Gastrointestinal Stromal Tumors; Clinicopathological Features and Prognostic Factors

PURPOSE: Gastrointestinal stromal tumors (GIST) are a heterogenous group of mesenchymal neoplasms of the gastrointestinal tract. This study was performed to determine the clinical characteristics and prognostic factors of GIST. METHODS: We studied 24 cases of GIST collected over a 9 year period. This retrospective review analyzed the clinical presentation, pathologic examination, and long-term follow-up of patients with GIST. The clinicopathological features were evaluated to identify the predictors of survival. RESULTS: The most common clinical presentation was pain or discomfort (37.5%). GISTs were found to be typically present in older individuals and be most common in the stomach (41.7%). All patients underwent surgical resection with curative intent. The follow-up period ranged from 3 to 110 months. Recurrence occurred in 11 (45.8%) of 24 patients. According to multivariate analysis, survival was inversely correlated with size (P=0.032) and the number of mitoses (P=0.030). Patients younger than 50 had an independent value for prognostic prediction (P=0.058). CONCLUSION: Tumor size, mitotic index and patient's age can be used as prognostic factors for GIST according to the results of our study. But, better pathological and immunohistochemical methods are still required to improve GIST prognosis.

The moment generated by the torque of the orthodontic rectangular wire : Three-dimensional finite element analysis / 대한치과교정학회지

The purpose of this study was to investigate the ideal clinical torque(In the SWA rectangular wire, the torque by the angle between the plane part and twisted part to move the tooth) of the orthodontic rectangular wire which produce the proper labiolingual movement of the single tooth during finishing stage of the orthodontic treatment. The clinical torque is the sum of the play and the active torque which generates the moment at the bracket. The play is calculated by the formula and the active torque is calculated by the computer aided three-dimensional finite element method. The finite element model was consist of the three brackets which formed a row and 3 kinds of orthodontic rectangular wire(stainless steel, TMA, NiTi) which inserted in brackets. Both sides of the model were twisted and the moment generated in the center bracket was calculated. The sizes of seven wires which were used commonly were .016" X .022", .017" X .022", .017" X .025", .018" X .025", .019" X .025", .020" X .025", .021" X .025". In 018" bracket, 016" X .022", .017" X .022", .017" X .025" wires were inserted and in 022" bracket, all the sizes of wires except .016" X .022" were inserted and tested. The following conclusions could be drawn from this study. 1. The moments generated on the same size of the wires by the same active torque were equal regardless of the bracket slot size. 2. The moments were increased with the size of the wires. The moment generated on the .021" X .025" wire was about 1.75 times as large as that on the .016" X .022" wire regardless of the material. 3. The moments were increased in the order of the NiTi, TMA, stainless steel. The moment of the TMA wire was 0.35 times as small as that of the stainless steel wire and the moment of the NiTi was 0.16 times as small as that of the stainless steel wire. 4. The moment was decreased as the interbracket distance was increased. 5. To get a desired moment with the specific size and material of the wire on the specific bracket slot, the formula and the results were displayed.

Expression of Thymidylate Synthase in Gastric Cancer

PURPOSE: 5-fluorouracil is one of the widely used chemotherapeutic agent whose metabolic product forms tight covalent binding complex with thymidylate synthase (TS) and thereby blocks the DNA synthesis process. Expression of TS has been studied as a mechanism of drug resistance and as a prognostic factor for various cancers. METHODS: The relation between TS expression in surgically resected specimens and clinicopathologic features was examined in 62 patients with gastric cancer. Immuno histochemical demonstration of the protein was achieved using an anti-TS monoclonal antibody. RESULTS: In Lauren's classification, TS expressions of the intestinal type and the diffuse type were 21.93% and 14.96% respectively (P=0.02). And TS expression in a group with lymphatic invasion was higher (26.15%) than that in a group without lymphatic invasion (16.15%)(P=0.0001). There were no significant differences between the TS expressions associated with other clinicopathologic features (P>0.05). CONCLUSION: For the purpose of assessing the applicability of TS expression as a prognostic factor and as a mechanism for drug resistance, assessment of TS expression must be standardized. Although direct correlations between TS expression and other clinicopathologic features were found only in Lauren's classification and lymphatic invasion, further investigations of the relation between TS expression and drug resistance of 5-FU must be continued to provide data for choosing chemotherapuetic agents for use in patients with gastric cancer.