Basic And Clinical Studies On The Laterally Spreading Tumor Of Large Intestine

Background/ObjectivesLSTs (Laterally spreading tumors) are promontory tumors originated from the colorectal mucous membranes. LST was characterized by that the tumors are larger than 1 cm in diameters, and by that the tumors grow laterally rather than vertically. Therefore, LST is a morphological definition of tumors. LST differs from other colorectal adenomas both morphologically and pathologically and has been suggested to develop to colorectal cancer with higher potential. Up to now, few reports on the colorectal LST have been available in China. Current investigations aim to elucidate the biological features of LST.Methods1. Patients with the polypi were examined with colonoscopy and mucosa staining.2. The pit patterns (according to Kudo's classification) were visualized with a magnifying endoscope and a stereomicroscope and then compare the relations between the pit pattern and pathologic diagnoses.3. LST cell strain was established using standard primary cell culture techniques.4. Gene expressions of some colon cancer related oncogenes as well astumor suppressor genes were determined by tissue in situ hybridization and immunohistochemistry.Results1. The pit patterns found in LST were mainly the type III or IV according to Kudo's classification. In these groups, pit patterns observed under magnifying endoscope highly correlated to what observed under stereomicroscope.2. The LST cell strain derived from villous adenoma displayed various atypical hyperplasia. The LST cells showed similar characteristics to the tumor cells in cell growth behavior and cellular ultrastructure.3. Oncogenes and tumor-suppressor genes tested in the current study showed expression at different levels in LST cells.Conclusions1. Pit patterns are very important to visualize the tumorous lesions and non-turnorous lesions and to help to find out the early colorectal cancer. Pit pattern V possibly indicates the early development of cancers. LST usually displays the pit patterns of III and IV.2. We established a strain of LST cell that behaved like malignant colorectal tumor cells.3. LST displayed similar oncogene and tumor-suppressor gene expression patterns as the colorectal tumors.