Incidence of gastrointestinal stromal tumours is underestimated: results of a nation-wide study

A nation-wide study comparing sporadic and familial adenomatous polyposis-related desmoid-type fibromatoses

Desmoid-type fibromatoses are neoplasms of fibroblastic origin, occurring sporadically or associated with familial adenomatous polyposis (FAP) coli. By comparing sporadic and FAP-associated desmoid-type fibromatoses, we tried to identify clinical characteristics, which may indicate FAP. Histopathology data of all Dutch patients with desmoid-type fibromatoses diagnosed between 1999 and 2009 were retrieved from PALGA, the nation-wide network and registry of histopathology in the Netherlands. For calculation of incidence rates, person-years from the general matched population were used. Based on polyp counts in pathological records, the cohort was divided into a FAP group and a non-FAP group. Patient- and tumor characteristics were compared between the two groups. A total number of 519 patients older than 10 years with a confirmed diagnosis of desmoid-type fibromatoses were included. Thirty-nine (7.5%) desmoid patients were documented of having FAP. The incidences of sporadic and FAP-related desmoid-type fibromatoses were 3.42 and 2,784 per million person-years, respectively. The majority of FAP patients developed desmoid-type fibromatoses after the diagnosis of FAP. Having FAP was associated with male gender [odds ratio (OR) 2.0, p = 0.034], desmoid diagnosis at an earlier age (mean 36 vs. 42 years, p = 0.031), and desmoid localization intra-abdominally (OR 18.9, p ≤ 0.001) or in the abdominal wall (OR 4.8, p ≤ 0.001), compared to extra-abdominal desmoid localization. In conclusion, patients with desmoid-type fibromatoses are at risk of underlying FAP. Especially cases with desmoid localization intra-abdominal or in the abdominal wall, and all patients younger than 60 years, have a substantial increased risk and should be referred for colonoscopy.

Diagnostic criteria, specific mutations, and genetic predisposition in gastrointestinal stromal tumors

In 1998, gastrointestinal stromal tumor (GIST) emerged as a distinct oncogenetic entity and subsequently became a paradigm of targeted therapies in solid tumors. Diagnosis of GIST relies on both histology and immunohistochemistry. Ninety-five percent of GISTs express either KIT or DOG-1. Approximately 80%-90% of GISTs harbor gain-of-function mutations of either KIT or platelet-derived growth factor receptor alpha polypeptide (PDGFRA) receptor tyrosine kinase (RTK). More than 100 different mutations have been described, some of which are associated with specific clinical and/or histological characteristics. Detection of KIT or PDGFRA mutations is recommended in advanced GISTs because they are highly predictive of tumor response to RTK inhibitors, as well as in KIT-negative cases to confirm diagnosis. In most cases, GISTs are sporadic, but in rare cases, they are related with genetic predisposition, such as neurofibromatosis type 1, Carney triad, Carney-Stratakis syndrome, and inherited KIT or PDGFRA germline mutations.

Molecular and clinicopathologic characterization of gastrointestinal stromal tumors (GISTs) of small size

Although Gastrointestinal stromal tumors (GISTs) affect about 0.0014% of the population, GISTs smaller than 1 cm (microGISTs) are detectable in about 20% to 30% of elderly individuals. This suggests that microGISTs likely represent premalignant precursors that evolve only in a minute fraction of cases toward overt GISTs. We sought histopathologic and molecular explanations for the infrequent clinical progression in small GISTs. To investigate the mechanisms of GIST progression and identify subsets with differential malignant potential, we carried out a thorough characterization of 170 GISTs <2 cm and compared their KIT/PDGFRA status with overt GISTs. The proliferation was lower in microGISTs compared with GISTs from 1 to 2 cm (milliGISTs). In addition, microGISTs were more frequently incidental, gastric, spindle, showed an infiltrative growth pattern, a lower degree of cellularity, and abundant sclerosis. The progression was limited to 1 ileal and 1 rectal milliGISTs. KIT/PDGFRA mutations were detected in 74% of the cases. The overall frequency of KIT/PDGFRA mutation and, particularly, the frequency of KIT exon 11 mutations was significantly lower in small GISTs compared with overt GISTs. Five novel mutations, 3 in KIT (p.Phe506Leu, p.Ser692Leu, p.Glu695Lys) 2 in PDGFRA (p.Ser847X, p.Ser667Pro), plus 4 double mutations were identified. Small GISTs share with overt GIST KIT/PDGFRA mutation. Nevertheless, microGISTs display an overall lower frequency of mutations, particularly canonical KIT mutations, and also carry rare and novel mutations. These molecular features, together with the peculiar pathologic characteristics, suggest that the proliferation of these lesions is likely sustained by weakly pathogenic molecular events, supporting the epidemiologic evidence that microGISTs are self-limiting lesions.

Diplopia as a presenting symptom in a gastric gastrointestinal stromal tumor

Gastrointestinal stromal tumors are the most common mesenchymal neoplasm of the gastrointestinal tract. Distant metastasis of gastrotintestinal stromal tumors occurs in ∼50% of the cases and is usually found in the liver and peritoneum. We present a patient with diplopia which was due to a metastatic gastrointestinal stromal tumor of the clivus. Transsphenoidal resection of the tumor was performed and post-operative treatment with oral imatinib mesylate was done. One month after the surgery, treatment was started with imatinib and the patient's diplopia improved within 15 days. Follow-up computed tomography was taken 2 months after the initiation of oral imatinib, and the size of the main gastric mass has decreased. To our knowledge, this is an extremely rare case of gastrointestinal stromal tumor with metastasis to the clivus with diplopia as the presenting symptom. We report our clinical findings along with a review of the relevant literature.

A prospective epidemiological study of new incident GISTs during two consecutive years in Rhône Alpes region: incidence and molecular distribution of GIST in a European region

Background:

Preliminary data indicate that the molecular epidemiology of localised gastrointestinal stromal tumour (GIST) may be different from that of advanced GIST. We sought to investigate the molecular epidemiology of sarcomas, including GIST, in the Rhone-Alpes region in France.

Patients and methods:

A prospective and exhaustive study in the Rhone-Alpes Region in France to assess the precise incidence of primary sarcomas with systematic centralised pathological review and molecular analysis was conducted for 2 consecutive years.

Results:

Among 760 patients with a confirmed diagnosis of sarcoma, 131 (17%) had a GIST. The majority of patients had gastric primaries (61%). Mutational analysis could be performed in 106 tumour samples (74%), and 71 (67%) had exon 11 mutations. PDGFRA mutations were found in 16% of cases, which is twice as high as previously reported for advanced GIST.

Conclusion:

Data indicate that PDGFRA mutations in localised GIST may be twice as high as what was previously reported in patients with advanced disease. This finding may have important consequences for patients offered adjuvant imatinib, although most of these tumours are in the low-risk group.

Evaluation of self-reported progression and correlation of imatinib dose to survival in patients with metastatic gastrointestinal stromal tumors: an open cohort study

Objectives

Self-reported progression was evaluated as a predictor of survival in patients with metastatic gastrointestinal stromal tumor (GIST).

Methods

This is a follow-up of an open cohort study of Life Raft Group (LRG) members with a diagnosis of KIT-positive metastatic GIST receiving imatinib from May 2000–December 2007 reporting their subjective response to therapy by completion of an internet-based questionnaire. Subjects received ≥ 1 year of imatinib and reported an initial positive response. Members reporting stable disease or progression were excluded. Self-reported progression-free survival (srPFS) was compared with overall survival (OS) and analyzed by starting and last reported dose.

Results

One hundred sixty-nine subjects reported a mean starting dose of 527.8±177.9 mg/d at a mean age of 53.8±11.6 years at initial diagnosis. Of those reporting progression, 66% died versus 11% of those not reporting progression (P < 0.0001). When analyzed by last reported dose, a median srPFS benefit of 27.3 months was observed for the >400 mg/d group (P = 0.0017). Sixty-two percent of subjects who initiated therapy at >400 mg/d reported a dose reduction. When analyzed by last reported dose, a significant benefit in OS (P = 0.0229) and srPFS (P = 0.0069) was observed for subjects taking 600 over 400 mg/d.

Conclusions

srPFS strongly correlated with OS. Significant advantages were observed when last reported dose was considered, as was higher daily dose. These observations suggest that careful escalation to intermediate daily doses should be investigated further for its potential to reduce the incidence and severity of adverse events, but also as a strategy against developing secondary resistance to imatinib.

NCCN Task Force report: update on the management of patients with gastrointestinal stromal tumors

The standard of care for managing patients with gastrointestinal stromal tumors (GISTs) rapidly changed after the introduction of effective molecularly targeted therapies involving tyrosine kinase inhibitors (TKIs), such as imatinib mesylate and sunitinib malate. A better understanding of the molecular characteristics of GISTs have improved the diagnostic accuracy and led to the discovery of novel immunomarkers and new mechanisms of resistance to TKI therapy, which in turn have resulted in the development of novel treatment strategies. To address these issues, the NCCN organized a task force consisting of a multidisciplinary panel of experts in the fields of medical oncology, surgical oncology, molecular diagnostics, and pathology to discuss the recent advances, identify areas of future research, and recommend an optimal approach to care for patients with GIST at all stages of disease. The task force met for the first time in October 2003 and again in December 2006 and October 2009. This supplement describes the recent developments in the field of GIST as discussed at the October 2009 meeting.

Current trends in the epidemiological and pathological characteristics of gastrointestinal stromal tumors in Korea, 2003-2004

Despite remarkable progress in understanding and treating gastrointestinal stromal tumors (GISTs) during the past two decades, the pathological characteristics of GISTs have not been made clear yet. Furthermore, concrete diagnostic criteria of malignant GISTs are still uncertain. We collected pathology reports of 1,227 GISTs from 38 hospitals in Korea between 2003 and 2004 and evaluated the efficacy of the NIH and AFIP classification schemes as well as the prognostic factors among pathologic findings. The incidence of GISTs in Korea is about 1.6 to 2.2 patients per 100,000. Extra-gastrointestinal GISTs (10.1%) are more common in Korea than in Western countries. In univariate analysis, gender, age, tumor location, size, mitosis, tumor necrosis, vascular and mucosal invasions, histologic type, CD34 and s-100 protein expression, and classifications by the NIH and AFIP criteria were found to be significantly correlated with patient's survival. However, the primary tumor location, stage and classification of the AFIP criteria were prognostically significant in predicting patient's survival in multivariate analysis. The GIST classification based on original tumor location, size, and mitosis is more efficient than the NIH criteria in predicting patient's survival, but the mechanism still needs to be clarified through future studies.

Optimal use of targeted agents for advanced gastrointestinal stromal tumours

Imatinib is the recommended 1st-line treatment for a KIT-positive unresectable and/or metastatic gastrointestinal stromal tumour (GIST). However, some patients experience intolerance to imatinib and most patients will eventually experience disease progression while on imatinib treatment. Sunitinib is approved for treatment of a GIST after disease progression on, or intolerance to, imatinib therapy. Progression may occur early or later on, in treatment and is determined by factors including initial GIST genotype and mutational status. GISTs with KIT exon 11 mutations appear to be sensitive to standard dose imatinib, and patients with GISTs exhibiting KIT exon 9 mutations whose disease has progressed on imatinib 400 mg/day have been shown to respond to imatinib 800 mg/day, albeit with a higher incidence of adverse events. Sunitinib has shown clinical benefit in all major GIST mutational subtypes, particularly in patients with wild-type or KIT exon 9 genotype and against GISTs with secondary KIT exon 13 or 14 mutations. The choice between higher-dose imatinib and sunitinib after progression on standard dose imatinib is unclear, and apart from the GIST primary resistance genotype and mutational status, individual patient factors such as tumour characteristics, drug pharmacokinetics, and other clinical factors may affect response to treatment. Individualisation of therapy may help to maximise clinical benefit of therapy in these patients.

NCCN Task Force report: update on the management of patients with gastrointestinal stromal tumors

The standard of care for managing patients with gastrointestinal stromal tumors (GISTs) rapidly changed after the introduction of effective molecularly targeted therapies involving tyrosine kinase inhibitors (TKIs), such as imatinib mesylate and sunitinib malate. A better understanding of the molecular characteristics of GISTs have improved the diagnostic accuracy and led to the discovery of novel immunomarkers and new mechanisms of resistance to TKI therapy, which in turn have resulted in the development of novel treatment strategies. To address these issues, the NCCN organized a task force consisting of a multidisciplinary panel of experts in the fields of medical oncology, surgical oncology, molecular diagnostics, and pathology to discuss the recent advances, identify areas of future research, and recommend an optimal approach to care for patients with GIST at all stages of disease. The task force met for the first time in October 2003 and again in December 2006 and October 2009. This supplement describes the recent developments in the field of GIST as discussed at the October 2009 meeting.

Gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) have emerged from being poorly defined, treatment-resistant tumors to a well-recognized, well-understood, and treatable tumor entity within only one decade. The understanding of GIST biology has made this tumor a paradigm for molecularly targeted therapy in solid tumors and provides informative insights into the advantages and limitations of so-called targeted therapeutics. Approximately 85% of GISTs harbor activating mutations in KIT or the homologous receptor tyrosine kinase PDGFRA gene. These mutations are an early event in GIST development and the oncoproteins serve as a target for the small molecule tyrosine kinase inhibitors imatinib and sunitinib. The existing and emerging treatment options demand exact morphologic classification and risk assessment. Although, KIT (CD117) immunohistochemistry is a reliable diagnostic tool in the diagnosis of GIST, KIT-negative GISTs, GISTs showing unusual morphology as well as GISTs which progress during or after treatment with imatinib/sunitinib can be a challenge for pathologists and clinicians. This review focuses on GIST pathogenesis, morphologic evaluation, promising new immunohistochemical markers, risk assessment, the role of molecular analysis, and the increasing problem of secondary imatinib resistance and its mechanisms.

Cost effectiveness of tyrosine kinase inhibitor therapy in metastatic gastrointestinal stromal tumors

BACKGROUND

Tyrosine kinase inhibitors (TKIs) such as imatinib mesylate have revolutionized the treatment of primary unresectable and/or metastatic gastrointestinal stromal tumors (GISTs), providing durable disease control and extended survival. Although most patients eventually progress on therapy, dose escalation has been shown to benefit some patients. Sunitinib, a multitargeted kinase inhibitor is effective against imatinib-resistant or intolerant GIST patients. Although the cost of TKI therapy in GIST is high, no other effective systemic treatment options exist.

OBJECTIVE

Review pharmacoeconomic studies to determine the cost effectiveness (CE) of 1st- and 2nd-line TKI therapies in GIST.

METHODS

A literature review using Medline and PubMed databases was conducted to identify published economic analyses of TKI therapy in GIST. Key results from these studies were analyzed.

RESULTS

Six pharmacoeconomic studies were identified, including three analyses of 1st-line imatinib and three analyses of 2nd-line sunitinib. These studies employed various time horizons and discount rates and modeled CE from a number of different perspectives. Most of the pharmacoeconomic studies reviewed used survival as their efficacy endpoint, projecting outcomes beyond available data to model CE. Analyses of 2nd-line sunitinib using survival additionally faced the challenge of adjusting for the effect of placebo crossover to active treatment in the pivotal phase III study. Most studies used Markov techniques with a range of transition probabilities.

CONCLUSIONS

Published pharmacoeconomic studies of 1st- and 2nd-line TKI therapy for advanced GIST employ various time horizons, discount rates, and different CE models. Consequently, these differences make comparisons between studies difficult. Studies of 1st-line imatinib concluded that imatinib was cost effective in advanced, metastatic GIST. Likewise, based on data reviewed here, 2nd-line sunitinib appears to be cost effective in patients with advanced GIST who are intolerant/resistant to imatinib. Key limitations of this review included inconsistency among the studies evaluated with regard to methodologies, countries of origination (currency and healthcare systems), and patient demographics.

Targeted therapies: the rare cancer paradigm

This review analyzes the state of the art of targeted therapies for several tumors, starting from the paradigmatic example of Imatinib treatment in chronic myelogenous leukemia (CML). We discuss how rare tumors can be models for various mechanisms of receptor tyrosine kinase (RTK) activation, and provide the opportunity to develop new therapies also for more common cancer types. We discuss the activation of the downstream RTK effectors as further targets for therapies in colorectal cancer. Finally, we highlight how a novel multidimensional approach which adds an in silico dimension to the in vitro and in vivo approach, can predict clinical results.

Gastrointestinal stromal tumor in pregnancy: a case report

Background. Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the digestive tract and are diagnosed relatively seldom in pregnancy. Case. We describe a remarkable clinical course and long-term outcome, now nine years after first diagnosis, of a massive and metastatic, with a high malignancy grade GIST case, found in and treated from the first trimester of pregnancy onwards. Conclusion. GIST occurring during pregnancy is extremely rare. However, early diagnosis is important for optimal management. The recent better understanding of oncogenesis, the use of immunohistochemistry for differential diagnosis of GISTs, and the use of imatinib mesylate as the treatment of first choice are—as shown in this case—important for care of pregnant women with this type of malignancy.

Gastrointestinal stromal tumors I: pathology, pathobiology, primary therapy, and surgical issues

Gastrointestinal stromal tumor (GISTs) are the most common connective tissue malignancies of the gastrointestinal (GI) tract, with an incidence on the order of 10-13 per million people per year. Primary therapy is usually surgical, but the recurrence rate of large, so-called high-risk tumors, with a high mitotic rate, or those arising from small bowel and colon/rectum is particularly high. The natural history, pathology, and molecular biology of GISTs are discussed in this review, as are features of increasing our analytical power of the genes altered in these tumors, surgical issues, and the translation of research findings into clinical practice. The biological features of GIST make it a model for the examination of kinase-targeted therapeutics in solid tumors.

The successful management of two pregnancies with wild type metastatic gastrointestinal stromal tumors

Aim:  To discuss the management of the uncommon situation of metastatic gastrointestinal tumour coexisting with pregnancy.

Method:  We describe two cases of women with metastatic gastrointestinal stromal tumor (GIST) who successfully achieved a full‐term pregnancy without complications and with the delivery of healthy infants. In both cases, treatment with imatinib mesylate was withheld during pregnancy because of its unknown effects and questionable safety for the developing fetus. The available data in the medical literature regarding the use and safety of imatinib and pregnancy are reviewed. We also examine whether the knowledge of the exon mutational status would have influenced treatment decisions.

Results:  Both women had wild type GIST, but with different tumor growth characteristics, treatment responses and outcomes. The first patient deferred imatinib therapy to fall pregnant and her disease progressed rapidly off treatment. The second patient had a more indolent GIST where active surgical management allowed her to experience a long durable clinical response. She potentially belongs to a pediatric subgroup which carries a better prognosis despite being off imatinib.

Conclusion:  While we have successfully managed two pregnant women with metastatic GIST, the issue of initiating imatinib therapy in treatment‐naive women, and treatment interruption in women already on therapy, remain difficult areas. Patients and their partners need to make an informed choice regarding the associated risks and the potential long‐term sequelae if pregnancies are contemplated. Further research into the natural history of wild type GIST and how to tailor subsequent treatment are needed.

Gastrointestinal stromal tumor

BACKGROUND

GISTs are a subset of mesenchymal tumors and represent the most common mesenchymal neoplasms of GI tract. However, GIST is a recently recognized tumor entity and the literature on these stromal tumors has rapidly expanded.

METHODS

An extensive review of the literature was carried out in both online medical journals and through Athens University Medical library. An extensive literature search for papers published up to 2009 was performed, using as key words, GIST, Cajal's cells, treatment, Imatinib, KIT, review of each study were conducted, and data were abstracted.

RESULTS

GIST has recently been suggested that is originated from the multipotential mesenchymal stem cells. It is estimated that the incidence of GIST is approximately 10-20 per million people, per year.

CONCLUSION

The clinical presentation of GIST is variable but the most usual symptoms include the presence of a mass or bleeding. Surgical resection of the local disease is the mainstay therapy. However, therapeutic agents, such as Imatinib have now been approved for the treatment of advanced GISTs and others, such as everolimus, rapamycin, heat shock protein 90 and IGF are in trial stage demonstrate promising results for the management of GISTs.

Cell cycle/apoptosis molecule expression correlates with imatinib response in patients with advanced gastrointestinal stromal tumors

PURPOSE

Altered expression of cell cycle/apoptosis key regulators may promote tumor progression, reflect secondary genetic/epigenetic events, and impair the effectiveness of therapy. Their expression pattern might then identify gastrointestinal stromal tumor (GIST) patient subgroups with different response to imatinib and elucidate novel therapeutic targets.

EXPERIMENTAL DESIGN

Immunohistochemical evaluation of expression of p53, p16, p21, CHK2, CCND1, BCL2, CDK4, and MDM2 was done on 353 histologically validated GIST patients enrolled into a European/Australasian phase III trial. TP53 was screened for mutations in cases with presumptive nonfunctional protein; that is, high p53 and low expression of the two downstream molecules p21 and MDM2. Results were correlated with clinicopathologic data, KIT/PDGFRA mutation status, and imatinib dosage.

RESULTS

Frequent impaired expression was found for BCL2 (78%), CHK2 (53%), p53 (50%), and p16 (47%). Stomach-originating GISTs showed significantly lower expression of p21, p16, and BCL2. KIT/PDGFRA wild-type GISTs had significant lower expression of CDK4. Eighty-eight percent of the high p53 expressers show low downstream target activation, indicating a nonfunctional p53 route. Of these high p53 expressers, 16.4% harbor a detectable TP53 mutation. Multivariate analysis, including previously identified markers, showed an independent effect of p53 and p16 on progression-free survival (PFS). Patients with high level of CHK2 and p21 showed significantly better PFS upon a high-dose regimen.

CONCLUSIONS

Impaired p53, p16, BCL2, and CHK2 expression is common in advanced GISTs. Distinct patterns of expression correlate with tumor site, genotype, and PFS. Cell cycle/apoptosis maintenance is instrumental for optimal response to imatinib.

Inherited predisposition to gastrointestinal stromal tumor

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract and are a relatively recently identified category of mesenchymal tumors. Germline mutations in a number of different genes predispose to GIST. This article discusses familial GIST syndrome, Carney triad, Carney-Stratakis syndrome, and neurofibromatosis type 1, and addresses the recognition of an inherited predisposition in GIST patients.

Contemporary pathology of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. The vast majority of GISTs harbor a KIT or PDGFRA mutation and express KIT by immunohistochemistry. However, KIT-negative tumors and tumors showing unusual morphologic features can cause major diagnostic problems. The ability to inhibit the active KIT or PDGFRA kinase with tyrosine kinase inhibitors and alternative drugs demands more than ever accurate tumor classification and risk assessment. This article focuses on the pathology of GIST, including unusual variants and morphologic changes resulting from treatment. Parameters for risk assessment, potentially helpful new immunohistochemical markers, differential diagnosis, and the application of molecular classification schemes are discussed.

Double gastrointestinal stromal tumour (GIST) of the stomach

Gastrointestinal stromal tumour (GIST), within its definition, is a gastrointestinal (GI) mesenchymal tumour containing spindle cells and showing CD 117 immunopositivity. The incidence of GISTs is estimated at 10-20/million. GISTs occur typically in people over 50 years of age. Over 95% of primary GISTs are solitary. Rarely, GISTs are multifocal and occur in young adults and children. A case of a 60-year-old women with double GIST of the stomach is reported here. The patient approached her general practitioner because of stomach ache, chronic diarrhoea and weight loss. Ultrasonography showed an abdominal tumour. During gastroscopy a submucosal tumour in the antral part of the stomach was found. Computed tomography revealed a pathological lesion between the stomach and the liver and an intramural tumour of the stomach. Two stomach tumours were found, and a Bilroth I gastrectomy was performed. Histopathological examination showed GIST in both tumours. This case shows that multifocal GISTs of the stomach can arise in older patients.

Epidemiology of gastrointestinal stromal tumors in a defined Canadian Health Region: a population-based study

The aim of this study was to determine the incidence and the clinical and pathological features of gastrointestinal stromal tumors within a nonselected, well-defined Canadian Health Region. A population-based cohort study of all adult patients diagnosed with gastrointestinal stromal tumors was conducted in the Calgary Health Region from April 2000 to March 2004. All charts and pathological specimens were reviewed for clinical, histological, and antigenic features. The age-adjusted and gender-adjusted annual incidence rate was 0.91/10(5) person-years. There was a trend for increased incidence with routine use of CD117. The only identified risk was advancing age (age >or=50; rate ratio = 4.6; P = .0006). All samples were positive for CD117. At presentation, 19% were at intermediate and 19% were at high risk of becoming malignant, with 14% being overtly metastatic. This is the first North American study to define the incidence and the clinical and pathologic features of gastrointestinal stromal tumors based on current diagnostic criteria.

A gastrointestinal stromal tumor in a patient with multiple endocrine neoplasia type 2A and metastatic medullary thyroid cancer to the ovaries

OBJECTIVE

To describe the first reported case of a patient with multiple endocrine neoplasia type 2A and a gastrointestinal stromal tumor, as well as the second reported case of metastatic medullary thyroid cancer to the ovary.

METHODS

We present the clinical, imaging, surgical, and pathologic findings of the study patient and review the relevant literature.

RESULTS

A 57-year-old woman with a clinical diagnosis of multiple endocrine neoplasia type 2A presented with a new mass in the right lower quadrant. Surgical exploration identified a 5-cm pedunculated small-bowel mass approximately 25 cm from the ileocecal junction, as well as bilaterally firm ovaries. Bilateral oophorectomy revealed medullary thyroid cancer in both ovaries and fallopian tubes. Pathology of the resected mass revealed a gastrointestinal stromal tumor of uncertain malignant potential, mitotic rate of 1/50 per high-power field, with positive staining for c-kit and smooth muscle actin and negative staining for CD34 and S-100.

CONCLUSIONS

This case is the first description of a gastrointestinal stromal tumor in a patient with multiple endocrine neoplasia type 2A, potentially representing a new paraganglioma/gastrointestinal stromal tumor syndrome. This case also highlights the possibility of the ovary as a metastatic site for medullary thyroid cancer.

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.

Gastrointestinal stromal tumors: key to diagnosis and choice of therapy

The common feature of gastrointestinal stromal tumors (GISTs) is the expression of KIT protein or acquisition of activating, constitutive mutations in the KIT or platelet-derived growth factor receptor alpha (PDGFRA) genes that are the early oncogenic events during GIST development. With these discoveries, GIST has emerged as a distinct sarcoma entity, enabling the introduction of targeted therapy using the inhibition of KIT/PDGFRA and their downstream signaling cascade. The introduction of a small-molecule tyrosine kinase inhibitor, imatinib mesylate, to clinical practice has revolutionized the treatment of patients with advanced GISTs and is currently approved as first-line treatment for patients with metastatic and/or inoperable GISTs. Mutation screening is currently a tool in GIST diagnosis, assessment of sensitivity to tyrosine kinase inhibitors, and prediction of achieving response to molecularly targeted therapy. This article discusses the histologic and molecular criteria for distinguishing GISTs from other types of sarcoma, and the molecular diagnostic tools that are currently available or in development to assist in therapy decisions.

Multiple primary sporadic gastrointestinal stromal tumors in the adult: an underestimated entity

PURPOSE

Gastrointestinal stromal tumors (GIST) are commonly regarded as solitary tumors. The occurrence of multiple lesions is considered an extraordinary event restricted to pediatric GISTs and rare hereditary conditions. Beyond these well-defined situations, the presentation of multiple synchronous lesions is commonly viewed as the result of the metastatic spreading of a single primary GIST. Based on this axiom, patients with multifocal disease are classified as advanced stage and treated as such. Whether, indeed, the detection of several lesions in sporadic adult GIST patients may be suggestive of phenomena of tumor multiplicity still needs to be clarified.

EXPERIMENTAL DESIGN

From a multicentric series of 442 consecutive cases, 26 of which with advanced disease, we selected 5 patients who presented up to three distinct GIST nodules. Five additional cases with similar characteristics were also contributed by two other institutions. The clonal relationship between the synchronous lesions was assessed by comparing KIT/PDGFRA mutation and microsatellite pattern.

RESULTS

An independent origin of the synchronous lesions was established in 6 of 10 cases. Notably, in one patient, one lesion arose in the peritoneum, which is ordinarily regarded as a site of metastasis.

CONCLUSIONS

Our data indicate that a significant fraction of GIST patients with multifocal presentation are actually affected by multiple primary tumors, suggesting that mesenchymal GIST precursor cells of these individuals are somehow primed to transformation. Thus, in the presence of multifocal GIST manifestations, an accurate characterization of the different tumor sites should be undertaken for a proper patient staging and therapy planning.

Molecular pathobiology of gastrointestinal stromal sarcomas

Gastrointestinal stromal tumors (GISTs) form an interesting group of sarcomas whose unique pathobiology provides a model of how molecularly targeted therapeutics can have a major impact on patient welfare. Approximately 85% of GISTs are driven by oncogenic mutations in either of two receptor tyrosine kinases: KIT or platelet-derived growth factor receptor alpha. We review the pivotal relationship between specific mutations in these kinase genes, the origin and pathologic spectrum of GISTs, and the response of these tumors to treatment with kinase inhibitors such as imatinib and sunitinib. Mechanisms of resistance to kinase inhibitor therapy are discussed, and targets for the next generation of therapeutics are considered. The rapid evolution in our understanding of GISTs, which stems directly from the close alliance of basic and clinical researchers in the field, illustrates the growing role of the molecular classification of solid tumors in the development of modern oncological treatments.

Subepithelial mass lesions in the upper gastrointestinal tract

The finding of a mass lesion in the upper gastrointestinal tract at endoscopy with apparent normal overlying mucosa is common. The differential diagnosis of such lesions is broad and includes those of intramural or extramural origin. Endoscopic ultrasound provides accurate imaging of subepithelial mass lesions and characterizes them according to size, echogenicity, and origin including the histologic layer if the lesion is intramural which narrows the differential diagnosis. Endoscopic ultrasound allows a guided tissue sample to be obtained for histologic confirmation which is especially important for hypoechoic lesions arising from the 3rd or 4th echogenic layers. The purpose of this article is to review the diagnosis of the more common subepithelial mass lesions with an emphasis on endoscopic ultrasound and the subsequent management or monitoring.

Optimizing the dose of imatinib for treatment of gastrointestinal stromal tumours: lessons from the phase 3 trials

Imatinib therapy for unresectable or metastatic gastrointestinal stromal tumour (GIST) is typically initiated at a dosage of 400mg/d. Two phase 3 studies investigated whether the higher dose of 800 mg/d - administered initially or upon progression on the 400-mg dose - would improve outcomes. Both the studies confirmed the 400mg/d starting dose for most patients. However, two groups benefited from the treatment with 800 mg/d of imatinib: patients with disease progression on standard-dose therapy, and patients whose tumour harbours an exon 9 mutation in KIT. Initial treatment with 800 mg/d of imatinib (400mg BID) should be considered for patients with KIT exon 9-mutant GIST. In unselected patients, dose optimisation to 800 mg/d may be warranted as a first step in managing progressive disease; such patients should be closely monitored.

The epidemiologic, health-related quality of life, and economic burden of gastrointestinal stromal tumours

BACKGROUND AND OBJECTIVES

Gastrointestinal stromal tumours (GIST) are uncommon tumours believed to arise from interstitial cells of Cajal or their precursors in the gastrointestinal (GI) tract, accounting for a small percentage of GI neoplasms and sarcomas. Given the recent recognition of GIST as a distinct cancer, as well as new treatment options available today, a review of the epidemiologic, health-related quality of life (HRQL), and economic burden of GIST is timely from a payer, provider and patient perspective and may provide guidance for treatment decision making and reimbursement.

METHODS

A systematic literature review of PubMed and five scientific meeting databases, was conducted to identify published studies and abstracts describing the epidemiologic, HRQL and economic impact of GIST. Publications deemed worthy of further review, based on the information available in the abstract, were retrieved in full text.

RESULTS AND DISCUSSION

Thirty-four publications met the review criteria: 29 provided data on GIST epidemiology, one provided cost data, three reported HRQL outcomes, and one reported cost and HRQL outcomes. The annual incidence of GIST (cases per million) ranged from 6.8 in the USA to 14.5 in Sweden, with an estimated 5-year survival rate of 45-64%. On the Functional Illness of Chronic Therapy-fatigue instrument, GIST patients scored 40.0 compared with 37.6 in anaemic cancer patients (0 = worst; 52 = least fatigue). Total costs over 10 years for managing GIST patients with molecularly targeted treatment was estimated at pounds 47 521- pounds 56 146 per patient compared with pounds 4047- pounds 4230 per patient with best supportive care.

CONCLUSIONS

The incidence of GIST appears to be similar by country; the lower estimate in one country could be explained by differences in method of case ascertainment. Data suggest that the HRQL burden of GIST is similar to that with other cancers although this requires further exploration. The value of new therapies in GIST needs to consider not only cost but also anticipated benefits and the unmet medical need in this condition.

Coexistence of gastrointestinal stromal tumor (GIST) and colorectal adenocarcinoma: A case report

Background

Gastrointestinal stromal tumors (GIST) represent the most common mesenchymal tumors of the digestive tract. Over the last ten years the management of GISTs has dramatically altered but their coexistence with other gasrointesinal tumors of different histogenesis presents a special interest. The coexistence of GISTs with other primaries is usually discovered incidentally during GI surgery for carcinomas.

Case presentation

We present here, a case of a 66-year-old patient with intestinal GIST and a synchronous colorectal adenocarcinoma discovered incidentally during surgical treatment of the recurrent GIST. Immunohistochemical examination revealed the concurrence of histologically proved GIST (strongly positive staining for c-kit, vimentin, SMA, and focal positive in S-100, while CD-34 was negative) and Dukes Stage C, (T3, N3, M0 according the TNM staging classification of colorectal cancer).

Conclusion

The coexistence of GIST with either synchronous or metachronous colorectal cancer represents a phenomenon with increasing number of relative reports in the literature the last 5 years. In any case of GIST the surgeon should be alert to recognize a possible coexistent tumor with different histological origin and to perform a thorough preoperative and intraoperative control. The correct diagnosis before and at the time of the surgical procedure is the cornerstone that secures the patients' best prognosis.

Phase II, open-label study of PTK787/ZK222584 for the treatment of metastatic gastrointestinal stromal tumors resistant to imatinib mesylate

BACKGROUND

We evaluated safety and efficacy of PTK787/ZK222584 (PTK/ZK), a novel tyrosine kinase inhibitor of KIT, platelet-derived growth factor receptors and vascular endothelial cell growth factor receptors (VEGFRs), in patients with imatinib-resistant gastrointestinal stromal tumor (GIST). This is the first study of PTK/ZK in this population.

PATIENTS AND METHODS

Patients with metastatic GIST that had progressed after >/= 4-week treatment with imatinib mesylate were eligible. Prior VEGFR-2 inhibitor therapy was not permitted. PTK/ZK 1250 mg orally once-daily was administered to 15 patients (accrued as a two-stage procedure), most of whom (n = 11) had been unsuccessfully treated with imatinib 800 mg daily, until treatment failure. Patients were monitored at 4- to 8-week intervals.

RESULTS

All 15 patients enrolled were eligible; two (13%) achieved partial response (PR), eight (53%) had stable disease (SD) >/=3 months, and five (33%) progressed. The clinical benefit rate (PR + SD) was 67% (95% CI 38% to 86%). Median time to progression was 8.5 months (range 0.9-24.8+ months). Three patients had not progressed at the time of analysis, including one PR at 24.8 months and two SDs at 16.6 and 18.6 months on treatment. PTK/ZK was generally well tolerated.

CONCLUSION

PTK/ZK 1250 mg p.o. once daily is active and well tolerated in patients with imatinib-resistant GIST.

Coexistence of gastrointestinal stromal tumors with other neoplasms

BACKGROUND

The purpose of this study was to assess the prevalence of other neoplasms in patients with gastrointestinal stromal tumors (GISTs) and to compare clinical and histopathological data in patients with a GIST and accompanying neoplasms and in patients with GIST only.

METHODS

The analysis encompassed 82 patients with a GIST from among 330 300 patients whose surgical specimens, biopsies, and autopsies were evaluated between January 1989 and June 2006. A subgroup of patients with other types of neoplasms was selected.

RESULTS

Other neoplasms in patients with a GIST were diagnosed in 22 of the 82 (26.8%) patients. The most common accompanying neoplasms were colorectal (nine cases) and gastric (four cases) adenocarcinoma, as well as pancreatic adenocarcinoma (three cases). There was a tendency toward more common localization of a GIST in the small intestine in patients with other neoplasms than in patients with a GIST alone (P < 0.09). Tumors with very low risk of aggressive behavior were more frequent in patients with a GIST accompanied by other neoplasms than in the other group (P < 0.05). No phenotypic differences in GIST cells were found between the two groups.

CONCLUSIONS

In almost 27% of the study population, GISTs coexisted with other neoplasms. A greater proportion of patients with a GIST localized in the small intestine and/or characterized by a very low risk of aggressive behavior and accompanying other neoplasms, compared with a GIST alone, most likely reflects the fact that in the first group, GISTs tended to be an incidental finding during surgery. The results were affected by patient selection and the type of tissue material available.

Disease progression following imatinib failure in gastrointestinal stromal tumors: role of surgical therapy

Gastrointestinal stromal tumors (GISTs) represent the most common mesenchymal neoplasms of the GI tract. The optimal management of GISTs has been evolving rapidly over the past 5 years and depends on proper histopathologic and radiologic diagnosis as well as appropriate multidisciplinary medical and surgical treatments. Complete surgical resection of primary localized GIST with negative margins remains the best therapeutic option today. In the setting of locally advanced or metastatic disease, imatinib mesylate has emerged as the initial treatment of choice, administered either as cytoreductive or as definitive treatment. Surgery or ablative modalities in this setting are becoming increasingly employed, particularly when all disease becomes amenable to gross resection or destruction, or to manage complications arising from the disease following imatinib failure. We report on the surgical management of an unusual and clinically significant complication following progression of disease secondary to imatinib resistance. The role of surgical therapy in the management of GIST complications following resistance to imatinib and the integration of surgical and molecular therapy of locally advanced or metastatic GISTs are discussed.

A modification of NIH consensus criteria to better distinguish the highly lethal subset of primary localized gastrointestinal stromal tumors: a subdivision of the original high-risk group on the basis of outcome

BACKGROUND

By reappraising the National Institutes of Health (NIH) consensus criteria, we worked on establishing a modified scheme to identify highly lethal gastrointestinal stromal tumors (GISTs), which have an imperative demand for sequencing analysis to assess the suitability of an adjuvant imatinib trial.

METHODS

Clinicopathologic features, including NIH and modified schemes, were retrospectively analyzed for 289 patients with localized GISTs. We combined the very low/low-risk GISTs into a single "risk level I" group (5 cm and >10/50 HPF, with the rest of high-risk GISTs defined as "risk level III."

RESULTS

The cumulative 5-year rate of disease-specific survival (DSS) for all 289 patients was 82%, and the DSS rates for patients with GISTs classified as risk levels I to IV were 100%, 96%, 67%, and 25% at 5 years, respectively. The prognostic differences were striking between the risk level II and III groups (P < .0001) and between the risk level III and IV groups (P = .0002). The higher risk level of our scheme represented the strongest independent adverse factor (risk ratio [RR] = 11.299 for risk level III; RR = 33.815 for risk level IV; P < .0001), followed by mixed/epithelioid histology (RR = 2.837, P = .003) and older age (>or=70 years, RR = 1.955, P = .044).

CONCLUSIONS

Remarkable prognostic heterogeneity exists in the high-risk category of the NIH scheme, which is not as effective as the modified criteria in identifying highly lethal GISTs that we classified as risk level IV.

Approval summary: sunitinib for the treatment of imatinib refractory or intolerant gastrointestinal stromal tumors and advanced renal cell carcinoma

PURPOSE

To describe the Food and Drug Administration (FDA) review and approval of sunitinib malate (Sutent). Sunitinib received regular approval for the treatment of gastrointestinal stromal tumor (GIST) after disease progression or intolerance to imatinib mesylate (Gleevec). Additionally, sunitinib received accelerated approval for the treatment of advanced renal cell carcinoma.

EXPERIMENTAL DESIGN

For the GIST indication, FDA reviewed data from a randomized, placebo-controlled trial with supportive evidence from a single-arm study. For the advanced renal cell carcinoma indication, FDA reviewed data from two single-arm studies of patients with cytokine-refractory metastatic renal cell carcinoma.

RESULTS

In patients with imatinib refractory or intolerant GIST, time-to-tumor progression of sunitinib-treated patients was superior to that of placebo-treated patients. Median time-to-tumor progression of sunitinib-treated patients was 27.3 weeks, compared with 6.4 weeks for placebo-treated patients (P < 0.0001). Partial responses were observed in 6.8% of sunitinib-treated patients. In patients with metastatic renal cell carcinoma, partial responses were observed in 25.5% (95% confidence interval, 17.5, 34.9) and 36.5% (95% confidence interval, 24.7, 49.6) of patients treated with sunitinib. Median response durations were 27.1 and 54 weeks. The most common adverse events attributed to sunitinib included diarrhea, mucositis, skin abnormalities, and altered taste. Reductions in left ventricular ejection fraction and severe hypertension were also more common in sunitinib-treated patients.

CONCLUSIONS

On January 26, 2006, the FDA approved sunitinib for the treatment of patients with imatinib refractory or intolerant GIST. Accelerated approval was granted for the treatment of advanced renal cell carcinoma.

Clinical, radiological, and pathological findings in four children with gastrointestinal stromal tumors of the stomach

The incidence of gastrointestinal stromal tumors (GISTs) in children is exceptionally low. However, during the last decade these tumors attracted increasing attention, because they were found to express the cell surface transmembrane receptor kit (CD117) that has tyrosine kinase activity. This tyrosine kinase can be semi-selectively inhibited by signal transduction inhibitors such as imatinib mesylate (Glivec), which is a competitive inhibitor of c-kit, c-abl, platelet-derived growth factor receptor-alpha (PDGFR-alpha) and PDGFR-beta, and abl-related gene (arg). The authors present the clinical, radiographic, and pathological findings of 4 children who were diagnosed with gastric GIST. One of them had an incomplete Carney triad including GIST and mediastinal paraganglioma. All 4 patients presented with anemia and anemia-related symptoms and underwent total resection of the tumor. One patient received additional chemotherapy (in the pre-imatinib era) and 2 patients received a short course of imatinib mesylate. With a follow-up of 116, 55, 23, and 10 months all patients are alive in first complete continuous remission. In children and adolescents, particularly in female patients, GISTs should be included in the differential diagnosis of anemia secondary to gastrointestinal hemorrhage. Complete surgical resection is the mainstay of treatment for this tumor, with imatinib mesylate restricted to patients with advanced or metastatic tumors. Since late recurrences (up to 30 years following initial diagnosis) are reported, a life-long follow-up is mandatory in these patients.