Study On CD-DST Method For Detecting The Sensitivity Of Microsatellite Instability Type Gastric Cancer To Some 5-FU Containing Adjuvant Chemotherapy

Objective:Aim to detect the sensitivity of microsatellite instable type gastric cancer to the chemotherapy 5-FU+Topotecan;5FU+L-OHP;5-FU by the CD-DST method.Methods:We analyzed data from 83 patinets adopted by the China Japan Union Hospital of Jilin University Department of gastrointestinal surgery,who were determined gastric cancer by pathology. We gather the tumor cells and tumor adjacent normal mucosa tissue from the 83 patients. Then test the microsatellite stability of the tumor cells, by testing five micro satellite detection bat-25, BAT-26, d5s346, d2s123,d17s250 microsate-llite loci. Classify all the tumor into three group : microsatellite instability high(MSI-H) gastric cancer, low microsatellite instability(MSI) gastric cancer, micro microsatellite instability(MSS) in gastric cancer. After that,We detect the sensitivity differences between MSI-H group and MSS gruop to the chemotherapy 5-FU+Topotecan;5FU+L-OHP;5-FU by the CD-DST method.(We do not test the MSI-L group,because the number of MSI-L group only three,take them into the study may lead to error conclusion.)Results:By MSI detection, We dignose 16 cases of high microsatellite instable type(MSI-H type) gastric cancer, in 3 cases of low microsate-llite instability type(MSI-L type)gastric cancer, 64 cases of microse-tellite stability(MSS) gastric cancer. 5-FU monotherapy for the average inhibition rate of MSI-H was 87.7 + 7.4%,lower than the 5-FU for the MSS group the average inhibition rate(81.3 + 10.3%)(P=0.018), the difference was statistically significant. Oxaliplatin combined with5-FU for inhibition of two groups of MSI-H and MSS rate was 60.7 + 6.3%, 62.6 +12.1, the gap is not statistically significant(P = 0.46), topotecan combined with 5-FU scheme for inhibition of MSI-H and MSS rate was 59.3 + 7.3%, 56.4 + 9.1%, the gap is not statistical significance( P=0.144).Conclusion:This study showed that MSI-H type gastric cancer compared with MSS type gastric cancer is less susceptible to 5-FU single drug chemo-therapy. Although in the two combination regimens MSI and MSS gastric cancer showed no differences,but in view of the different sensitivity between two groups to 5-FU, the question if MSI-H gastric cancer is suitable for use of 5-FU combined with oxaliplatin or Topotecan chemotherapy there are still questions to be further larger sample study.