The Clinicopathological Characteristics And Prognosis Of Gastrointestinal Stromal Tumors Arose From Rare Locations

Background Gastrointestinal stromal tumor(GIST)is the most common mesenchymal tumor in human alimentary tract.GIST most occurs in stomach(50-60%),followed by small intestine(30-35%),colorectum(5%),esophagus(<1%)and other special locations such as omentum,mesentery,and retroperitoneum.Tumor location is a well documented independent prognostic factor for GIST.The modified National Institutes of Health(NIH)risk category distinguished GIST from “gastric” and “non-gastric”,and a series of special locations were not discussed in this system,which could lead to a bias to the recurrence risk prediction.Due to the rare incidence of this subgroup of GIST,the related research was lacking.The current study collected and analyzed the clinicopathological features and prognosis of hepatic GIST,pancreatic GIST,duodenal GIST and gastric GIST with synchronous gastric cancer,which might provide new evidence for accurately predicting the recurrence risk of GIST.Part Ⅰ Hepatic GISTObjective To evaluate the clinicopathological features and prognosis of primary hepatic GIST in order to achieve the optimal treatment strategy.Patients and Methods One case of primary hepatic GIST from our center and 22 cases reported in MEDLINE or China National Knowledge Infrastructure(CNKI)were enrolled into this study.Clinicopathological features as well as survival data of hepatic GIST were analyzed and compared with 297 gastric GISTs from our center.Results Majority of the 22 cases(95.7%)of hepatic GIST was larger than 5 cm in size,and 75.0% of the tumors were over 5/50 HPF in mitotic index.Most of the hepatic GISTs(85.7%)displayed spindle cell shape in morphology.All of the hepatic GIST(100%)enrolled in this study were classified as high-risk category by the NIH risk classification.The 5-year median DFS time was 24.0 months and 5-year DSS rate was 33.3%,respectively.Distribution of clinicopathological features was significantly different between hepatic and gastric GIST.The DFS and DSS of hepatic GIST were significantly lower than those of gastric GIST.Conclusion Majority of the hepatic GIST is large in size and highly malignant.Prognosis of the primary hepatic GIST is worse than that of gastric GIST.Part Ⅱ Pancreatic GISTObjective To investigate the clinicopathological features and prognosis of primary pancreatic GIST.Patients and Methods One case of pancreatic GIST from our center and 44 cases reported in MEDLINE were enrolled in this study.Clinicopathological features and prognosis of pancreatic GISTs were analyzed and compared with 297 gastric GISTs from our center.Results The most common location was head of pancreas(38.5%).The majority of pancreatic GISTs exceeded 5 cm(74.4%),displayed cystic or mixed imaging features(56.4%),and were high risk(85.7%).The 5-year DFS and DSS rates were 66.1% and 95.8%,respectively.Mitotic index was the only risk factor for DFS of pancreatic GISTs.The distribution of tumor size,histologic type and NIH risk category were significantly different between pancreatic and gastric GISTs.The 5-year DFS rate of pancreatic GISTs was significantly lower than that of gastric GISTs.Conclusion The most common location was head of pancreas.The majority of pancreatic GISTs were large and highly malignant.Pancreatic GISTs differed significantly from gastric GISTs in respect to clinicopathological features.The DFS of pancreatic GISTs was worse than that of gastric GISTs.Part Ⅲ Duodenal GISTObjective To explore the optimal surgical strategy and prognosis of duodenal GIST.Patients and Methods A total of 301 cases of duodenal GISTs were obtained from our center(37)and from case reports or series(264 cases)extracted from MEDLINE.Clinicopathological features,type of resection and survivals duodenal GISTs were analyzed.Results The most common location was descending portion(138/267,51.7%)and the most common symptom was bleeding(128/301,42.5%).The median tumor size was 4 cm.Most patients(66.4%)received limited resection(LR).Pancreaticoduodenectomy(PD)was mainly performed for GISTs with larger tumor size or arose from descending portion(both P<0.05).For both the entire cohort and tumors located in the descending portion,PD was not an independent risk factor for DFS and DSS(both P>0.05).Duodenal GISTs were significantly different from gastric GISTs with respect to tumor size,mitotic index and NIH risk category(all P<0.05).The DFS and DSS of duodenal GISTs was significantly worse than that of gastric GISTs(both P<0.05).Conclusion LR was more prevalence and PD was mainly performed for tumors with larger diameter or located in descending portion.Type of resection was not an independent risk factor for the prognosis of duodenal GISTs.Prognosis of duodenal GISTs was significantly worse than that of gastric GISTs.Part Ⅳ Coexistence of gastric GIST and gastric cancerObjective To explore the clinicopathological features and prognosis of gastric GIST patients with synchronous gastric cancer.Patients and Methods From May 2010 to November 2015,a total of 241 gastric GIST patients were retrospectively enrolled in current study.The clinicopathological features and prognosis of gastric GIST patients with synchronous gastric cancer were analyzed and compared with the single primary gastric GIST.Results Among the 241 patients,24 patients had synchronous gastric cancer(synchronous group)and 217 patients did not(no-synchronous group).The synchronous group presented a higher percentage of elders(66.7% vs 39.6%,P=0.001)and males(87.5% vs 48.4%,P<0.001)than the no-synchronous group.The tumor diameter,mitotic index and NIH category were also significantly different between the two groups(all P<0.05).The 5-year DFS(54.9% vs 93.5%,P<0.001)and overall survival(OS)(37.9% vs 89.9 %,P<0.001)rates of synchronous group were significantly lower than those of no-synchronous group.However,the 5-year OS between synchronous group and gastric cancer group were comparable(37.9% vs 57.6%,P=0.474).Conclusion The coexistence of gastric GIST and gastric cancer is common in elder male patients.The synchronous GIST is commonly in low risk category.The prognosis of gastric GIST with synchronous gastric cancer is worse than that of primary-single gastric GIST,but is comparable with primary-single gastric cancer.