Pancreatic metastases

Direct laparoscopic visualization of the peritoneum, omentum, and liver surface can spare patients unnecessary surgery. Once a pancreatic mass is considered to be unresectable or if metastasis occurs, then a histologic diagnosis should be established by using direct fine-needle aspiration. 

Gallo-Hendrikx E., Copps J., Percy D., Croy B. A. and Wildeman A. G. (1994). Enhancement of pancreatic tumor metastasis in transgenic immunodeficient mice. Oncogene 9, 2983-2990. 

These highly aggressive and rapidly fatal tumors constitute less than 1% of all pancreatic endocrine neoplasms. They are so uncommon that some authors believe a poorly differentiated neuroendocrine carcinoma occurring in the pancreas is most likely a metastasis from an occult primary in the lung. However, there are proven cases of primary in this region." " Many are in fact of ampullary origin, and few are pancreatic. 

Koshiba T, Hosotani R, Wada M, et al. Involvement of matrix metalloproteinase-2 activity in invasion and metastasis of pancreatic carcinoma. Cancer. 1998 82 642-650. 

Epigenetic mechanisms that negatively regulate the expression of SDF or CXCR4 may be necessary for tumor metastasis. One example is DNA methyla-tion, a modification typically associated with inactivation of tumor suppressors, and it has been shown that methylation of the SDF promoter in colonic epithelium promotes metastasis of these tumors [60, 61]. Also, the CXCR4 promoter was found to be regulated by DNA methylation in pancreatic cancer, which shows decreasing mRNA and protein levels [62]. 

With the aid of monoclonal antibodies, sialylated carbohydrate structures, notably sialyl Lea and sialyl Lex, were discovered to function as receptors for the selectins [43]. Sialyl Lex is usually located on leukocytes, but also highly expressed on a variety of different cancer cells [45]. The same holds true for sialyl Lea, which serves as a tumor marker on gastrointestinal and pancreatic cancers [46]. Owing to the function of sialyl Lewis structures in the extravasation of cancer cells from the bloodstream and promoting metastatic spread to other tissues, a clear correlation of expression of sialyl Lea and sialyl Lex on tumors with enhanced progression and metastasis was observed. Since it is assumed that these tumor-associated carbohydrate markers enhance extravasation and metastasis by interactions with selectins, experiments were performed where selectin expression was inhibited. Long-term studies showed that cancer... 

Intraoperative molecular detection of circulating tumor cells by reverse transcription-polymerase chain reaction in patients with bihary-pancreatic cancer is associated with hematogenous metastasis. Ann Surg Oncol, 9, 364—370. 

Scaife C L, Shea J E, Dai Q, Firpo M A, Prestwich G D and Mulvihill S J (2008), Synthetic extracellular matrix enhances tumor growth and metastasis in an orthotopic mouse model of pancreatic adenocarcinoma , J Gastrointest Surg, 12, 1074-80. 

Histologically, islet tumors are formed from chords of islet cells. The benign tumors are well encapsulated. The appearance of the individual cells in the malignant tumor is not very different from that in the benign tumor, but there is no fibrous capsule in the former. In contrast, surrounding tissues are invaded, and metastasis may develop. Occasionally, benign or malignant tumors of the islet cells may appear in ectopic pancreatic formation. 

---