Abstract
We examined the pathological effects of preoperative neoadjuvant chemotherapy (NAC) and the expression of markers of apoptosis, epithelial-to-mesenchymal transition (EMT) and cancer stem cells in resected pancreatic cancer specimens from patients treated with gemcitabine as NAC. Immunohistochemical expression of the apoptosis marker M30, EMT marker Snail and stem cell marker CD44 in surgically resected pancreatic cancer specimens were compared between patients treated (NAC group n=13) and not treated (control group n=21) with gemcitabine. In the NAC group, the tumor specimens showed tumor cell injury; however, there was no significant reduction of serosal, retroperitoneal, perineural or vascular invasion, lymph node metastasis or tumor size. The expression frequencies of M30 and CD44 were significantly higher in the NAC group (61.5 and 53.8%) compared to the control group (9.5 and 14.3%); however, no significant difference in Snail expression was noted between the two groups (53.8 versus 42.9%). Gemcitabine induced apoptosis of pancreatic cancer cells in vivo; however, it did not reduce the tumor burden. Moreover, the residual cancer tissues were rich in chemoresistant cancer stem cells. By contrast, marked EMT of cancer cells was observed in the specimens from the groups treated and not treated with gemcitabine.