and peripheral blood in 47 gastric, 58 colorectal cancer patients and 6 non-cancer volunteers. All the patients were followed-up for one year.

RESULTSThere was no positive expression of CK20 mRNA in 6 non-cancer volunteers. The positive rates of CK20 mRNA in bone marrow, portal vein were 87.2% (41/47) and 85.1% (40/47) in gastric cancer, and were 77.6% (45/58) and 74.1% (43/58) in colorectal cancer. The positive rates of CK20 mRNA in peripheral blood in gastric and colorectal cancer patients were 42.6% (20/47) and 44.8% (26/58) by one single test, and were 74.5% (35/47) and 69.0% (40/58) by two tests. The overall positive rate of CK20 mRNA in peripheral blood (two tests) was similar to that in bone marrow and portal vein. The overall positive rate of CK20 mRNA in peripheral blood was higher in two tests than in one single test (P < 0.05) and in advanced than early lesions. The relapse rate within one year was higher in CK20 mRNA positive patients than the negative ones (P < 0.05).

CONCLUSIONDetection of cancer cells by RT-PCR for CK20 mRNA in peripheral blood, being as sensitive and specific as in bone marrow and portal vein, is reliable and convenient in diagnosing micrometastasis of gastric and colorectal cancer, which possesses clinical significance in assessing the prognosis and scheme of therapy.

Adolescent ; Adult ; Aged ; Biomarkers, Tumor ; blood ; Colorectal Neoplasms ; blood ; pathology ; Female ; Humans ; Intermediate Filament Proteins ; blood ; genetics ; Keratin-20 ; Male ; Middle Aged ; Neoplasm Metastasis ; Neoplastic Cells, Circulating ; chemistry ; RNA, Neoplasm ; blood ; Reverse Transcriptase Polymerase Chain Reaction ; Stomach Neoplasms ; blood ; pathology

One hundred large bowel carcinomas were studied immunohistochemically with regard to expression of HLA-DR antigen (DR). One or two sections from each tumor including surrounding normal mucosa were examined by a semiquantitative counting system for tumor cells and mucosal and stromal infiltrates of lymphocytes and mononuclear cells (MNCs) with DR expression and the results were applied Chi-square test. The rate of presence of DR positive (DR+) lymphocytes in lymphoid nodules and DR+ lymphocytes/ MNC in the adjacent mucosa and stroma in DR+ carcinoma (50%) was higher (P < 0.01) than in DR- carcinoma (21.9%). Thirty-six carcinomas (36%) were DR+. Three (75%) out of 4 DR+ poorly differentiated carcinomas and six (20%) out of 30 DR+ moderately differentiated carcinomas showed homogeneously strong DR+ expression. There was tendency for poorly differentiated carcinoma to be more homogeneous DR+ expression. According to Dukes' stage, four (80%) out of 5 carcinomas in Dukes' stage D were DR-. An increased infiltration of lymphocytes/MNCs into adjacent mucosa and stroma in large bowel carcinomas is possibly related with DR expression by carcinoma. From the results of this study, we postulated as follows: 1) DR+ tumor cells may act as antigen-presenting cells, 2) They may have an inhibitory effect for distant metastasis, 3) Poorly differentiated carcinoma expressed more DR+ homogeneously.
Adult ; Aged ; Antibodies ; Colorectal Neoplasms/blood/*chemistry/pathology ; Epithelium/chemistry ; Female ; HLA-DR Antigens/*analysis ; Human ; Immunohistochemistry ; Leukocytes, Mononuclear/chemistry ; Lymphocytes/chemistry ; Male ; Middle Age ; Neoplasm Staging ; Support, Non-U.S. Gov't