Background & objective: Most results from clinical trials of neoadjuvant chemotherapy for gastric carcinoma are certain. Meanwhile, microsatellite instability (MSI) is thought to be a new mechanism of cell canceration. This study was to investigate the influence of neoadjuvant chemotherapy on MSI in gastric carcinoma.
Methods: Two microsatellite loci D2S123 and D3S1298 in tumor samples from 48 patients with gastric carcinoma, received preoperative chemotherapy of 5-fluorouracil (5-FU) and leucovorin (CF), were analyzed by polymerase chain reaction (PCR), electrophoresis on 8% denatured polyacrylamide gel, and silver staining. The microsatellite statuses of preoperative and postoperative specimens were compared. Chi-square test was used to analyze the influence of neoadjuvant chemotherapy on MSI in gastric carcinoma.
Results: The detection rate of MSI was significantly higher in preoperative samples than in postoperative samples (31.3% vs. 12.5%, P=0.026). After neoadjuvant chemotherapy, 9 cases changed from MSI-positive to MSI-negative, while no MSI-negative cases became MSI-positive.
Conclusion: The neoadjuvant chemotherapy regimen of 5-FU/CF can induce some MSI-positive gastric carcinoma change to MSI-negative, but has no effect on MSI-negative cases.