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Purpose: Although the mutational status in gastrointestinal stromal tumors (GIST) can predict the response to treatment with tyrosine kinase inhibitors, the role of tumor genotype as a prognostic factor remains controversial. The ConticaGIST study sought to determine the pathologic and molecular factors associated with disease-free survival (DFS) in patients with operable, imatinib-naive GIST., Experimental Design: Clinicopathologic and molecular data from 1,056 patients with localized GIST who underwent surgery with curative intention (R0/R1) and were registered in the European ConticaGIST database were prospectively obtained and reviewed. Risk of tumor recurrence was stratified using the modified NIH criteria. The median follow-up was 52 months., Results: On testing for potential prognostic parameters, the following were associated with inferior DFS on multivariable Cox model analysis: primary nongastric site, size >10 cm, mitotic index >10 mitoses per 50 high power field, and the KIT exon 9 duplication [hazard ratio (HR), 1.47; 95% confidence interval (CI), 0.9-2.5; P = 0.037] and KIT exon 11 deletions involving codons 557 and/or 558 [KITdel-inc557/558; HR, 1.45; 95% CI, 1.0-2.2; P = 0.004]. Conversely, PDGFRA exon 18 mutations were indicators of better prognosis [HR, 0.23; 95% CI, 0.1-0.6; P = 0.002]. KITdel-inc557/558 were an adverse indicator only in GIST localized in the stomach (P < 0.001) but not in tumors with nongastric origin. In gastric GIST, all other mutations presented remarkably superior 5-year DFS., Conclusions: In conclusion, tumor genotype is an independent molecular prognostic variable associated with gastric GIST and should be used for optimizing tailored adjuvant imatinib treatment., (©2014 American Association for Cancer Research.)

Unlabelled: GIST is the most common mesenchymal tumour of gastrointestinal tract arising from mutation of KIT or PDGFRA gene. Surgery is the primary method of treatment, however a targeted therapy with imatinib is necessary due to recurrence. The aim of the study was to evaluate efficacy of the targeted chemotherapy in advanced gastrointestinal stromal tumours with non-exon 11 KIT mutations., Material and Methods: Data from 279 patients with advanced GIST treated with imatinib between 2001 and 2011 were analysed in the study. Exon 11 KIT mutation was found in 192 patients (68.7%), non-exon 11 KIT mutation was found in 87 patients (31.3%): this group included lack of mutation - wild-type, exon 9 KIT mutations, exon 18 PDGFRA D842V mutations, non-D842V PDGFRA mutations as well as non-exon 9 and 11 KIT mutations. Analysis of progression-free survival and overall survival were done for the entire group of patients and for patients with particular mutations, and then effects on progression-free survival and overall survival of such factors as sex, age, imatinib dose were evaluated., Results: Occurrence of non-exon 11 KIT mutation increases the risk of disease progression by 20% in comparison to the presence of exon 11 KIT mutation, however it does not increase the risk of patient's death. Percentage of 5-year progression-free survivals is the greatest in the case of PDGFRA mutation other than D842V mutation. Percentage of 5-year survivals in case of the presence of D842V PDGFRA mutation is more than twice worse than in the case of the other mutations. Lesion location in the gastrointestinal tract affected the risk of death, with the greatest percentage of 5-year survival for lesions located in the stomach. Such factors as sex, age at diagnosis (<50, ≥50 years) and imatinib dose did not affect the risk of disease progression and the risk of patient's death., Conclusions: The ratio of overall survival of patients with advanced GIST with a mutation other than exon 11 KIT mutation treated with imatinib is similar to the ratio of overall survival of patients with GIST with exon 11 KIT mutation. An exception is the group of patients with GIST in whom the presence of D842V PDGFRA mutation was found. In general, longer survival has been found in patients with GIST located in the stomach in comparison to the small intestine or other less frequent locations. Percentage of 5-year progression-free survivals is the greatest in the case of PDGFRA mutation other than D842V mutation.

The introduction of imatinib to clinical practice revolutionized therapy of advanced gastrointestinal stromal tumors (GIST), but its long-term results have been only just collected. We have attempted to identify factors related to the long-term survival. We have analyzed the data of 430 inoperable/metastatic/recurrent GIST patients treated with imatinib in reference centers, assessed the factors influencing the long-term overall survival (OS), and compared the outcomes in three periods of initiation of imatinib therapy during one decade (2001-2003, 2004-2006, 2007-2010). During analyzed time periods, we have found decrease in median largest tumor size at the start of imatinib therapy: 90.5 mm (2001-2003) versus 74 mm (2004-2006) versus 58 mm (2007-2010) (p = 0.002). Median progression-free survival (PFS) on 1st line imatinib was 37.5 months, without differences in PFS between three groups. Median OS was 5.8 years, 8-year OS rate was 43%, and no difference in OS was demonstrated for patients treated in analyzed time periods. Independent good prognostic factors for longer OS were as follows: surgery of residual disease, initial WHO performance status 0/1, normal baseline albumin level, and the presence of exon 11 KIT mutations. Current median OS in advanced GIST reaches 6 years. The long-term survivors were characterized by smaller maximal tumors at imatinib start, better blood tests results, better performance status, and the surgical removal of residual disease. The latter might reduce the impact of tumor size and equalize the long-term results of therapy during last decade from introduction of imatinib. After introduction of subsequent lines of therapy (as sunitinib), the effect of primary mutational status on the long-term OS is also less visible.

Background: Gastrointestinal stromal tumors (GIST) mutational status is recognized factor related to the results of tyrosine kinase inhibitors therapy such as imatinib (IM) or sunitinib (SU). Arterial hypertension (AH) is common adverse event related to SU, reported as predictive factor in renal cell carcinoma. The aim of the study was to analyze the outcomes and factors predicting results of SU therapy in inoperable/metastatic CD117(+) GIST patients after IM failure., Methods: We identified 137 consecutive patients with advanced inoperable/metastatic GIST treated in one center with SU (2nd line treatment). Median follow-up time was 23 months. Additionally, in 39 patients there were analyzed selected constitutive single nucleotide polymorphisms (SNPs) of VEGFA and VEGFR2 genes., Results: One year progression-free survival (PFS; calculated from the start of SU) rate was 42% and median PFS was 43 weeks. The estimated overall survival (OS, calculated both from start of SU or IM) was 74 weeks and 51 months, respectively. One-year PFS was 65% (median 74 weeks) in 55 patients with AH vs. 22% (median 17 weeks) in patients without AH. Patients with primary tumors carrying mutations in KIT exon 9 or wild-type had substantially better 1-year PFS (68% and 57%; median 65.5 and 50.5 weeks, respectively) than patients having tumors with KIT exon 11 or PDGFRA mutations (34% and 15%; median 36.8 and 9 weeks, respectively). We identified two independent factors with significant impact on PFS and OS in univariate and multivariate analysis: primary tumor genotype and presence of AH. The most common adverse events during therapy were: fatigue, AH, hypothyroidism, hand and foot syndrome, mucositis, skin reactions, dyspepsia, and diarrhea. Two deaths were assessed as related to tumor rupture caused by reaction to SU therapy. The presence of C-allele in rs833061 and the T-allele in rs3025039 polymorphism of VEGFA were associated with significantly higher risk of hypothyroidism (OR: 10.0 p = 0.041 and OR: 10.5; p = 0.015, respectively)., Conclusions: We confirmed that many advanced GIST patients benefit from SU therapy with OS > 1.5 year. Primary tumor KIT/PDGFRA genotype and SU-induced AH, as surrogate of its antiangiogenic activity are two independent factors influencing both PFS and OS.

Background: The objectives of the current study were to assess the reliability of the new revision of the American Joint Committee on Cancer (AJCC) staging system for gastrointestinal stromal tumors (GISTs) based on the National Comprehensive Cancer Network-Armed Forces Institute of Pathology risk classification and to analyze the factors that influence after resection for primary GISTs in 2 AJCC groups: patients with GISTs originating from the stomach and omentum (G-GISTs) and patients with other primary GISTs located mainly in the small bowel (nongastric GISTs [NG-GISTs])., Methods: The authors prospectively analyzed a group of 640 patients with primary, CD117-positive GISTs who underwent surgery with curative intention (R0/R1 resection), including 340 G-GISTs (55.5%) and 300 NG-GISTs (44.5%). Factors were explored that had an effect on disease-free survival time (DFS), which was calculated from the date of radical operation to the date of recurrence or last follow-up. The median follow-up was 39 months., Results: Compared with NG-GISTs, G-GISTs were characterized by a significantly lower median size (5.3 cm and 8.5 cm, respectively; P < .0001) and lower mitotic activity (median, 3 in 50 high-power fields [HPF] vs 5 in 50 HPF; P < .0001), and they were diagnosed in older patients (median age, 62 years vs 57 years; P = .002). The most commonly detected mutations in G-GIST were those located in KIT exon 11 (60.5%) and platelet-derived growth factor receptor alpha (PDGFRA) exon 18 (19%) versus KIT exons 11 and 9 in NG-GISTs (72% and 17.4%, respectively). The prognosis of patients who had G-GISTs was significantly better compared that of patients who had NG-GISTs, with 5-year DFS rates of 69% (median, 83 months) versus 43% (median, 33 months), respectively (P < .00001). The most significant prognostic factors that correlated with shorter DFS in both G-GISTs and NG-GISTs were primary tumor size >5 cm and >10 cm (P < .0001) and mitotic index >5 in 50 HPF and >10 in 50 HPF (P < .0001). The 5-year DFS rates in G-GISTs according to AJCC stage categories were as follows: 96% for stage IA tumors, 92% for stage IB tumors, 51% for II tumors, 22% for stage IIIA tumors, and 22% for stage IIIB tumors (P < .0001). The 5-year DFS rates in NG-GISTs according to AJCC categories were as follows: 92% for stage I tumors, 66% for stage II tumors, 28% for IIIA tumors, and 16% for IIIB tumors (P < .0001). The high prognostic significance of the AJCC classification also was confirmed for overall survival data, including the impact of therapy with tyrosine kinase inhibitors., Conclusions: The reliability of AJCC risk classification after resection of primary GIST was confirmed for DFS and overall survival. Patients with primary G-GISTs had a better prognosis than patients with NG-GISTs. In both groups, primary tumor size and mitotic activity were the most important prognostic factors in terms of DFS., (Copyright © 2011 American Cancer Society.)

Background: The development of accurate diagnostic methods in gastrointestinal stromal tumors (GISTs) and the introduction of imatinib (IM) therapy has focused attention on the factors influencing the prognosis of patients with primary lesions as well as of patients with advanced disease treated with imatinib., Material/methods: The clinico-pathological and genetic factors influencing disease-free survival (DFS) in 335 patients with primary CD117-immunopositive tumors (group A; calculated from primary tumor resection) and progression-free survival (PFS) in 232 metastatic/unresectable GIST patients treated with IM (group B; calculated from the start of imatinib therapy) were analyzed., Results: In group A, statistically significant factors negatively influencing DFS(five-year DFS: 38%), both in univariate and multivariate analysis, were: primary tumor size >5 cm, mitotic index >5/50 HPF (high-power fields), male gender, primary tumor R1 resection or tumor rupture, non-gastric primary tumor localization. In group B, five factors negatively affecting PFS (three-year PFS: 54%) were identified, which were statistically significant both in univariate and multivariate analyses: WHO performance status >/=2, tumor genotype indicating other than exon 11 KIT mutation, high baseline pre-IM granulocyte count, mitotic index >10/50 HPF, and age <45 years at diagnosis., Conclusions: Different sets of independent biological and pathological prognostic factors were identified for the assessment of the natural course of primary GIST and for the prediction of PFS during IM therapy for advanced GIST.

The Purpose: To analyze the outcomes of treatment and factors predicting effects of imatinib (IM) therapy in inoperable/metastatic gastrointestinal stromal tumors (GIST) CD117(+) patients., Materials and Methods: We identified 232 patients in a prospectively collected Clinical GIST Registry with advanced inoperable/metastatic GIST treated with IM 400-800 mg daily (129 males and 103 females and median age 56 years). Median follow-up time was 26 months., Results: The estimated 3-year progression-free survival (PFS; calculated from the date of the start of IM) was 54% and median PFS was 40.5 months. The following factors significantly and negatively influenced PFS in univariate analysis: poor baseline World Health Organization (WHO) performance status > or = 2 (P < 0.00001), tumor genotype indicating other than KIT exon 11 isoform (P = 0.005), baseline high neutrophils count (P < 0.00001), age <45 years at the diagnosis (P = 0.04), mitotic index >10/50 high-power fields (HPF) (P = 0.001), GIST histological type other than spindle-cell (P = 0.03), baseline low albumin level (P = 0.0005), low baseline hemoglobin level (P < 0.00001), and primary overtly malignant tumors (unresectable and/or metastatic lesions at presentation) (P = 0.05). We identified four factors negatively affecting PFS, statistically significant (P < 0.05) in multivariate analysis: baseline poor WHO performance status > or = 2, high baseline neutrophils count (>5 x 10(9)/l), tumor genotype indicating the presence of non-exon 11 KIT mutant and mitotic index >10/50 HPF., Conclusions: We confirmed that many advanced GIST patients benefit from IM therapy for a prolonged time, although resistance to therapy is observed. We identified four independent biological factors influencing the PFS during long-term IM therapy.

Background: The introduction of adjuvant imatinib in gastrointestinal stromal tumors (GISTs) raised debate over the accuracy of National Institutes of Health risk criteria and the significance of other prognostic factors in GIST., Methods: Tumor aggressiveness and other clinicopathological factors influencing disease-free survival (DFS) were assessed in 335 patients with primary resectable CD117-immunopositive GISTs (median follow-up, 31 months after primary tumor resection) from a prospectively collected tumor registry., Results: Overall median DFS was 37 months, and estimated 5-year DFS was 37.8 %. In univariate analysis, high or intermediate risk group (P < .000001), mitotic index >5/50 high-power field (P < .00001), primary tumor size >5 cm (P < .00001), nongastric primary location (P = .0001), male sex (P = .01), R1 resection/tumor rupture (P = .0003), and epithelioid cell or mixed cell pathological subtype (P = .05) negatively affected DFS. In multivariate analysis, statistically significant factors negatively influencing DFS for model 1 were mitotic index >5/50 high-power field (P = .004), primary tumor size >5 cm (P = .001), male sex (P = .003), R1 resection/tumor rupture (P = .04), and nongastric primary tumor location (P = .02), and for model 2 were high/intermediate risk primary tumor (P < .0001 and P = .008, respectively), male sex (P = .007), resection R1/tumor rupture (P = .01), and nongastric primary tumor location (P = .02). Five-year DFS for high, intermediate, and low/very low risk group was 20%, 54%, and 96%, respectively., Conclusions: The risk criteria for assessing the natural course of primary GISTs were validated, but additional independent prognostic factors-primary tumor location and sex--were also identified.

Gastrointestinal stromal tumors (GISTs) comprise a biologically diverse group of neoplasms with respect to activating mutations in either KIT or PDGFRA, histology, anatomical site of origin, and clinical aggressiveness. In this study, we applied the high resolution array-based comparative genomic hybridization (array-CGH) technology to 66 primary GISTs (40 gastric and 26 nongastric, 48 with KIT and 18 with PDGFRA mutations) for identification of novel high-level alterations and for characterization of genotype-related genomic changes. All cases had genomic imbalances with the highest occurrence of 14q (73%), 1p (62%), 22q (59%), 15q (38%), and 13q (29%) losses. Our data indicate that loss of chromosome 14 and/or 22 is an early change in GIST tumorigenesis irrespective of tumor genotype. Furthermore, DNA copy number changes showed a site dependent pattern. These included lower incidence of losses at 14q (87% vs. 35%), and higher frequency of losses at 1p (45% vs. 85%) and 15q (17% vs. 69%) in nongastric versus gastric site (P<0.001 for all). However, in the multivariate analysis with adjustment to tumor risk stratification, only the 14q loss site-dependent pattern of distribution retained its significance. These findings suggest that loss of 14q is a relatively less frequent genetic event in the development of nongastric GISTs, the lack of which is most likely substituted by the accumulation of 1p/15q and other changes. The novel minimal overlapping regions of deletion at 1p (1p36.32-1p35.2, 1p34.1, and 1p22.1-1p21.3), 13q (13q14.11-q14.2 and 13q32.3-q33.1), and 15q23 were delineated, which point to chromosomal regions that may harbor genes relevant to the development of these neoplasms., (Copyright (c) 2006 Wiley-Liss, Inc.)

Gastrointestinal stromal tumors (GISTs) are the most common gastrointestinal mesenchymal tumors driven by KIT or PDGFRA mutations. A majority of these mutations affect KIT exon 11 and represent deletions or point mutations, but insertions and duplications have also been reported. The latter have been found exclusively in the 3' part of KIT exon 11. Reported frequency of duplications varies, and a higher frequency has been reported in studies based on frozen tissue. Recently, we have hypothesized that in some cases, the duplications might remain undetected in formalin-fixed, paraffin-embedded GISTs because of the preferential polymerase chain reaction (PCR) amplification of wild-type KIT over the mutant allele. In this study, 16 GISTs initially diagnosed as a wild-type KIT were evaluated using PCR assay amplifying only the 3' part of KIT exon 11, the region commonly affected by duplications. Denaturing high-pressure liquid chromatography and direct sequencing analyses revealed duplications in 4 (25%) of 16 analyzed cases. Use of the PCR assay amplifying the specific region affected by duplications and yielding 129 bp in wild-type KIT can substantially improve the detection of these mutations in formalin-fixed, paraffin-embedded GISTs.

Mutational activation of KIT or PDGFRA is considered an early step in pathogenesis of gastrointestinal stromal tumors (GISTs); however, other nonrandom genetic changes have also been identified. At least three common regions of deletions on chromosome 22q, which may harbor putative tumor suppressor genes, have been defined. However, mapping of these regions has been inconsistent. It has also been speculated that GI autonomous nerve tumors (GANTs), GISTs with ultrastructural features suggestive of autonomic nerve differentiation, are characterized by a specific deletion involving 22q13 cytogenetic region. This study was undertaken to evaluate loss of heterozygosity (LOH) on chromosome 22q in 50 GISTs, including 10 GANTs. Four tumors were incidental minimal lesions

The report presents 200 cases of gastrointestinal stromal tumors (GIST). The material originated from six diagnostic centers in Poland and was reclassified according to the current criteria. Among lesions other than GISTs, 14 were identified as smooth muscle tumors and seven as neural tumors. GISTs were located in the stomach (51-63.3% of the investigated series), small intestine (27.4-33.8%), colon (approximately 4.5%), abdominal cavity, i.e. in the peritoneum and omentum (6%), and in the retroperitoneal space (2.5%). A slight predominance of women was noted (53-56%). The age of the patients ranged between 14 and 93 years of life, with the mean age of 62.4 years. Individuals younger than 45 years of age accounted for 10% of the group. In ten patients (five of them less than 45 years of life), multiple tumors were detected, their number ranging from two to less than 20; these individuals constituted 5% of the entire series. Moderately and highly aggressive tumors predominated. In the series, when multiple tumors were excluded, a total of 24 epithelioid GISTs (12%) were observed; of this number, 13 were situated in the stomach, six--in the small intestine, two--in the abdominal cavity and another two in the retroperitoneal space. Synchronic tumors observed in patients with GISTs were seen in seven patients, including an adenocarcinoma of the colon, two adenocarcinomas of the stomach, a carcinoid tumor of the small intestine, a pheochromocytoma of the retroperitoneal space, an anaplastic lymphoma and a disseminated squamous cell carcinoma. In immunohistochemical reactions (CD117, CD34, SMA, S-100, DES), attention was focused on the immunoreactivity of small GISTs, below 2 cm in size, and of multiple tumors. Immunohistochemical reactions were equally differentiated as to their presence and intensity in small tumors and in highly aggressive lesions above 5-10 cm in size. In multiple GISTs, immunohistochemical tests strongly indicated the heterogeneity of neoplastic cells, which, nevertheless, showed no consistent association with the location of the tumor, its aggressiveness, cellular structure or a tendency to form multiple foci.

GIST is the most common mesenchymal tumour of gastrointestinal tract arising from mutation of KIT or PDGFRA gene. Surgery is the primary method of treatment, however a targeted therapy with imatinib is necessary due to recurrence. The aim of the study was to evaluate efficacy of the targeted chemotherapy in advanced gastrointestinal stromal tumours with non-exon 11 KIT mutations. Material and methods. Data from 279 patients with advanced GIST treated with imatinib between 2001 and 2011 were analysed in the study. Exon 11 KIT mutation was found in 192 patients (68.7%), non-exon 11 KIT mutation was found in 87 patients (31.3%): this group included lack of mutation - wild-type, exon 9 KIT mutations, exon 18 PDGFRA D842V mutations, non-D842V PDGFRA mutations as well as non-exon 9 and 11 KIT mutations. Analysis of progression-free survival and overall survival were done for the entire group of patients and for patients with particular mutations, and then effects on progression-free survival and overall survival of such factors as sex, age, imatinib dose were evaluated. Results. Occurrence of non-exon 11 KIT mutation increases the risk of disease progression by 20% in comparison to the presence of exon 11 KIT mutation, however it does not increase the risk of patient's death. Percentage of 5-year progression-free survivals is the greatest in the case of PDGFRA mutation other than D842V mutation. Percentage of 5-year survivals in case of the presence of D842V PDGFRA mutation is more than twice worse than in the case of the other mutations. Lesion location in the gastrointestinal tract affected the risk of death, with the greatest percentage of 5-year survival for lesions located in the stomach. Such factors as sex, age at diagnosis (<50, ≥50 years) and imatinib dose did not affect the risk of disease progression and the risk of patient's death. Conclusions. The ratio of overall survival of patients with advanced GIST with a mutation other than exon 11 KIT mutation treated with imatinib is similar to the ratio of overall survival of patients with GIST with exon 11 KIT mutation. An exception is the group of patients with GIST in whom the presence of D842V PDGFRA mutation was found. In general, longer survival has been found in patients with GIST located in the stomach in comparison to the small intestine or other less frequent locations. Percentage of 5-year progression-free survivals is the greatest in the case of PDGFRA mutation other than D842V mutation. [ABSTRACT FROM AUTHOR]