Gastrointestinal stromal tumours (GISTs): a clinicopathological and molecular study of 66 cases

Development of a multi-phase CT-based radiomics model to differentiate heterotopic pancreas from gastrointestinal stromal tumor

BACKGROUND

To investigate whether CT-based radiomics can effectively differentiate between heterotopic pancreas (HP) and gastrointestinal stromal tumor (GIST), and whether different resampling methods can affect the model's performance.

METHODS

Multi-phase CT radiological data were retrospectively collected from 94 patients. Of these, 40 with HP and 54 with GISTs were enrolled between April 2017 and November 2021. One experienced radiologist manually delineated the volume of interest and then resampled the voxel size of the images to 0.5 × 0.5 × 0.5 mm3, 1 × 1 × 1 mm3, and 2 × 2 × 2 mm3, respectively. Radiomics features were extracted using PyRadiomics, resulting in 1218 features from each phase image. The datasets were randomly divided into training set (n = 66) and validation set (n = 28) at a 7:3 ratio. After applying multiple feature selection methods, the optimal features were screened. Radial basis kernel function-based support vector machine (RBF-SVM) was used as the classifier, and model performance was evaluated using the area under the receiver operating curve (AUC) analysis, as well as accuracy, sensitivity, and specificity.

RESULTS

The combined phase model performed better than the other phase models, and the resampling method of 0.5 × 0.5 × 0.5 mm3 achieved the highest performance with an AUC of 0.953 (0.881-1), accuracy of 0.929, sensitivity of 0.938, and specificity of 0.917 in the validation set. The Delong test showed no significant difference in AUCs among the three resampling methods, with p > 0.05.

CONCLUSIONS

Radiomics can effectively differentiate between HP and GISTs on CT images, and the diagnostic performance of radiomics is minimally affected by different resampling methods.

Ruptured gastro-intestinal stromal tumor as a surgical emergency: A case report and literature review

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. GISTs of the small bowel are rare, and often present with an abdominal mass and/or bleeding. Chemotherapy and surgery are the mainstay of therapy. Here, we discuss an unusual case of a ruptured jejunal GIST with hemoperitoneum and recurrence despite surgical excision followed by Imatinib treatment. Forty-five cases of ruptured small intestinal GISTs were identified in the literature. Most cases were in males and were found to be at the site of the jejunum.

Role of Multidetector CT Imaging in the Risk Stratification of Gastrointestinal Stromal Tumors (GISTs)–A Retrospective Analysis

Background Gastrointestinal stromal tumors (GISTs) are the most common gastrointestinal mesenchymal neoplasms which can arise from any part of the gastrointestinal tract (GIT) or an extraintestinal location. Size and the organ of origin are the major imaging inputs expected from the radiologist. However, it is worthwhile to find out which imaging characteristics on MDCT correlate with risk stratification. This knowledge would help the clinician in treatment planning and prognostication. The aim of this retrospective study is to evaluate the various MDCT imaging characteristics of GISTs and find out which parameters have significant association with risk and subsequent development of metastasis on follow-up whenever it was possible.

Materials and Methods This is a retrospective study conducted on 45 histopathologically proven cases of GIST from two institutions by searching from the digital archives. The following imaging parameters were analyzed: maximum size in any plane, organ of origin, shape (round, ovoid or irregular), margin (well-defined or ill-defined), surface (smooth or lobulated), percentage of necrosis, growth pattern, enhancement characteristics–both intensity (mild, moderate or significant) and pattern (homogenous vs. heterogenous), calcification, infiltration into adjacent organs, and presence of metastasis at presentation or on follow-up.

Results CT morphological parameters of significance in risk stratification as per our study include tumor necrosis, predominant cystic change, irregular and lobulated shape/surface characteristics, and adjacent organ infiltration.

The parameters which were associated with development of metastasis were size > 5 cm, necrosis > 30%, and the presence of adjacent organ infiltration.

Conclusion The radiologist has an important role in ascertaining the size of tumor as well as the organ of origin accurately to guide the clinician in risk calculation and subsequent prognostication. In addition, certain CT characteristics mentioned above, namely, tumor size, significant necrosis/cystic changes, irregular/lobulated contour, and invasion of adjacent organs, help in risk stratification and in predicting metastasis/poor prognosis.

Retrospective analysis of prognostic factors affecting the recurrence and disease-free survival following surgical management of gastrointestinal stromal tumors

Objectives

The aim of this study was to evaluate the prognostic factors effecting recurrence risk and disease-free survival of the patients who were diagnosed as gastrointestinal stromal tumor after complete resection of the tumor with or without adjuvant therapy.

Material and Methods

Between the years 2005 and 2013, data of 71 patients including clinical and demographic features, tumor localizations, pathologic examinations, survival and recurrence rates were enrolled into this retrospective study.

Results

Male/female ratio was 1.71, and mean age was 60.27 ± 14.65 years. Forty-two (59.2%) patients had tumor in stomach, 16 (22.5%) in small bowel, whereas 12 (16.9%) had extra-gastrointestinal system and one patient (%1.4) had rectal localization. Modified NIH risk stratification scheme categorized 9 (12.68%) patients in very low-, 12 (16.90%) in low-, 21 (29.58%) patients in moderate-and 29 (40.85%) patients in high-risk group. Twenty-four (33.8%) patients had a metastatic disease at follow-up while 13 (18.3%) patients were metastatic at admission. R0 resection was successfully performed in 51 (71.8%) patients, while R1 resection in 9 (12.7%) and R2 resection in 11 (15.5%) were achieved. Mean follow-up time was 47.12 ± 33.52 months (range, 1-171 months). Nineteen (26.8%) patients demonstrated recurrence with a mean time of 22.16 ± 15.89 months (range, 3-57 months). During follow-up 17 (23.9%) patients were deceased. In univariate analysis, high-risk group, small bowel and extra-gastrointestinal system localization, R1-2 resection, necrosis, positive resection margin and invasion of surrounding tissues, metastatic disease and adjuvant therapy were statistically significant in terms of recurrence. Multivariate analysis presented small bowel and extra-gastrointestinal system localization, R2 resection, mitoses count, invasion and adjuvant therapy as independent prognostic risk factors affecting disease-free survival rates. The 1, 3 and 5 years of disease-free survival rates of the patients were 89.6%, 75.4%, 64.3%, respectively.

Conclusion

As mentioned in the literature, the mainstay of curative therapy of gastrointestinal stromal tumor is surgery. In our study, not only small bowel, extra-gastrointestinal system localization and invasion of surrounding tissues by tumor, but also R2 resection that complicate the local control of the disease were represented as independent adverse prognostic factors for disease-free survival. Unfavourable clinical outcomes of adjuvant therapy over the disease-free survival was linked to higher tumor stage with metastatic disease and emphasized that prospective trials with more cases should be practiced.

Prognostic Value of Her2/neu Expression in Gastrointestinal Stromal Tumors: Immunohistochemical Study

BACKGROUND

Gastrointestinal stromal tumor (GIST) is a relatively rare type of neoplasms. In Egypt, it represents 2.5% of gastrointestinal tumors and 0.3% of all malignancies. Most of the GISTs develop in the stomach.

AIM

To reveal the significance of Her2/neu immunohistochemical expression in GIST and its correlation with other histopathologic parameters and tumor relapse after regular follow-up.

PATIENTS AND METHODS

This study is a retrospective and prospective cohort. It included 32 patients with GISTs, who were resectable with no distant metastasis. Immunohistochemical staining by Her2/neu was performed after complete surgical resection of the tumors with preservation of the pseudocapsule.

RESULTS

In total, 53.1% of cases were men and 46.9% women. Tumors were classified into low-risk (25%), intermediate-risk (21.9%), and high-risk groups (53.1%). Her2/neu expression was negative in 56.3% of GISTs and positive in 43.7%. Its expression was significantly correlated with risk grade (P = .04), tumor size (P = .001), mitotic count (P = .00), and increased risk of relapse (P = .00). Furthermore, tumor relapse was significantly correlated with the tumor mitotic counts (P = .00). Using kappa agreement test, it showed that 4 mitotic counts/50 high-power fields (HPF) was the cutoff value with which the tumor might be associated more with relapse, with 83% sensitivity, 70% specificity, and P value of .003.

CONCLUSIONS

Her2/neu might be used as an independent prognostic marker for tumor recurrence after complete resection of GIST, and the cutoff value of mitotic count that might predict tumor relapse is 4/50 HPF. However, more clinical studies with greater number of cases with fluorescent in situ hybridization integration are recommended.

Clinico-pathological characteristics and prognostic factors of gastrointestinal stromal tumors among a Chinese population

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms in the gastrointestinal tract, exhibiting wide variability in their biological behavior. The aim of the present study was to investigate the clinicopathological characteristics and prognostic factors of GISTs in Chinese patients. All GIST cases (n=182) retrieved from the pathology database and the archived files in Shanghai Changzheng Hospital between January 2011 and December 2014 were reviewed. The clinical symptoms, preoperative investigations, treatments, pathological characteristics and follow-up data of these patients were reviewed, and univariate and multivariate survival analyses were performed. A total of 73.1% of the GISTs were located in the stomach, and the most common three symptoms included abdominal pain (30.2%), dyspepsia (23.1%) and gastrointestinal bleeding (21.4%). Univariate analysis revealed that larger tumor size (P<0.001), higher mitotic rate (P<0.001), aggressive behavior (P<0.001), negative smooth muscle actin expression (P=0.009) and palliative resection (P<0.001) contributed toward poor overall survival (OS). In addition, non-gastric disease location (P<0.001), larger tumor size (P<0.001), higher mitotic rate (P=0.004), aggressive behavior (P<0.001) and palliative resection (P<0.001) were associated with poor relapse-free survival (RFS). Multivariate analysis indicated that mitotic rate [hazard ratio (HR=3.761, P=0.015)] and aggressive behavior (HR=3.916, P=0.010) were independent risk factors for OS, while non-gastric location (HR=4.740, P=0.002) and aggressive behavior (HR=4.009, P=0.004) were independent risk factors for RFS. The present study provided information on the clinicopathological characteristics and epidemiology of GISTs in the Chinese population. Non-gastric disease location, higher mitotic rate and tumor metastasis or local invasion prior to treatment were identified as predictors of a poor prognosis.

Gastrointestinal autonomic nerve tumors: a clinical review

PURPOSE

Gastrointestinal autonomic nerve tumors (GANTs) are believed to be rare accounting for 1 % of all malignant gastrointestinal tumors. Many gastrointestinal surgeons and gastroenterologists are unaware of this entity. This review aims to highlight the salient clinical features and prognosis of GANTs.

METHODS

Using the common search engines and manual cross-referencing, a search of the English literature was conducted for "gastrointestinal autonomic nerve tumor."

RESULTS

All of the published literature on GANTs is either case reports or small case series. From 49 retrieved articles, a total of 107 GANT cases were collected with a mean age of 54 years and equal male to female preponderance. The most commonly affected site was small bowel followed by stomach. Esophageal and colorectal GANTs were less frequent. Clinical presentation was variable ranging from non-specific symptoms, abdominal pain, weight loss, iron-deficiency anemia, to obstruction and gastrointestinal bleeding. Acute presentation due to free rupture or perforation with subsequent peritonitis was extremely rare. Endoscopic and radiological investigations were valuable in tumor localization and determination of distant spread. Thirteen patients were lost to or had no follow-up, leaving 94 patients for long-term outcome analysis. All patients were treated by radical surgical resection of the involved organ as this offered the only hope of cure. Local recurrence, metastases, or both developed in 40 % of cases despite radical surgical resection. Resection for local recurrences and hepatic metastases was feasible in some selected cases. Response to adjuvant chemoradiation was poor and imatinib mesilate was effective in cases of metastatic or inoperable CD117-positive GANTs.

CONCLUSION

Radical surgical resection of GANTs is the mainstay of treatment. The aggressive behavior after radical resection coined with the poor response to adjuvant chemotherapy call for the urgent need to develop new adjuvant therapies.

Comparative study of the different degrees of risk of gastrointestinal stromal tumor

OBJECTIVE

To evaluate the applicability of the main categories of risk and morphological factors in the prognosis of gastrointestinal stromal tumors.

METHODS

we retrospectively studied fifty-four cases of GIST, assessing the main prognostic factors of this neoplasis: risk levels, topography, size, mitotic index, necrosis, histological subtype and immunophenotype. We also verified their association and the reduction of overall survival.

RESULTS

Univariate analysis showed that tumors with mitoses number greater than 5 per 50CGA (high-power fields), the presence of necrosis and a high risk for both the systems proposed by Fletcher and Miettinen had a significant association with reduced survival (p = 0.00001, 0.0056, 0.03 and 0.009, respectively). The remaining analyzed factors (size, histological subtype, topography and immunophenotype) had no such association. Multivariate analysis (Jacard index) showed that the Miettinen degree of risk was the one that best correlated with prognosis.

CONCLUSION

the risk criteria of Fletcher and Miettinen are important in assessing the prognosis of patients with gastrointestinal stromal tumors, especially the latter, which adds to the mitotic index and the presence of tumor necrosis.

Practical aspects of risk assessment in gastrointestinal stromal tumors

INTRODUCTION

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the gastrointestinal tract, which are characterized in the majority of cases by activating mutations in KIT and platelet-derived growth factor receptor alpha (PDGFRA). The introduction of tyrosine kinase inhibitors has revolutionized the management of patients with metastatic GIST. However, complete surgical resection remains the mainstay of management for those with localized disease. Recently, three large trials have confirmed the benefit of adjuvant imatinib therapy in patients who were at high risk of recurrence following complete resection. In this setting, it is critical that oncologists understand the various GIST risk assessment criteria and be able to apply these methods to accurately assess the risk of recurrence and the need for adjuvant imatinib therapy.

PURPOSE

The aim of this review is to outline the risk stratification systems currently available to oncologists who are treating patients with GIST, so they can be optimally applied for clinical decision-making.

Does immunohistochemistry provide additional prognostic data in gastrointestinal stromal tumors?

BACKGROUND

To investigate the predictive and prognostic effects of clinicopathologic and immunohistochemical (IHC) features in patients with gastrointestinal stromal tumours (GISTs).

MATERIALS AND METHODS

Fifty-six patients who were diagnosed with GIST between 2002 and 2012 were retrospectively evaluated. Relationships between clinicopathologic/immunohistochemical factors and prognosis were investigated.

RESULTS

Median overall survival (OS) of the whole study group was 74.9 months (42.8-107.1 months), while it was 95.2 months in resectable and 44.7 months in metastatic patients respectively (p=0.007). Epitheliolid tumor morphology was significantly associated with shortened OS as compared to other histologies (p=0.001). SMA(+) tumours were significantly correlated with low (<10/50HPF) mitotic activity (p=0.034). Moreover, SMA(+) patients tended to survive longer and had significantly longer disease-free survival (DFS) times than SMA (-) patients (37.7 months vs 15.9 months; p=0.002). High Ki-67 level (≥30%) was significantly associated with shorter OS (34 vs 95.2 months; 95%CI; p=0.001). CD34 (-) tumours were significantly associated with low proliferative tumours (Ki-67<%10) (p=0.026). Median PFS (progression-free survival) of the patients who received imatinib was 36 months (27.7-44.2 months). CD34 (-) patients had significantly longer PFS times than that of negative tumours; (50.8 vs 29.8 months; p=0.045). S100 and desmin expression did not play any role in predicting the prognosis of GISTs. Multivariate analysis demonstrated that ≥10/50HPF mitotic activity/HPF was the only independent factor for risk of death in GIST patients.

CONCLUSIONS

Despite the negative prognostic and predictive effect of high Ki-67 and CD34 expression, mitotic activity remains the strongest prognostic factor in GIST patients. SMA positivity seems to affect GIST prognosis positively. However, large-scale, multicenter studies are required to provide supportive data for these findings.

Classification of canine nonangiogenic, nonlymphogenic, gastrointestinal sarcomas based on microscopic, immunohistochemical, and molecular characteristics

Canine nonangiogenic, nonlymphogenic, gastrointestinal sarcomas have been previously diagnosed as gastrointestinal stromal tumors (GIST), leiomyosarcomas, or nonspecified spindle cell sarcomas, but diagnostic criteria for each entity are poorly defined. We propose a classification for canine nonangiogenic, nonlymphogenic, gastrointestinal sarcomas based on microscopic, immunohistochemical, and molecular characteristics. Applying the classification to 40 canine nonangiogenic, nonlymphogenic, gastrointestinal sarcomas documented its diagnostic and prognostic value. Eighteen (45%) sarcomas were classified as GIST based on positive KIT immunoreactivity. All GISTs were positive for vimentin, 14 (78%) were positive for S-100, and 6 (33%) were positive for smooth muscle actin (SMA). In contrast to their human counterparts, canine GISTs occurred mainly in the small intestine (67%) but commonly metastasized (5/18) to liver, lymph nodes, and omentum. Six GISTs had an activated KIT mutation in exon 11 of c-Kit, but no mutations were detected in exons 8, 9, 13, and 17. Twelve (30%) sarcomas were classified as leiomyosarcomas based on positive labeling for SMA and negative labeling for KIT. Four of these neoplasms were well differentiated leiomyosarcomas characterized by weak to no labeling for vimentin, and 8 were poorly differentiated leiomyosarcomas characterized by strong labeling for vimentin. None of the leiomyosarcomas metastasized, but poorly differentiated leiomyosarcomas had a higher risk of local invasion. Ten (25%) sarcomas were classified as non-GIST/nonleiomyosarcomas that were negative for KIT and SMA but positive for vimentin and either S-100 and/or PGP 9.5. These neoplasms most likely represent sarcomas of neurogenic differentiation resembling Schwann cells or perineurial or endoneurial fibroblasts, respectively.

MAPKAP kinase 2 overexpression influences prognosis in gastrointestinal stromal tumors and associates with copy number variations on chromosome 1 and expression of p38 MAP kinase and ETV1

PURPOSE

ETV1 has been proposed to be activated by KIT mutations in gastrointestinal stromal tumors (GIST). The aim of the study was to evaluate the clinical role of ETV1 and associated proteins in GIST.

EXPERIMENTAL DESIGN

Expressions of ETV1, MAPKAP kinase 2 (MAPKAPK2), phosphorylated p38 MAP kinase (pp38), phosphorylated MSK1 (pMSK1), phosphorylated RSK1, COP1, and KIT protein were determined immunohistochemically in 139 GISTs. Sequence analysis of KIT, PDGFRA, and MAPKAPK2 and FISHs of ETV1 as well as chromosomes 1 and 7 were done.

RESULTS

Prominent ETV1 expression was seen in 50% of GISTs, but no correlation with clinical outcome was found. Correlation of ETV1 expression and KIT mutation was seen in 60% of cases. MAPKAPK2 overexpression (n = 62/44.6%) correlated with pp38 expression (P = 0.021, χ(2) test) and alterations of chromosome 1 (n = 17, P = 0.024, χ(2) test). In one of 20 sequenced cases with high MAKAPK2 expression, a putative damaging MAPKAPK2 gene mutation was found. All relapsing GISTs with very low/low risk according to Fletcher showed high MAPKAPK2 and KIT expression. MAPKAPK2 overexpression was an independent prognostic factor for disease-free survival (P = 0.006, Cox regression).

CONCLUSION

ETV1 is not universally overexpressed in GIST and seems to also be induced by pathways other than KIT mutation. Nevertheless, its clinical relevance is low. Overexpression of ETV1 inhibitor MAPKAPK2 is associated with shorter survival in GIST, indicating a clinically relevant role of this gene not reported previously. Patients with low-risk GISTs showing MAPKAPK2 overexpression might profit from early adjuvant tyrosine kinase inhibitor therapy.

Gastrointestinal stromal tumors: a review of the literature

Gastrointestinal stromal tumors are mesenchymal neoplasms with a spectrum of histologic appearances and biologic activity. The morphologic classification of these lesions has evolved over time, and molecular analysis has led to a better understanding of their nature. The histologic differential diagnosis for these lesions is broad and includes many spindle cell lesions of the gastrointestinal tract, including neoplasms of true smooth muscle and neural origin, proliferating fibrous lesions, metastatic neoplasms, and primary sarcomas of vascular and adipose origin. Immunohistochemical studies that include CD117 have become invaluable in the classification of mesenchymal lesions arising in the gastrointestinal tract. Treatment of gastrointestinal stromal tumors has historically been involved surgery, but the use of the chemotherapeutic agent imatinib mesylate for advanced disease has made accurate classification even more important. The molecular features have not only allowed us to understand the pathogenesis of these tumors but also have proven to be associated with response to kinase inhibitors.

Development and validation of a prognostic nomogram for recurrence-free survival after complete surgical resection of localised primary gastrointestinal stromal tumour: a retrospective analysis

BACKGROUND

Adjuvant imatinib mesylate prolongs recurrence-free survival (RFS) after resection of localised primary gastrointestinal stromal tumours (GIST). We aimed to develop a nomogram to predict RFS after surgery in the absence of adjuvant therapy to help guide patient selection for adjuvant imatinib therapy.

METHODS

A nomogram to predict RFS based on tumour size (cm), location (stomach, small intestine, colon/rectum, or other), and mitotic index (<5 or > or =5 mitoses per 50 high-power fields) was developed from 127 patients treated at Memorial Sloan-Kettering Cancer Center (MSKCC), New York, NY, USA. The nomogram was tested in patients from the Spanish Group for Research on Sarcomas (GEIS; n=212) and the Mayo Clinic, Rochester, MN, USA (Mayo; n=148). The nomogram was assessed by calculating concordance probabilities and testing calibration of predicted RFS with observed RFS. Concordance probabilities were also compared with those of three commonly used staging systems.

FINDINGS

The nomogram had a concordance probability of 0.78 (SE 0.02) in the MSKCC dataset, and 0.76 (0.03) and 0.80 (0.02) in the validation cohorts. Nomogram predictions were well calibrated. Inclusion of tyrosine kinase mutation status in the nomogram did not improve its discriminatory ability. Concordance probabilities of the nomogram were better than those of the two NIH staging systems (0.76 [0.03] vs 0.70 [0.04, p=0.04] and 0.66 [0.04, p=0.01] in the GEIS validation cohort; 0.80 [0.02] vs 0.74 [0.02, p=0.04] and 0.78 [0.02, p=0.05] in the Mayo cohort) and similar to those of the AFIP-Miettinen staging system (0.76 [0.03] vs 0.73 [0.004, p=0.28] in the GEIS cohort; 0.80 [0.02] vs 0.76 [0.003, p=0.09] in the Mayo cohort). Nomogram predictions of RFS seemed better calibrated than predictions made with the AFIP-Miettinen system.

INTERPRETATION

The nomogram accurately predicts RFS after resection of localised primary GIST and could be used to select patients for adjuvant imatinib therapy.

Clinical and molecular characteristics of gastrointestinal stromal tumors in the pediatric and young adult population

Gastrointestinal stromal tumors (GISTs) typically occur late in life; however, there also are reports of pediatric and young adult patients. This rare subset of GISTs has clinicopathologic and molecular features distinct from their adult counterparts. Most pediatric GIST patients are female and often present with multifocal tumors that are epithelioid in nature. Although these young patients often have metastatic disease, it progresses slowly. Most pediatric GISTs lack the gain-of-function mutation in KIT or PDGFRA commonly found in adult cases. Expression profiling and genomic studies of pediatric GISTs show distinct molecular signatures, suggesting a unique origin as compared with adult GISTs. We and others have shown that the insulin-like growth factor 1 receptor may have a prominent role in driving KIT/PDGFRA mutation-negative adult and pediatric GISTs, and clinical trials are currently being designed to exploit these types of discoveries.

Small-bowel tumors in the elderly 65+ years: 10 years of experience

Primary, secondary, benign or malignant tumorous diseases of the small intestine are rare. They are very often diagnosed by accident or as a cause of acute abdomen. Less serious symptoms can be overseen mainly in older patients. This work represents a prospective evaluation of a diagnostic and therapeutic algorithm in the management of the small-intestine tumor below the ligamentum Treitzi in patients over 65 years of age.

RESULTS

A population of 96 patients who underwent surgery for a small-intestinal tumor in our hospital from 1996 to 2006 is presented. Thirty-four of these patients were older than 65 years. Ultrasound of the small intestine was sufficient to make the diagnosis in 21 of them. Elective surgery (laparoscopy was highly preferred) could be offered to 31 of these older patients. Perioperative mortality was zero.

CONCLUSION

The small-bowel ultrasound can be recommended as the first choice method. All complaints regarding the gastrointestinal tract should be verified. Older patients can be safely offered an elective laparoscopic surgery with acceptable morbidity and mortality.

Risk stratification of patients diagnosed with gastrointestinal stromal tumor

Accurate risk stratification of gastrointestinal stromal tumors (GISTs) has become increasingly important owing to emerging adjuvant systemic treatments. All GISTs have been considered to have some malignant potential, but this hypothesis is now seriously challenged by studies indicating that microscopic gastric GISTs that are common in the general population probably have little or no malignant potential. The National Institutes of Health (NIH) consensus classification system, based on tumor size and mitotic count, is commonly used to assess patient prognosis after surgical resection. Large retrospective cohort studies from several countries now uniformly indicate that the NIH classification carries substantial prognostic value. In particular, patients with high-risk GIST (approximately 44% of all) have substantially poorer outcome than those with intermediate-risk (24%) or low/very low-risk GIST (32%), whose survival is not markedly inferior to that of the general population in some studies. Gastric GISTs (approximately 58% of all GISTs) have a lower risk of recurrence than nongastric tumors of the same size and mitotic count, and tumor rupture confers clearly increased risk. These 2 important risk stratification factors are not considered in the NIH classification. Patients with certain nongastric tumors (2.1-5 cm and > 5 mitoses per 50 high-power fields or 5.1-10 cm and < or = 5 per 50 high-power fields) and those with tumor rupture are proposed to be included in the NIH high-risk category. High-risk patients defined by the proposed modified system have more than 15% to 20% risk of disease recurrence. The proposed system, if validated, may be useful in identifying which patients might potentially benefit from adjuvant therapy.

Gastrointestinal stromal tumor in Brazil: clinicopathology, immunohistochemistry, and molecular genetics of 513 cases

The aim of the present study was to evaluate the clinicopathological, immunohistochemical, and molecular genetic features of gastrointestinal stromal tumors in Brazil and compare them with cases from other countries. Five hundred and thirteen cases were retrospectively analyzed. HE-stained sections and clinical information were reviewed and the immunohistochemical expression of CD117, CD34, smooth-muscle actin, S-100 protein, desmin, CD44v3 adhesion molecule, p53 protein, epidermal growth factor receptor, and Ki-67 antigen was studied using tissue microarrays. Mutation analysis of KIT and platelet-derived growth factor receptor-alpha genes was also performed. There was a slight female predominance (50.3%) and the median age at diagnosis was 59 years. The tumors were mainly located in the stomach (38.4%). Immunohistochemistry showed that CD117 was expressed in 95.7% of cases. Epidermal growth factor receptor expression was observed in 84.4% of tumors. p53 protein expression was found only in 2.6% of cases but all belonged to the high-risk group for aggressive behavior according to the National Institutes of Health consensus approach. No CD44v3 adhesion molecule expression was detected. KIT exon 11 mutations were the most frequent (62.2%). The present data confirm that gastrointestinal stromal tumors in Brazilian patients do not differ from tumors occurring in other countries.

Tumor mitotic rate, size, and location independently predict recurrence after resection of primary gastrointestinal stromal tumor (GIST)

BACKGROUND

Gastrointestinal stromal tumor (GIST) is the most frequent sarcoma of the intestinal tract and often shows constitutive activation of either the KIT or PDGFRA receptor tyrosine kinases because of gain-of-function mutation. Although the efficacy of tyrosine kinase inhibitors in metastatic GIST depends on tumor mutation status, there have been conflicting reports on the prognostic importance of KIT mutation in primary GIST.

METHODS

A total of 127 patients were studied who presented to our institution from 1983 to 2002 with localized primary GIST and underwent complete gross surgical resection of disease. The majority of tumors originated in the stomach (58%) or small intestine (28%). By using polymerase chain reaction (PCR) and direct sequencing, a KIT mutation was found in 71% of patients and a PDGFRA mutation in 6%.

RESULTS

After a median follow-up of 4.7 years, recurrence-free survival was 83%, 75%, and 63% at 1, 2, and 5 years, respectively. On multivariate analysis recurrence was predicted by > or =5 mitoses/50 high-power fields, tumor size > or =10 cm, and tumor location (with patients having small bowel GIST doing the worst). In particular, a high mitotic rate conferred a hazard rate of 14.6 (95% confidence interval, 6.5-32.4). Specific KIT mutations had prognostic importance by univariate but not multivariate analysis. Patients with KIT exon 11 point mutations and insertions had a favorable prognosis. Those with KIT exon 9 mutations or KIT exon 11 deletions involving amino acid W557 and/or K558 had a higher rate of recurrence, whereas patients without a tyrosine kinase mutation had intermediate outcome.

CONCLUSIONS

In the absence of therapy with tyrosine kinase inhibitors, recurrence in completely resected primary GIST is independently predicted by mitotic rate, tumor size, and tumor location.

"Seedling" mesenchymal tumors (gastrointestinal stromal tumors and leiomyomas) are common incidental tumors of the esophagogastric junction

Gastrointestinal stromal tumors (GISTs) are the most common nonepithelial neoplasm of the gastrointestinal tract and show a predilection for the stomach. Most are detected because of symptoms, but some are incidental findings at autopsy or surgery for other reasons. Incidental GISTs tend to be smaller at diagnosis, but even small (<1 cm) GISTs have been shown to harbor activating KIT mutations at rates similar to advanced GISTs. However, the prevalence and characteristics of small GISTs in surgical resections of the esophagogastric junction (EGJ) remains unclear. We studied 150 esophagogastric resections for esophageal or EGJ carcinomas (100 with preoperative chemoradiation and 50 untreated cases) that had been extensively embedded for histologic examination (mean 30 sections/case). Number, size, morphology, and location of all GISTs and leiomyomas were recorded. All potential GISTs were evaluated with CD117 and CD34 immunohistochemistry, and a subset (35) leiomyomas with smooth muscle actin, desmin, and CD117. We found 18 incidental GISTs in 15 of 150 (10%) patients; 3 patients harbored 2 separate lesions. Prevalence of GIST was identical in treated (10 of 100) and untreated (5 of 50) cases. All (100%) showed positivity for both CD117 and CD34 and all were of spindle cell morphology. Lesions ranged from 0.2 to 3.0 mm in size (mean 1.3 mm). Eight (44%) were based in the outer muscularis propria, 7 (39%) in inner muscularis, and 3 (17%) between the muscle layers. The lesions tended to cluster near the EGJ, with 8 (44%) on the gastric side, 9 (50%) on the esophageal side, and 1 (6%) undetermined owing to overlying ulceration. Leiomyomas were even more common than GIST, occurring in 47% of patients (44% of treated and 52% of untreated, P=0.39), with a mean of 3 leiomyomas per patient (range 1 to 13) and mean size of 1.7 mm (range 0.2 to 12 mm). Unlike colorectal leiomyomas, most (91%) EGJ leiomyomas were located in the inner muscularis propria and only rarely (1%) in muscularis mucosa. These results suggest that GIST and leiomyoma are common incidental "seedling" lesions of the EGJ, found in 10% and 47% of patients undergoing surgery for esophageal carcinoma. The common occurrence of microscopic GISTs compared with the rarity of clinically manifest and malignant esophagogastric GISTs suggests that additional genetic or epigenetic alterations must happen for neoplastic progression.

The outcome of gastrointestinal stromal tumors (GISTs) after a surgical resection in our institute

PURPOSE

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract arising from Cajal's cells and expressing c-kit. In a consensus report, the clinical behavior of GISTs was categorized into risk classes according to the tumor size and mitotic count. We analyzed the risk categories based on GIST patients who underwent a surgical resection at our institute during a period of 15 years.

METHODS

We evaluated the risk categories of GISTs and analyzed the outcome and risk categories retrospectively. We presented the MIB-1 score of the tumor instead of mitotic counts for the evaluation of cellular growth because of inaccuracies regarding the mitotic counts.

RESULTS

Patients were classified into 4 cases of very low risk, 11 of low risk, 8 of intermediate risk, and 5 of high risk. Four high-risk patients showed recurrence as either liver metastasis or peritoneal dissemination. In addition, local recurrence occurred in one low-risk and one intermediate-risk patient each.

CONCLUSION

Our cases confirmed the correlation between the risk categories and the prognosis. A complete resection with sufficient margin must be confirmed even in low-risk cases to prevent local recurrence. Since high-risk patients showed poor prognosis, the adjuvant treatment with chemotherapeutic regimens must therefore be further studied for high-risk patients.

Spectrum and prognostication of KIT and PDGFRA mutation in gastrointestinal stromal tumors

AIMS

Recent studies reported various mutation rates in gastrointestinal stromal tumors (GISTs) and inconsistent prognostic value of mutation in GIST patients. Our purpose was to analyze the frequency and spectrum of KIT and PDFGRA in a large series study and to determine if the presence of mutation and mutation type serve as prognostic factors in GIST patients.

METHODS

A total of 134 GISTs were subjected to mutation analysis of KIT (exons 9, 11, 13, and 17) and PDGFRA (exons 10, 12, 14, and 18). Clinicopathologic characteristics and survivals were correlated to KIT mutation.

RESULTS

Approximately 69% of GISTs had KIT/PDGFRA mutation in Taiwanese GIST patients, with 99% of mutations occurred in KIT and 1% occurred in PDGFRA. Mutation rate was significantly increased in GISTs with mitotic counts >5 per 50 high power fields (chi(2) test, p=0.045). However, KIT mutations, regardless of the location (exons 9 versus 11) and type (missense, insertion, and deletion, including deletion specifically involving codons 557 and 558) of mutation, were not significantly associated with poor progression-free survivals. Comparing the overall survival in imatinib-treated patients, there was no significant difference between patients with exon 11 mutation and those with exon 9 mutation (p=0.473).

CONCLUSIONS

GISTs were commonly associated with KIT mutation, but rarely associated with PDGFRA mutation in Taiwan. The presence of KIT mutation and mutation type was not significant prognostic factors in GIST patients without imatinib treatment, suggesting that there is no need to stratify GIST patients by mutation status in clinical trials of targeted therapy.

KIT and PDGFRA mutations in gastrointestinal stromal tumors (GISTs)

Mutually exclusive KIT and PDGFRA mutations are central events in GIST pathogenesis, and their understanding is becoming increasingly important, because specific treatment targeting oncogenic KIT and PDGFRA activation (especially imatinib mesylate) has become available. KIT mutations in GIST are clustered in four exons. Most common are exon 11 (juxtamembrane domain) mutations that include deletions, point mutations (affecting a few codons), and duplications (mostly in the 3' region). The latter mutations most often occur in gastric GISTs. Among gastric GISTs, tumors with deletions are more aggressive than those with point mutations; this does not seem to hold true in small intestinal GISTs. Exon 9 mutations (5-10%) usually are 2-codon 502-503 duplications, and these occur predominantly in intestinal versus gastric GISTs. Lesser imatinib sensitivity of these tumors has been noted. Kinase domain mutations are very rare; GISTs with such mutations are variably sensitive to imatinib. PDGFRA mutations usually occur in gastric GISTs, especially in the epithelioid variants; their overall frequency is approximately 30% to 40% of KIT mutation negative GISTs. Most common is exon 18 mutation leading Asp842Val at the protein level. This mutation causes imatinib resistance. Exon 12 and 14 mutations are rare. Most mutations are somatic (in tumor tissue only), but patients with familial GIST syndrome have consitutitonal KIT/PDGFRA mutations; >10 families have been reported worldwide with mutations generally similar to those in sporadic GISTs. GISTs in neurofibromatosis 1 patients, children, and Carney triad seem to lack GIST-specific KIT and PDGFRA mutations and may have a different disease mechanism. Secondary mutations usually occur in KIT kinase domains in patients after imatinib treatment resulting in resistance to this drug. Mutation genotyping is a tool in GIST diagnosis and in assessment of sensitivity to kinase inhibitors. This is a US government work. There are no restrictions on its use.

KIT-negative gastrointestinal stromal tumors with a long term follow-up: A new subgroup does exist

AIM: To investigate the incidence of KIT immunoho-stochemical staining in (GI) stromal tumors (GISTs), and to analyze the clinical manifestations of the tumors and prognostic indicators.

METHODS: We retrospectively analyzed 50 cases of previously diagnosed GISTs. Tissue samples were assessed with KIT (CD117 antigen), CD34, SMA, desmin, S-100, NSE, PCNA, Ki-67, and BCL-2 for immunohistochemical study and pathological characteristics were analyzed for prognostic factors.

RESULTS: Fifteen tumors (30%) were negative in KIT staining. A significant association was observed between gender (male patients: 14/15) and KIT-negative staining (P = 0.003).The patients's mean age was 56.6 years. Tumors developed in stomach (n = 8), small intestine (n = 5), large intestine (n = 1) and oesophagus (n = 1). The mean tumor size was 5.72 cm. The mitotic count ranged from 0-29/50 HPF (mean: 3.4) and 73% of tumors showed no necrosis. The majority of the tumors (67%) had dual or epithelioid differentiation. Tumors were classified as very low or low risk (n = 7), intermediate risk (n = 5), and high risk (n = 3) groups. Twelve (80%) patients were alive without evidence of residual tumor for an average period of 40.25 mo (12-82 mo); three patients developed metastatic disease to the liver and eventually died within 2-12 mo (median survival: 8.6 mo).

CONCLUSION: A small subgroup of GISTs fulfils the clinical and morphological criteria of these tumors, and lacks KIT expression. These tumors predominantly developed in the stomach, being dual or epithelioid in morphology, which are classified as low risk tumors and presented a better survival status than KIT-positive tumors. The ability to diagnose GISTs still depends on immunohistochemical staining but the research should extend in gene mutations.

Tissue microarrays characterise the clinical significance of a VEGF-A protein expression signature in gastrointestinal stromal tumours

A tissue microarray analysis of 22 proteins in gastrointestinal stromal tumours (GIST), followed by an unsupervised, hierarchical monothetic cluster statistical analysis of the results, allowed us to detect a vascular endothelial growth factor (VEGF) protein overexpression signature discriminator of prognosis in GIST, and discover novel VEGF-A DNA variants that may have functional significance.

Outcome of Metastatic GIST in the Era before Tyrosine Kinase Inhibitors

BACKGROUND

Treatment of metastatic GIST with imatinib mesylate results in a 2-year survival of approximately 72%. The outcome of patients with metastatic GIST not treated with tyrosine kinase inhibitors is not well defined.

METHODS

One hundred nineteen patients with metastatic GIST diagnosed prior to July 1, 1998 (approximately 2 years prior to the use of imatinib for GIST) were identified from an institutional database of patients with pathologically confirmed GIST. Mutational analysis was performed in cases with available tissue. The log rank test and Cox regression models were used to assess prognostic factors.

RESULTS

Median survival was 19 months with a 41% 2-year survival and a 25% 5-year survival. Resection of metastatic GIST was performed in 81 patients (68%), while 50 (42%) received conventional chemotherapy. Twelve patients (10%) were eventually started on imatinib. Primary tumor size <10 cm, <5 mitoses/50 HPF in the primary tumor, epithelioid morphology, longer disease-free interval, and surgical resection were independent predictors of improved survival on multivariate analysis. Mutational status did not predict outcome. In patients who underwent resection, the 2 year survival was 53%, and negative microscopic margins also independently predicted improved survival.

CONCLUSIONS

Treatment with imatinib appears to improve 2-year survival of metastatic GIST by approximately 20% when compared to surgery alone. The combination of imatinib and surgery for the treatment of metastatic GIST therefore warrants investigation.

Prognostic factors affecting survival after surgical resection of gastrointestinal stromal tumours: a two-unit experience over 10 years

BACKGROUND

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal neoplasm of the gastrointestinal (GI) tract which has only been recently described based on their specific immunohistochemistry and the presence of particular KIT-related mutations which potentially make them targets for tyrosine kinase inhibition.

METHODS

Sixty-one patients (29 M; 32 F, median age 60 years; range: 23-86 years) between June 1994 and March 2005, were analyzed from two allied institutions. Patient, tumour, and treatment variables were analyzed to identify factors affecting survival.

RESULTS

Of the 61 patients, 55 (90%) underwent complete surgical resection of macroscopic disease. The 5-year overall survival (OS) rate in the 61 patients was 88% and the 5-year disease-free survival (DFS) in the 55 cases completely resected was 75%. Univariate analysis revealed that R0 resection was strongly associated with a better OSrate (p < 0.0001). Likewise, univariate analysis also showed high mitotic count of > 10 mitoses/per 50 HPF was a significant variable in worse prognosis for OS (<or= 10 mitoses/per 50 HPF 95% 5-year OS vs. > 10 mitoses/per 50 HPF 74% 5-year OS, respectively; p = 0.013). On subsequent multivariate analysis, only high mitotic count remained as a significant negative prognostic variable for OS (p = 0.029). Among patients resected for cure, there were 8 recurrences during follow-up. The mean time to recurrence was 21 +/- 10 months (range: 4-36 months). Univariate analysis revealed that mitotic count of > 10 mitoses per 50 high power fields, intratumoural necrosis, and pathological tumour size (> 10 cm in maximal diameter) significantly correlated with DFS (p = 0.006, 0.002 and 0.02, respectively), with tumour necrosis and high mitotic count remaining as independent predictive variables affecting prognosis on subsequent multivariate analysis.

CONCLUSION

Most GISTs are resectable with survival principally dependent upon mitotic count and completeness of resection. Future metabolic and genetic analyses will define the role of and resistance to induction or postoperative adjuvant targeted kinase inhibition therapy.

Detection of c-kit exons 11- and 17-activating mutations in testicular seminomas by high-resolution melting amplicon analysis

A subgroup of testicular seminomas has been reported to contain activating mutations in KIT, the transmembrane tyrosine kinase receptor encoded by the c-kit gene. Most mutations are in exon 17, although exon 11-activating mutations have recently been described. For patients refractory to standard therapeutic protocols for seminoma, the presence of c-kit-activating mutations in some of these neoplasms might suggest an alternative therapy with KIT targeting drugs. We used the novel mutation scanning technique, high-resolution melting amplicon analysis, to screen a series of 22 testicular seminomas for c-kit-activating mutations. Four cases (18%) had exon 17-activating mutations and these included D816Y, D816V, Y823N and one case that contained both D816E and D820H. A single case (5%) had an exon 11-activating mutation. Interestingly, the exon 11-activating mutation was L576P, the same mutation that characterizes the rare c-kit mutation-positive cases of malignant melanoma. Fluorescence in situ hybridization (FISH) for c-kit suggested that most seminomas are probably polysomic for c-kit and there was not a significant difference in c-kit FISH characteristics between the mutation-positive and mutation-negative cases. The use of high-resolution melting amplicon analysis as a screening technique will allow for the rapid identification of patients with testicular seminomas whose tumors contain c-kit-activating mutations. This could benefit patients whose tumors are refractory to standard therapeutic protocols.

Expression of Bcl-2 in gastrointestinal stromal tumors: correlation with progression-free survival in 81 patients treated with imatinib mesylate

BACKGROUND

The natural history of gastrointestinal stromal tumor (GIST) has been revolutionized by imatinib mesylate (imatinib) therapy. Before imatinib, Bcl-2 expression in GIST was associated with a worse prognosis or added no additional prognostic value. To the authors' knowledge, the current study is the first to evaluate Bcl-2 expression in pre-imatinib GIST tissue samples as a prognostic marker of progression-free survival (PFS) time in patients treated with imatinib.

METHODS

The cases of 81 patients with GIST who were evaluated between December 15, 2000 and September 1, 2001 were retrospectively reviewed. Clinicopathologic variables were reviewed. GIST cell morphology and patterns of Bcl-2 expression were described. The methods of Kaplan-Meier and the Cox proportional hazards regression model were used for statistical analysis.

RESULTS

Sixty-one (75%) patients had tumors that expressed Bcl-2, and 20 (25%) patients had tumors that were negative for Bcl-2. All epithelioid tumors (n = 12) expressed Bcl-2 and tumors with mixed morphology exhibited Bcl-2 expression in the epithelioid component. A trend toward longer PFS for patients whose tumors expressed Bcl-2 at a greater immunohistochemical intensity was observed (20.6 mos for no Bcl-2 expression; 28.3 mos for 1++Bcl-2 expression; 31.9 mos for 1.5++Bcl-2 expression; 40.8 mos for 2++Bcl-2 expresssion; and 35.9 mos for 3++Bcl-2 expression).

CONCLUSIONS

In contrast to studies performed in the preimatinib era, in which Bcl-2 was found to be a negative prognostic indicator, the current study suggests a trend toward better PFS with increasing Bcl-2 expression level in GISTs from patients subsequently treated with imatinib. Larger studies may help elucidate the influence of Bcl-2 expression on PFS after therapy with imatinib.