5-year survival rate lower in pancreatic vs gastric gastrointestinal stromal tumours
The head of pancreas is the most common location of pancreatic gastrointestinal stromal tumour (GIST), which is usually large and highly malignant, according to a study. Pancreatic GISTs significantly differ from gastric GISTs in terms of clinicopathologic features. In addition, disease-free survival (DFS) is worse in pancreatic GISTs than in gastric GISTs.
“The majority of pancreatic GISTs exceeded 5 cm in diameter, displayed cystic or mixed imaging features, and were high risk. The imaging features were correlated with tumour size and histologic type,” researchers said.
“Mitotic index was the only risk factor for DFS of pancreatic GISTs,” they added.
The investigators enrolled one case of pancreatic GIST from their centre and 44 cases reported in Medline. They analysed and compared clinicopathologic features and prognosis of pancreatic GISTs with 297 gastric GISTs.
Overall, 38.5 percent of pancreatic GISTs were situated at the head of pancreas. Most of these tumours (74.4 percent) went beyond 5 cm, showed cystic or mixed imaging features (56.4 percent), and were high risk (85.7 percent). [J Clin Gastroenterol 2017;51:850–856]
The 5-year DFS rate was 66.1 percent and disease-specific survival rate 95.8 percent. The only risk factor for DFS of pancreatic GISTs was mitotic index.
There was a significant difference between pancreatic and gastric GISTs in the distribution of tumour size, histologic type and National Institutes of Health risk category. Furthermore, the 5-year DFS rate of pancreatic GISTs was significantly lower compared with that of gastric GISTs. Location was an independent prognostic factor for DFS between the two GISTs based on multivariate analysis.
“In our present study, 14 tumors displayed cystic mass (35.9 percent) and eight tumours showed mixed mass (20.5 percent),” researchers said.
The investigators further explained that cystic lesions of the pancreas are mostly “pseudocysts, related to chronic pancreatitis.”
“Cystic tumors of the pancreas most commonly correspond to serous microcystic adenoma, mucinous cystic tumor, intraductal mucinous tumor, and solid pseudopapillary tumor, while less commonly to cystic endocrine tumors, cystic teratomas, cystic metastasis, and lymphagiomas,” they added. [Cases J 2009;2:9138]
GISTs rarely occur in the pancreas, but they should be considered in the differential diagnosis of cystic pancreatic masses, according to researchers, adding that it is difficult to have a correct diagnosis of cystic pancreatic GISTs prior to operation.
This study is limited by its retrospective design, which restricts the completeness of data, and the small sample size of pancreatic GISTs, which will lead to sampling error. In addition, researchers could not compare the clinicopathologic features and prognosis of pancreatic and nongastric GISTs due to the limited sample size of duodenal, small intestinal and rectal GISTs in their centre.
“GIST is the most common mesenchymal neoplasm of the alimentary tract and represents 1 to 2 percent of all gastrointestinal malignant tumors. GIST is considered to arise from the interstitial cells of Cajal, the pacemaker cells of the alimentary tract,” according to researchers. [Surg Clin North Am 2011;91:1079–1087; World J Surg Oncol 2013;11:273]