Gastrointestinal stromal tumors: current diagnosis, biologic behavior, and management

Colorectal gastrointestinal stromal tumor

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm arising in the digestive tract, with an estimated prevalence of 15-20 per 1,000,000. GISTs are related to the interstitial cells of Cajal and are characterized by constitutive over-expression of the transmembrane tyrosine kinase receptor KIT. This is produced by a patognomonic mutation of the proto-oncogene c-kit that occurs in up to 90% of cases. Exon 11 is affected most frequently; exons 9 and 13 are less commonly involved. One-third of GISTs lacking KIT mutations exhibits alternative activating mutations in the PDGFRα gene. Colorectal GISTs represent about 5-10% of the cases, mainly located in the rectum that is the third common site. Benign GISTs are more common, but many tumors are of uncertain malignant potential; tumor size and rate of mitosis are still the most reliable criteria for assessing the risk of an aggressive behavior. Surgery is the first-line treatment for resectable non-metastatic colorectal GIST. Standard oncologic resection is inappropriate because skip metastases and lymphatic spread are rarely reported. Segmental colectomy with negative margins is recommended, and local excision is oncologically adequate in highly selected rectal tumors. Radical surgery alone is not always curative especially in high-risk GISTs, and half of patients develops local recurrences or distant metastases after R0 operation. Medical therapeutic strategies have rapidly evolved after the introduction of targeted molecular therapy. Efficacy and safety of imatinib mesylate was first demonstrated in patients with metastatic and unresectable disease. Adjuvant and neoadjuvant use of imatinib are promising therapeutic options to improve the outcome of surgery to downstage unresectable lesions and to allow less extensive resections.

[Successful resection of locally advanced gastrointestinal stromal tumor of the ampulla of Vater after treatment with imatinib]

Gastrointestinal stromal tumor (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract arising from Cajal's cells, expressing CD 117. The standard treatment for primary GIST is complete surgical resection. Imatinib mesylate, a specific tyrosine kinase inhibitor, is effective against locally advanced and metastatic GIST. There are several reports of the effect of preoperative imatinib in patients with unresectable and locally advanced primary GIST. We report a case of unresectable primary GIST of the ampulla of Vater, which we were able to completely resect after treatment with a dosage of imatinib 400 mg daily for 5 months. Twelve months later, the patient was treated with imatinib and doing well with no evidence of recurrence.

Clinicopathological and immunohistochemical features of gastointestinal stromal tumors

PURPOSE

The purpose of this study was to evaluate the clinicopathological features and immunohistochemical features of gastrointestinal stromal tumor (GIST), and specifically the expressions of platelet derived growth factor receptor A (PDGFRA), protein kinase C theta (PKC theta), discovered on GIST-1 (DOG-1), p16 and p27.

MATERIALS AND METHODS

Total 118 patients who underwent surgical resection for GIST at our institution between Jan 1997 and Dec 2007 were retrospectively studied. Immunohistochemical staining for c-kit, PDGFRA, PKC-theta, DOG-1, p16 and p27 was performed on a tissue microarray of the 118 GIST. The clinicopathologic parameters, the disease-free survival (DFS) and the overall survival rate were analyzed along with immunohistochemistry.

RESULTS

The immunohistochemical stains for c-kit, CD34, PKC-theta, PDGFRA, DOG-1, p16 and p27 were positive in 89.8%, 72.0%, 56.8%, 94.9%, 90.7%, 69.5% and 44.1% of the tumor samples, respectively. The immunohistochemical expression of c-kit was strongly correlated with PKC-theta (p=0.000), DOG-1 (p=0.000) and CD34 (p=0.002). The DFS rate was significantly decreased for the patients with peritoneal GIST, high risk GIST, ≥10 cm-sized GIST, ≥10 mitoses/50 high power fields (HPFs) and p16 positivity (p=0.001, p=0.004, p=0.001, p=0.003 and p=0.028). GISTs ≥10 cm, epithelioid tumor cell type, and c-kit, and DOG-1 negativity were significantly associated with shorter period of overall survival (p=0.048, p=0.006, p=0.000 and p=0.000).

CONCLUSION

The expression of p16 and no expression of c-kit and DOG-1 in GISTs, as well as peritoneal tumor site, high risk group, large tumor size, epithelioid tumor cell type and numerous mitoses, may be potentially prognostic factors for predicting worse outcome for patients who suffer from GIST.

Diagnosis of subepithelial tumors in the upper gastrointestinal tract by endoscopic ultrasonography

Endoscopic ultrasonography (EUS) is the most accurate procedure for detecting and diagnosing subepithelial tumors, due to its higher sensitivity and specificity than other imaging modalities. EUS can characterize lesions by providing information on echogenic origin, size, borders, homogeneity, and the presence of echogenic or anechoic foci. Linear echoendoscopes, and recently also electronic radial echoendoscopes, can be used with color Doppler or power Doppler to assess the vascular signals from subepithelial masses, and thus permit the differentiation of vascular structures from cysts, as well as the assessment of the tumor blood supply. However, the diagnostic accuracy of EUS imaging alone has been shown to be low in subepithelial lesions with 3rd and 4th layers. It is also difficult to differentiate exactly between benign and malignant tumors and to gain an accurate picture of histology using EUS. On the other hands, EUS guided fine needle aspiration (EUS-FNA) can provide samples for cytologic or histologic analysis. Hypoechoic lesions of the 3rd and the 4th EUS layers, more than in 1 cm diameter are recommended, and histologic confirmation using endoscopic submucosal resection or EUS-FNA should be obtained when possible. Therefore, EUS-FNA plays an important role in the clinical management of subepithelial tumors. Furthermore improvements in endoscopic technology are expected to be more useful modalities in differential diagnosis and discrimination between benign and malignant subepithelial tumors.

Colorectal gastrointestinal stromal tumors: a brief review

Gastrointestinal stromal tumors (GISTs) are rare lesions that constitute the majority of mesenchymal tumors in the gastrointestinal tract. Within the colon and rectum, they represent 0.1% of all cancers. They can present with a variety of symptoms but are often asymptomatic. Although many lesions may be benign, up to half of patients develop recurrent disease within a few years. Almost all GISTs contain a mutation in the c-kit tyrosine kinase that leads to its constitutive activation and results in cell proliferation. This discovery has led to the immunostaining of the c-kit antigen (CD117) to distinguish GISTs from other malignancies. Radiologic examinations can be helpful in initial diagnosis and staging. Surgery is the best treatment for cure, but recent advances have led to the use of imatinib mesylate, a tyrosine kinase inhibitor, to treat metastatic or unresectable disease, or both. There are currently many clinical trials available to help treat GISTs.

Abdominal wound metastasis after laparoscopic surgery of gastrointestinal stromal tumor

Surgical resection is the mainstay treatment for gastrointestinal stromal tumors (GISTs). Laparoscopic surgery can be considered for treating these tumors since their biologic behavior lends them to curative resection without requiring large margins or extensive lymphadenectomy. Despite complete resection, GISTs frequently recur specifically in the liver and peritoneum. Although they occur in other upper gastrointestinal malignancies, recurrences of GISTs at the port sites after laparoscopic surgery have rarely been reported. We describe here a patient with abdominal wound metastasis after laparoscopic surgery for GIST.

[Controversies in the surgical treatment of primary gastrointestinal stromal tumours (GIST)]

It is estimated that 50% of GIST are located at the time of their diagnosis. A complete surgical resection can be performed in up to 95% of these cases, making this the most important prognostic factor. This surgery must fulfil a series of technical requirements so as to be really effective, as it has to be R0, with no tumour rupture, with preservation of the pseudo-capsule, etc. Although the majority of GIST are gastric, their location in other anatomical areas, such as the oesophagus, duodenum or rectum, require the surgeon to use more complex techniques. Laparoscopy is increasingly used; however, we must avoid its use, due to there being few experienced groups or if there are large tumours. The use of neoadjuvant therapy has revived great interest by allowing to resection tumours that were once non-resectable or in very compromised anatomical locations, with less aggressive surgery. The use of pre-surgical biopsy is not exempt from serious risks, thus it should only be used for establishing a neoadjuvant treatment or if there are diagnostic doubts with other diseases in high risk patients.

Imatinib as the first and only treatment in Europe for adult patients at significant risk of relapse following gastrointestinal stromal tumor removal

Mutations of the KIT gene are the molecular hallmark of most gastrointestinal stromal tumors (GISTs). GIST has become a model for targeted treatment of solid tumors, imatinib becoming the standard first-line treatment of these tumors in the advanced/metastatic phase. Because of the efficacy of imatinib treatment in the advanced setting, its role following resection of a primary non-metastatic GIST was investigated. The recently published phase III, double-blind, placebo-controlled, multicenter ACOSOG Z9001 study showed that adjuvant therapy is safe, and significantly improves recurrence-free survival compared to placebo when given after resection. To what extent imatinib will improve overall survival has yet to be answered. What is clear is that high-risk GIST patients definitely need adjuvant therapy, and that 1 year of imatinib is not enough for the patients who do need it. The questions of optimal duration of imatinib treatment in the adjuvant setting, adequate selection of risk patients and effect of imatinib on overall survival are currently being studied.

Synchronous gastrointestinal stromal tumors (GIST) and other primary cancers: case series of a single institution experience

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal neoplasm affecting the gastrointestinal tract. The incidental occurrence of mesenchymal tumors and other primary tumors has not been well described in literature.

OBJECTIVE

The aim of this study was to evaluate the clinical and pathologic features of GIST occurring synchronously with other primary tumors.

METHODS

Forty-three patients with diagnosis of GIST treated surgically with curative intent at our institution from 1998 to 2006 were included. The patient clinical data and pathological reports were reviewed.

RESULTS

Of the 43 patients, there were 6 (14%) cases of synchronous GIST and other primary tumors discovered as coincidental findings. The synchronous GISTs analyzed were located in the stomach (50%) and small intestine (50%), size ranging from 0.7 to 7.6 cm (median 3.35 cm). Five (83%) of the concurrent primary tumors were from gastrointestinal origin and only one (17%) patient presented with concurrent breast cancer and GIST. The synchronous GISTs immunofenotype shows positivity for CD117 and CD34 (100%), smooth-muscle actin (SMA) (67%), S100 (50%) and desmin (33%). Whereas staining for cytokeratin AE1/AE3 and PDGF were all negative. According to GIST risk category for aggressive behavior three were classified as very low, one intermediate and two high.

CONCLUSIONS

The synchronous occurrence of GISTs and other primary neoplasm is not an uncommon entity and usually they are discovery incidentally. Epithelial tumors of the gastrointestinal tract are the most associated with concomitant GISTs. Further studies are required to clarify the molecular and genetic mechanisms of carcinogenesis and progression associating GIST and synchronous tumors.

Outcome after curative resection of large (>or=10 cm) gastric gastrointestinal stromal tumors: how frequent is adjacent organ involvement and is concomitant distal pancreatectomy necessary?

INTRODUCTION

Complete tumor resection with clear margins including adjacent organs is the treatment of choice for gastrointestinal stromal tumors (GISTs). However, true tumor invasion of adjacent organs has been reported to be rare. Concomitant distal pancreatectomy (DP) for suspected tumor infiltration is not infrequently performed during resection of large gastric GISTs. This study aims to determine the true frequency of adjacent organ involvement by large gastric GISTs with particular attention to the pancreas and compares the outcome after curative resection with and without a concomitant DP in order to determine if DP is truly necessary.

METHODS

A retrospective review of 37 patients who underwent curative resection of large (>or=10 cm) gastric GISTs was conducted.

RESULTS

Wedge resections were performed in 22, partial gastectomies in nine, and total gastrectomies in six patients. The median operative time was 180 min (range, 60-330 min), and the patients had a median postoperative stay of 8 days (range, 4-29 days). Overall, there were eight (22%) morbidities including two (5%) mortalities. Nineteen (51%) had concomitant adjacent organ resection, and these included 15 (41%) DPs with splenectomies. Direct organ invasion was demonstrated in 5/19 patients (26%) and 7/30 organs (23%) resected. Only 1/15 (6.7%) DP specimens demonstrated tumor infiltration. Comparison between the patients with and without a concomitant DP demonstrated that performance of a DP was associated with a longer operation time [225 min (range, 105-305 min) vs 158 min (60-330 min), P=.002)], increased postoperative stay [9 days (range, 7-29 days) vs 7.5 days (4-19 days), P=.042], and increased postoperative morbidity [6 (40%) vs 2 (9%), P=.025]. The DP cohort also had a statistically significant poorer 5-year recurrence free survival (22% vs 60%, P=.017).

CONCLUSION

Although adjacent organ involvement is not uncommon with large gastric GISTs, concomitant DP is usually unnecessary as direct pancreatic invasion is rare. Furthermore, concomitant DP with splenectomy is associated with an increase in postoperative morbidity.

Gastric glomus tumor: a case report

Gastric glomus tumors are rare mesenchymal tumors of the gastrointestinal tract. We describe a 72-year-old patient who presented with episodes of melena and was subsequently investigated for a tumor of the antrum of the stomach. Surgical resection revealed a 2 x 2 x 1.7 cm well circumscribed submucosal tumor, extending into the muscularis propria. The histopathologic examination of the specimen demonstrated a glomus tumor of the stomach. We discuss the preoperative investigation, the diagnostic problems and the surgical treatment of the patient with this rare submucosal lesion.

Gastrointestinal Stromal Tumor of the Stomach with Narrow Stalk-Like Based, Uneven Protruding Appearance Presenting with Severe Acute Anemia despite Small Size

We report the case of a 56-year-old woman who had a gastrointestinal stromal tumor (GIST) of the stomach. She was admitted to our hospital for epigastric pain, nausea, and severe acute anemia (hemoglobin level 4.3 g/dl). Esophagogastroduodenoscopy revealed a narrow stalk-like based, hemorrhagic and uneven protruding lesion in the lesser curvature of the gastric upper corpus. Although the tumor was less than 2 cm in diameter and was probably a benign GIST according to histology, laparoscopy-assisted local resection was needed because the patient had continuous severe anemia and epigastric pain. Histological assessment showed that the elongated spindle-like tumor cells originated from the intrinsic muscle layer, and was shown with growth to the mucosal side, cropping out to the surface in most areas of the protruding lesion. Only a small part of the tumor was within nontumoral gastric mucosa. Most of the tumor cells demonstrated immunoreactivity for KIT and CD34 in the cytoplasm but not for αSMA, S100, and desmin. Mitotic activity (0/50 high power field) and the labeling index for MIB-1 (about 1%) were low. The GIST of the stomach described in this report was a rare case with a narrow stalk-like based, uneven protruding mass presenting with severe acute anemia despite small size.

Gastrointestinal stromal tumours: a clinico-radiologic review from a single centre in South India

Gastrointestinal stromal tumours (GISTs) are rare tumours but are the commonest mesenchymal neoplasms in the gastrointestinal tract. To our knowledge, there is no large case series in Asian countries in which a clinico-radiological descriptive analysis of these tumours has been carried out. In this retrospective study, we analysed our experience of 70 patients with histopathologically proven GISTs, who were presurgically investigated by using CT, and describe the demography, anatomical distribution, imaging features and clinical course of the GIST. We found an unusually large predominance of males in our study, stomach and small bowel appeared to have been involved similarly and small bowel tumours had a higher rate of metastases. We also highlight some unusual CT features of these tumours that we encountered during the study, such as the presence of metastatic lymphadenopathy and satellite nodules, relapse in appendices epiploicae of the bowel, metachronous liposarcoma, adrenal and lung metastases, multiplicity of lesions and aneurysmal dilatation of the bowel. Two of our patients also had multiple neurofibromas, whose association with GIST has been seen in earlier reports. To the best of our knowledge, this article presents one of the largest series of articles on GISTs, to date, in Asian countries. We conclude with a differential diagnosis of GIST, with salient features distinguishing each entity.

Large gastrointestinal stromal tumor size does not imply early recurrence

A 28-year-old female presented with a huge intra-abdominal mass. Initially a mesenteric mass was diagnosed, but her tumor was found to be a gastrointestinal stromal tumor (GIST). Laparotomy was performed. The mass was resected en bloc with clear surgical margins in January 2007. It was found to be 20 × 18 × 16 cm. In order to remove the tumor, the left half of transverse colon with its mesocolon, spleen, body and tail of pancreas, and a part of the small intestine had to be removed. The mass was tightly attached to these viscera. The tumor was surgically removed three years ago. The pathology report of the case presented places the tumor in the high-risk category. The tumor had a relatively high mitotic index. It was positive for CD117 and CD34 stains and also positive for smooth muscle actin. Although the patient did not receive adjuvant chemotherapy, no signs of local recurrence or distant metastasis could be recognized on follow up. Surgery remains the standard initial management for all localized GISTs. The tumor should be removed en bloc, with clear surgical margin. The case presented indicates no association of tumor size with early local recurrence of the tumor or early distant metastasis.

A Band Lifting Assisted Method for Laparoscopic Resection of Gastrointestinal Stromal Tumors on the Posterior Wall of the Stomach

Laparoscopic surgical techniques are beneficial for the wedge resection of gastrointestinal stromal tumors (GISTs). We have developed a new technique of laparoscopic transgastric resection for GISTs of the posterior wall of the stomach, a band lifting wedge resection method that has been confirmed to ensure sufficient surgical margins around the resected specimen in 21 cases. GISTs located at the posterior wall of the stomach were collected for this study. Laparoscopic anterior gastrotomy was performed and a 9-Fr rubber band was looped around the base of the tumor, allowing it to be lifted up through the anterior gastrotomy. The lesion was transected using a laparoscopic linear cutter and the gastrotomy was then closed by sequential application of the linear cutter. Surgical specimens were examined immunohistochemically All GISTs were successfully and completely resected using the laparoscopic technique. The resected tumors were ellipse-shaped or round. Macroscopic examination of the resected specimens showed complete tumor excision with negative surgical margins in all patients. A band lifting method for transection of GISTs on the posterior wall of the stomach easily allows for sufficient surgical margins of GISTs. The technique is reliable and feasible for laparoscopic treatment of GISTs in the stomach.

Stromal duodenal tumor revealed by an acute pancreatitis: report of a case

INTRODUCTION

Gastrointestinal stromal tumors (GISTs) are one of the most common mesenchymal neoplasms of the human gastrointestinal tract. Duodenal GISTs are very rare and constitute less than 5% of all kind of GISTs.

CASE REPORT

This is a report of a rare gastrointestinal stromal tumor of the duodenum in a 25-year-old female who was presented as an acute pancreatitis.

DISCUSSION

The computed tomography evoked a pancreatic tumor. The patient underwent successful Whipple's procedure. The histological and immunohistochemical exams of the specimen resection confirmed the diagnosis of duodenal stromal tumor.

Surgery for gastrointestinal stromal tumors of the duodenum

BACKGROUND

Duodenal gastrointestinal stromal tumors (GISTs) represent a unique dilemma with varied surgical treatment options. However, the impact of operative methods on disease recurrence has never been addressed.

METHODS

We retrospectively reviewed the medical records of all patients with duodenal GISTs treated at our hospital from January 2001 to December 2008.

RESULTS

Of the 25 patients included for analysis, 9 had pancreaticoduodenectomy (PD) and 16 had limited operation. Comparison of clinicopathological data between tumors treated by PD and by limited operation showed no significant differences in patient age, sex, symptoms, location of tumor, tumor grade, immunohistochemical staining pattern, or complications after surgery. However, patients with tumors >5 cm (P = 0.005) or not diagnosed as GISTs before surgery (P = 0.004) were significantly more frequently treated by PD. In multivariable analysis, the only significant predictor for disease recurrence was high-risk duodenal GISTs.

CONCLUSIONS

Based on the fact that type of operation was not correlated to operative risk and disease recurrence, limited operation rather than PD should be attempted for duodenal GIST without involvement of papilla of Vater to preserve more pancreas parenchyma, duodenum, and common bile duct.

Is it possible to differentiate gastric GISTs from gastric leiomyomas by EUS?

AIM: To evaluate the ultrasonography (EUS) features of gastric gastrointestinal stromal tumors (GISTs) as compared with gastric leiomyomas and then to determine the EUS features that could predict malignant GISTs.

METHODS: We evaluated the endoscopic EUS features in 53 patients with gastric mesenchymal tumors confirmed by histopathologic diagnosis. The GISTs were classified into benign and malignant groups according to the histological risk classification.

RESULTS: Immunohistochemical analyses demonstrated 7 leiomyomas and 46 GISTs. Inhomogenicity, hyperechogenic spots, a marginal halo and higher echogenicity as compared with the surrounding muscle layer appeared more frequently in the GISTs than in the leiomyomas (P < 0.05). The presence of at least two of these four features had a sensitivity of 89.1% and a specificity of 85.7% for predicting GISTs. Except for tumor size and irregularity of the border, most of the EUS features were not helpful for predicting the malignant potential of GISTs. On multivariate analysis, only the maximal diameter of the GISTs was an independent predictor. The optimal size for predicting malignant GISTs was 35 mm. The sensitivity and specificity using this value were 92.3% and 78.8%, respectively.

CONCLUSION: EUS may help to differentiate gastric GISTs from gastric leiomyomas. Once GISTs are suspected, surgery should be considered if the size is greater than 3.5 cm.

Gastrointestinal stromal tumors–a review

Gastrointestinal stromal tumors (GISTs) may be defined as intraabdominal nonepithelial (mesenchymal) tumors that express the KIT protein or have an activating mutation in a class III receptor tyrosine kinase gene (KIT or PDGFRA). GISTs are diagnosed at a frequency of about 15 new cases annually per million, though small indolent GISTs are likely to occur more frequently in the general population. The clinical behavior is variable, and assessment of the malignancy potential is usually based mainly on the size and the proliferation characteristics of the tumor. The overwhelming majority of GISTs express the KIT protein, the transmembrane receptor tyrosine kinase for the stem cell factor. The majority of GISTs harbor a mutation in the KIT proto-oncogene that translates into constitutively activated KIT protein kinase, and a minority have mutated PDGFRA gene resulting in activated platelet-derived growth factor alpha receptor tyrosine kinase. Most GISTs respond to imatinib mesylate, which selectively inhibits both KIT and PDGFRA, and is now considered as the standard systemic therapy for advanced GIST. In contrast, responses to conventional chemotherapy are infrequent (generally less than 10%), but combination therapies with imatinib have not been explored. Research on adjuvant imatinib and novel targeted therapies is ongoing.

Double-balloon enteroscopy and small bowel tumors: a South-European single-center experience

Small bowel tumors are rare, accounting for 1-2% of all gastrointestinal neoplasms. We sought to determine the diagnostic and therapeutic impact of double-balloon enteroscopy (DBE) in patients with small bowel tumors. Between January 2005 and March 2008, 78 patients underwent 96 DBE. All nine patients (seven males; mean age 68 +/- 11.3 years) with small bowel tumors were retrospectively reviewed. Clinical presentation was: mid-gastrointestinal bleeding or iron-deficient anemia (55.6%); abdominal pain (22.2%); nausea/vomiting and abdominal distension (22.2%). Five patients had abnormal findings in previous capsule endoscopy and four in previous radiologic examinations. Route of insertion was exclusively oral and abnormal lesions were detected in all patients (jejunum 8; ileum 1). Biopsies were taken in seven patients and provided definitive histological diagnosis in all except one. There were no complications of DBE. Surgical resection took place in eight patients. Final histologic diagnosis were: primary carcinoma (33.3%), gastrointestinal stromal tumor (GIST) (33.3%), malignant lymphoma (22.2%), and carcinoid tumor (11.1%). Mean follow-up time was 15.4 +/- 12.7 months (range 2-34 months). Six patients were submitted to chemotherapy. Two patients died. Small bowel tumors are common in patients submitted to DBE. Given its safety and diagnostic capabilities, DBE should be considered the gold-standard method in the study of these neoplasms.

Surgery for gastrointestinal stromal tumors of the stomach

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are the main mesenchymal neoplasms in the gastrointestinal tract. Tumor size, mitotic rate, and location correlate with potential malignancy and recurrence rate. Results of surgical treatment of gastric GIST are analyzed with emphasis on recurrence of disease after intermediate follow-up.

METHODS

From 1998 to 2006, a total of 63 patients (median age 62.1 +/- 14.1) underwent gastric resection for GIST. Fifty-five patients (93.6%) returned for follow-up investigations, which included computed tomography in 45, gastroscopy in 32, and endosonography in 29. Positron emission tomography was done in five patients.

RESULTS

Mean tumor size was 5.3 +/- 3.8 cm. Open atypical gastric resection was done in 32, distal gastric resection in five, and remnant gastrectomy in four patients. Laparoscopic gastric resection was initiated in 22 patients; the conversion rate was four of 22 (18.2%). Overall, R0 resection was reached in 61/63 patients (96.8%). According to the Fletcher criteria, 33 tumors (52.4%) were classified as intermediate or high risk GIST. Six patients (9.5%) died of unrelated causes before follow-up. After a median follow-up of 2.5 years, overall recurrence rate was 7.0% after R0 resection.

CONCLUSION

Histologically proven complete resection is an effective treatment for gastric GIST. Laparoscopic procedures were carried out successfully in selected patients.

Does imatinib turn recurrent and/or metastasized gastrointestinal stromal tumors into a chronic disease? - single center experience

BACKGROUND

Gastrointestinal stromal tumors (GIST) are mesenchymal tumors of the gastrointestinal tract supposed to arise from the cells of Cajal because of gain-of-function mutations of the tyrosine receptor kinases c-kit or platelet-derived growth factor receptor A. Imatinib selectively inhibits the kinase activity of both receptors. Despite this breakthrough in the treatment of GIST, resistance against imatinib has been reported to be as high as 50% after the first 2 years of treatment.

AIM

Outcome of 13 consecutive patients with relapsed or metastasized GIST who were treated with imatinib was analyzed.

RESULTS

Mean duration of treatment was 53.5 months. Four patients developed progressive disease and died after a mean treatment time of 31 months in spite of increase of imatinib dosages to 800 mg daily. Two patients (23%) developed a progressive disease after 46 months or 52 months of treatment. Two patients had a stable disease and five had a partial response. The overall progression rate was 46%, the mean survival time since primary diagnosis was 85.8 months.

CONCLUSION

From our experience, frequency of resistance development to imatinib may be below that given in the literature (50% after 2 years). Individual treatment in specialized centers may improve compliance.

Laparoscopic sleeve gastrectomy in the treatment of gastrointestinal stroma tumours in morbid obese patients

We saw two cases of gastrointestinal stroma tumour (GIST) in morbid obese patients 6 months ago. They were diagnosed with endoscopic ultrasonography. We used laparoscopic sleeve gastrectomy (LSG), a new bariatric surgery, in order to treat morbid obesity and GISTs at the same time. After the operation, the GISTs were removed successfully. The body weights and fasting glucose levels decreased significantly. As a result, LSG is a good and simple method in treating GISTs in morbid obese patients.

Surgery for gastrointestinal stromal tumors of the stomach

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are the main mesenchymal neoplasms in the gastrointestinal tract. Tumor size, mitotic rate, and location correlate with potential malignancy and recurrence rate. Results of surgical treatment of gastric GIST are analyzed with emphasis on recurrence of disease after intermediate follow-up.

METHODS

From 1998 to 2006, a total of 63 patients (median age 62.1 +/- 14.1) underwent gastric resection for GIST. Fifty-five patients (93.6%) returned for follow-up investigations, which included computed tomography in 45, gastroscopy in 32, and endosonography in 29. Positron emission tomography was done in five patients.

RESULTS

Mean tumor size was 5.3 +/- 3.8 cm. Open atypical gastric resection was done in 32, distal gastric resection in five, and remnant gastrectomy in four patients. Laparoscopic gastric resection was initiated in 22 patients; the conversion rate was four of 22 (18.2%). Overall, R0 resection was reached in 61/63 patients (96.8%). According to the Fletcher criteria, 33 tumors (52.4%) were classified as intermediate or high risk GIST. Six patients (9.5%) died of unrelated causes before follow-up. After a median follow-up of 2.5 years, overall recurrence rate was 7.0% after R0 resection.

CONCLUSION

Histologically proven complete resection is an effective treatment for gastric GIST. Laparoscopic procedures were carried out successfully in selected patients.

Gastrointestinal stromal tumour--evolving concepts

INTRODUCTION

GISTs are rare tumours ofthe gastrointestinal tract constituting less than 1% of all primary neoplasms. They remain the commonest mesenchymal tumours of the gut. Historically they have been confused with more common tumours of smooth muscle and neurogenic origin because they share their histological features. Only in the past two decades has the identification of immunohistochemistry marker CD 117 (c-kit) greatly enhanced their diagnosis. Considerable perplexity surrounds prediction of their malignant potential because the predictive factors used can only make an approximate measurement of their behaviour.

METHODS

Medline Pubmed and Cochrane database searches were performed and the articles found were cross referenced.

CONCLUSION

GIST has an estimated annual incidence of 12-14 per million population. Stratifying into risk group remains important for prognosis and planning further follow-up. Complete excision (Ro) remains the mainstay curative treatment. Previous dismal prognosis of recurrent or metastatic disease has only recently been improved by introduction of targeted molecular anti-receptor therapy by imatinib.

Analysis of a case with disappearance of the primary gastrointestinal stromal tumor and progressive liver metastases under long-term treatment with tyrosine kinase inhibitors

The response of gastrointestinal stromal tumors (GISTs) to tyrosine kinase receptor inhibitors (TKR-I) has been a breakthrough for small molecular therapy. We report here on the very different long-term outcome of a synchronous metastatic GIST with complete remission of the primary tumor and progressive liver metastases under TKR-I therapy. In 2003, a 52-year-old patient was diagnosed with gastric GIST and synchronous multiple liver metastases. Therapy with imatinib, 400 mg daily, was started immediately. Fifteen months later, the primary was no longer detectable by endoscopy. In 2006, progression of the liver metastases was observed. Mutation analysis of the initial biopsy specimen from the primary, as well as the biopsy from the three main liver metastases after 3 years of imatinib treatment, revealed the common KIT exon 11 deletion (W557_K558del) in all tumor samples. Two of the metastases had a separate secondary mutation in KIT exon 14 and 17, respectively, while the largest cystic metastatic lesion had no other mutation. Imatinib was then increased to a daily dose of 800 mg, and in April 2007 the treatment was changed to sunitinib. Fifty-two months after initial diagnosis, the patient died of liver failure. At no time point, relapse of the gastric primary tumor was observed. Whilst TKR-Is are commonly very effective in treating GISTs, the present case illustrates their varying effects regarding the clinical behavior and genetic variations within different tumors of the same patient after long-term treatment.

Extragastrointestinal stromal tumor arising in the rectovaginal septum: report of an unusual case with literature review

BACKGROUND

Extragastrointestinal stromal tumor (EGIST) is a rare tumor that shows features of gastrointestinal stromal tumor (GIST) outside the gastrointestinal tract, but EGIST arising in the rectovaginal septum is extremely rare.

CASE

We report a unique case of a 42-year-old woman with EGIST in rectovaginal septum. The tumor was excised locally. The patient is healthy without evidence of recurrence 11 months after surgery.

CONCLUSION

The clinical features and treatment of EGIST are not well known because few cases have been reported. Pathologically, immunohistochemistry with antibody against c-kit protein (CD117) is valuable for diagnosis of EGIST. Mitotic rate is the most reliable prognostic factor, and mutations in KIT may be a clinically useful adjunct marker in the evaluation. Surgery is the most effective treatment, and long-term follow-up is necessary.

Surgical margin status and prognosis of gastrointestinal stromal tumor

BACKGROUND

Surgery is the best treatment for primary GIST and may be curative, but resection extension/completeness impact on the prognosis remains controversial. The authors aim was to evaluate the clinicopathological (CP) parameters and surgical margins status influence on GIST patients' outcome.

MATERIALS AND METHODS

The study evaluated 113 consecutive patients with sporadic GIST; the influence of CP parameters on recurrence-free survival (RFS) and disease-specific survival (DSS) was determined by univariate analysis (UA) and multivariate analysis (MA).

RESULTS

Of 104 cases, macroscopically complete resection was achieved in 96: R0 surgical margin status in 78 and R1 in 18. Recurrence rates (12.5%) were significantly lower in R0 (9.0%) than in R1 (27.8%). Tumor > 10 cm, mitotic count > 5/50 high power field (HPF), and high-risk GIST predicted poor RFS and DSS (UA). Disease-specific survival was significantly shorter after macroscopic incomplete (R2) resection, for mixed cellular morphology, and in tumors with necrosis (UA). High-risk GIST (p = 0.016) and R2 resection (p = 0.013) predicted poor DSS of patients (MA).

CONCLUSIONS

High risk and positive macroscopic surgical margin status are parameters associated with poor disease-specific survival in GIST patients.

Ileoileal intussusception induced by a gastrointestinal stromal tumor

Background

Gastrointestinal stromal tumors are mesenchymal tumors of the gastrointestinal tract of varying malignant potential that are believed to originate from neoplastic transformation of the interstitial cells of Cajal. They may occur anywhere along the gastrointestinal tract, but most commonly arise in the stomach or small intestine. They usually grow exophytically invading adjacent organs or perforating into the peritoneal cavity. They may also cause bleeding or obstructive symptoms. Intussusception and obstruction is a very uncommon presentation of these lesions because of their tendency to grow in an exraluminal fashion.

Case presentation

We present an unusual case of ileoileal intussusception in a 79-year-old female patient caused by a gastrointestinal stromal tumor located in the terminal ileum, and review the diagnostic and therapeutic approach highlighting the difficulty in diagnosing this entity preoperatively as a cause for intestinal obstruction.

Conclusion

This case presents an unusual malignant cause of adult intussusception and highlights the importance of computed tomography scanning in the accurate diagnosis of this rare entity.

Segmental resection of the duodenum for gastrointestinal stromal tumor (GIST)

BACKGROUND

Gastrointestinal stromal tumors (GIST) are the most frequent mesenchymal tumors of the gastrointestinal tract. The biological appearance of these tumors reaches from small lesions with benign appearance to aggressive sarcomas. Only 3-5% of GISTs are localized in the duodenum. There is a controversy, if duodenal GISTs should be treated by a duodenopancreatectomy or by a limited resection of the duodenum.

CASE PRESENTATION

A 29-year-old man presented with an acute upper gastrointestinal bleeding from a submucosal tumor located in the proximal part III of the duodenum, 3 cm distal of the papilla of Vater. After an emergency laparotomy with ligation of tumor-feeding vessels in a primary hospital, definitive surgical therapy was performed by partial resection of the duodenum with a duodenojejunostomy. Histology revealed a GIST with a diameter of 2.5 cm and <5 mitoses/50 high power fields, indicating a low risk of malignancy. Therefore no adjuvant therapy with Imatinib was initiated.

CONCLUSION

GISTs of the duodenum are a rare cause of upper gastrointestinal bleeding. Partial resection of the duodenum is a warranted alternative to a duodenopancreatectomy, as this procedure has a lower operative morbidity, while providing comparable oncological results.

Value of CT in the diagnosis and follow-up of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common gastrointestinal mesenchymal tumors. Computed tomography (CT) often shows exophytic gastrointestinal masses with cystic changes, necrosis or fistula formation, and heterogeneous enhancement. After Gleevec therapy, the primary tumor, its metastases, and its recurrences can develop cystic changes and decrease in size, these findings can be satisfactorily monitored by CT. We report on 42 patients with proven GISTs, five presenting with metastases and nine patients with recurrence or development of metastases after surgery and chemotherapy.

Gastric schwannomas: endosonographic characteristics

Gastric schwannomas are rare benign neurogenic mesenchymal tumors that are usually asymptomatic but can present with variable symptoms. We retrospectively reviewed the endosonographic features of four patients with gastric schwannomas. A marginal hypoechoic halo was found in three patients with the schwannomas. The histopathological examination showed that the marginal halo on endosonography observed in the schwannomas corresponded to the lymphoid cuff. In addition, the schwannomas had lower echogenicity than the normal surrounding muscle layers. Therefore, these results suggest that gastric schwannomas can be differentiated from gastrointestinal stromal tumors by the marginal halo and the homogeneous hypoechoic endosonographic findings. These distinctions may be useful for the preoperative evaluation of gastric submucosal tumors.

Which is the optimal risk stratification system for surgically treated localized primary GIST? Comparison of three contemporary prognostic criteria in 171 tumors and a proposal for a modified Armed Forces Institute of Pathology risk criteria

BACKGROUND

This study aims to validate and compare the performance of the National Institute of Health (NIH) criteria, Huang modified NIH criteria, and Armed Forces Institute of Pathology (AFIP) risk criteria for gastrointestinal stromal tumors (GISTs) in a large series of localized primary GISTs surgically treated at a single institution to determine the ideal risk stratification system for GIST.

METHODS

The clinicopathological features of 171 consecutive patients who underwent surgical resection for GISTs were retrospectively reviewed. Statistical analyses were performed to compare the prognostic value of the three risk criteria by analyzing the discriminatory ability linear trend, homogeneity, monotonicity of gradients, and Akaike information criteria.

RESULTS

The median actuarial recurrence-free survival (RFS) for all 171 patients was 70%. On multivariate analyses, size >10 cm, mitotic count >5/50 high-power field, tumor necrosis, and serosal involvement were independent prognostic factors of RFS. All three risk criteria demonstrated a statistically significant difference in the recurrence rate, median actuarial RFS, actuarial 5-year RFS, and tumor-specific death across the different stages. Comparison of the various risk-stratification systems demonstrated that our proposed modified AFIP criteria had the best independent predictive value of RFS when compared with the other systems.

CONCLUSION

The NIH, modified NIH, and AFIP criteria are useful in the prognostication of GIST, and the AFIP risk criteria provided the best prognostication among the three systems for primary localized GIST. However, remarkable prognostic heterogeneity exists in the AFIP high-risk category, and with our proposed modification, this system provides the most accurate prognostic information.

Outcome after surgical treatment of suspected gastrointestinal stromal tumors involving the duodenum: is limited resection appropriate?

INTRODUCTION

Present surgical opinion is divided regarding the optimal method for the treatment of duodenal gastrointestinal stromal tumor (GIST) with some supporting the selective use of limited resection (LR) versus others who prefer pancreaticoduodenectomy (PD).

METHODS

A retrospective review of 22 patients who underwent surgery for suspected GIST involving the duodenum.

RESULTS

There were 15 GISTs, 1 leiomyosarcoma and 6 other non-GIST benign submucosal tumors. Seven patients underwent LR and seven underwent PD for GIST. The median follow-up was 42 (range, 2-174) months. Patients who underwent LR versus PD had similar mean disease-specific survival [144 (95% CI, 92-196) vs. 130 (95% CI, 82-127) months, P = 0.808] and recurrence rates (14% vs. 29%, P = 0.515). All recurrences occurred at distant sites. Comparison between LR versus PD demonstrated that LR was associated with a significantly shorter operation time [125 (range, 50-305) vs. 350 (range, 210-465) min., P = 0.001] but similar morbidity rate (23% vs. 43%, P = 0.357). Comparison between GIST and other benign tumors demonstrated that size was the only statistically significant distinguishing factor [8.5 (range, 2.5-18.0) vs. 2.5 (range, 1.5-8.0) cm, P = 0.014].

CONCLUSION

Benign non-GIST tumors may be distinguished from duodenal GIST as they are smaller in size. LR is a viable treatment option for suspected GIST involving the duodenum.

Laparoscopic surgery for submucosal tumors located at the esophagogastric junction and the prepylorus

BACKGROUND

Laparoscopic partial gastric resection is widely accepted as a treatment for gastric submucosal tumors (SMTs). However, SMTs of either end of the stomach are generally managed by subtotal gastrectomies or total gastrectomies. This study was conducted to evaluate surgical techniques for management of SMTs located at the ends of the stomach.

METHODS

Among 63 patients who were diagnosed and underwent laparoscopic surgery for gastric SMTs at Seoul National University Bundang Hospital from May 2003 to May 2007, 11 SMTs located at the ends of the stomach were identified. The clinicopathologic results of these 11 SMTs were analyzed.

RESULTS

Laparoscopic partial wedge resections or tumor excisions were successfully performed on all patients except for those who had prepyloric tumors. Six men and five women had SMTs at the ends of the stomach. The patients ranged in age from 21-63 years (mean 43.4 +/- 13.5 years). Of six esophagogastric junctional tumors that showed low, homogeneous contrast enhancement on computed tomography (CT) scans, five were treated by laparoscopic transgastric enucleation and one by tumor-everting resection. One esophagogastric junctional tumor that leaned toward the fundus and showed a 6-cm-diameter endophytic mass with heterogeneous enhancement on CT scan was resected by laparoscopic wedge resection. The mean operation time was 100 min (range 60-210 min). Three laparoscopy-assisted distal gastrectomies and one laparoscopic wedge resection were performed on SMTs located near the prepyloric antrum. There were no intra- or postoperative complications. Duration of postoperative hospital stay ranged from 4-7 days.

CONCLUSION

Laparoscopic local resection is an effective treatment for SMTs located at the esophagogastric junction and can be used instead of a total or proximal gastrectomy. However, gastrectomies should be considered for SMTs located near the pylorus because of the small volume of the lower third of the stomach.

Gastrointestinal stromal tumor

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. These form a distinct category of tumors characterized by oncogenic mutations of the KIT receptor tyrosine kinase in a majority of patients. KIT is used not only for diagnosis but also for targeted therapy of GISTs. Imatinib, a tyrosine kinase inhibitor, is widely used in the treatment of advanced and metastatic GISTs and has been recently employed in the neo adjuvant and adjuvant set-up with encouraging results. Certain specific mutations in an exon (such as in exon 9) of the KIT gene result in GISTs that are relatively unresponsive to the Imatinib treatment. New therapeutic agents like Sunitinib have now been approved for the treatment of Imatinib-resistant GIST. This review summarizes the salient features of GIST along with a detailed review of targeted multi-disciplinary approach to the treatment of these special tumors.