Epidemiology and molecular biology of gastrointestinal stromal tumors (GISTs): a population-based study in the South of Switzerland, 1999-2005

Association Between Gastrointestinal Stromal Tumors and Other Malignancies: It Is Only a Matter of Time ? A Case Series and an Overview of Systematic Reviews

PURPOSE

Little is known about the sporadic coincidence of gastrointestinal stromal tumors (GISTs) with second primary tumors (SPTs). The aim of this study is to clarify if there is a clinicopathologic correlation responsible for the synchronous or metachronous occurrence of SPTs in GIST patients.

METHODS

We carried out a single-center, retrospective analysis on patients with GISTs surgically treated at our institution from January 2019 to June 2019. Two groups of patients were identified: isolated GIST (group A) and GIST associated with SPT (group B). A meta-review was conducted with the aim to examine the published systematic reviews that included studies assessing the SPT risk in GIST patients.

RESULTS

Thirty-nine patients were surgically treated for GIST during the study period, with seven (17.9%) of them having other SPTs. SPTs were most frequent in the colon. Group A patients had a lower mean age at initial diagnosis (56.8 ± 15.2 vs. 73.4 ± 16.6, P = 0.012). No statistically significant difference was found between the two groups in terms of tumor location, mitotic index, Ki-67 expression, risk classification, and imatinib therapy. The overview showed that the cumulative prevalence rate of SPTs ranged from 9.3 to 18.0%. SPTs were more frequent in the gastrointestinal tract (37.9-95.0%), followed by the genitourinary tract.

CONCLUSION

GIST patients under our care experienced a 17.9% overall risk of developing SPTs with different histology. When comparing patients with isolated GIST and patients with GIST and SPT, age was the only variable significantly related to the development of other neoplasms. However, the potential non-random association and causal relationship between GISTs and SPTs remain to be investigated.

The association of renal cell carcinoma with gastrointestinal stromal tumors

BACKGROUND AND OBJECTIVES

Prior small studies have reported a possible association between renal cell carcinoma (RCC) and gastrointestinal stromal tumors (GISTs). In the largest known series, our objective was to describe the prevalence of RCC among patients with GISTs over 26 years at Memorial Sloan Kettering Cancer Center (MSKCC).

METHODS

We retrospectively reviewed MSKCC's prospectively maintained sarcoma and RCC databases and identified all patients with both RCC and GIST between 1980 and 2016. Demographic and clinicopathological characteristics were obtained.

RESULTS

A total of 9/405 (2.2%) GIST patients were identified with RCC, with a mean follow-up of 9.2 (range 3.8-28.4) years. Five out of nine (55.6%) patients had RCC and GIST diagnosis within 6 months of each other. Mean RCC tumor size was 3.0 (range 1.8-8) cm and 8/9 (88.9%) patients were RCC stage 1. A total of 4/9 (44.4%) patients had papillary RCC (pRCC) histology, 5/9 (55.6%) had additional alternative malignancies, and 4/9 (44.4%) had primary small bowel GIST.

CONCLUSIONS

Our series suggests a possible association of RCC with GISTs. In addition, we found a high frequency of pRCC histology, alternative malignancies, and small bowel GISTs in co-occurring RCC-GIST patients. Further investigation to identify genetic mutations, in this population, would assist in surveillance and treatment.

Comprehensive molecular screening by next generation sequencing reveals a distinctive mutational profile of KIT/PDGFRA genes and novel genomic alterations: results from a 20-year cohort of patients with GIST from north-western Greece

Introduction

Gastrointestinal stromal tumours (GIST) are mesenchymal neoplasms that usually carry an activating mutation in KIT or platelet-derived growth factor receptor alpha (PDGFRA) genes with predictive and prognostic significance. We investigated the extended mutational status of GIST in a patient population of north-western Greece in order to look at geopraphic/genotypic distinctive traits.

Patient and methods

Clinicopathological and molecular data of 38 patients diagnosed from 1996 to 2016 with GIST in the region of Epirus in Greece were retrospectively assessed. Formalin-fixed paraffin-embedded tumours were successfully analysed for mutations in 54 genes with oncogenic potential. Next generation sequencing was conducted by using the Ion AmpliSeqCancer Hotspot Panel V.2 for DNA analysis (Thermofisher Scientific).

Results

Among 38 tumours, 24 (63.16%) and seven (18.42%) of the tumours harboured mutations in the KIT and PDGFRA genes, respectively, while seven (18.42%) tumours were negative for either KIT or PDGFRA mutation. No mutations were detected in five (13.16%) cases. Concomitant mutations of BRAF and fibroblast growth factor receptor 3 (FGFR3) genes were observed in two patients with KIT gene mutation. Two patients with KIT/PDGFRA wild-type GIST had mutations in either KRAS or phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) genes. There was no significant survival difference regarding the exonic site of mutation in either KIT or PDGFRA gene. The presence of a mutation in pathway effectors downstream of KIT or PDGFRA, such as BRAF, KRAS or PIK3CA, was associated with poor prognosis. Adverse prognosticators were also high mitotic index and the advanced disease status at diagnosis.

Conclusions

We report comparable incidence of KIT and PDGFRA mutation in patients with GIST from north-western Greece as compared with cohorts from other regions. Interestingly, we identified rare mutations on RAS, BRAF and PIK3CA genes in patients with poor prognosis.

Tyrosine kinase inhibitor sensitive PDGFRΑ mutations in GIST: Two cases and review of the literature

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal malignancies of the gastrointestinal tract. Most GISTs harbor a c-KIT (80%) or a PDGFRα (10%) mutation that leads to constitutive activation of the tyrosine kinase receptor. Response to treatment with tyrosine kinase inhibitors (TKIs) is dependent on mutational status of the tumor. The most common mutation in PDGFRα, D842V, is known to be imatinib resistant. Almost all other PDGFRα mutations are imatinib sensitive. We describe two patients with a PDGFRα exon 18 mutated GIST responding to treatment with TKIs. One of these patients has a p.M844_S847 deletion, not previously described in relation with TKI treatment response. Mutations in circulating tumor DNA were detectable with digital droplet PCR in serial plasma samples taken during treatment and correlated with treatment response of both patients. Computer 3D-modeling of the PDGFRα kinase domain of these two variants revealed no direct interference in imatinib or sunitinib binding and no effect in its activity in contrast to the reported structure of the imatinib resistant D842V mutation.

An overview is given of the literature regarding the evidence of patients with different PDGFRα mutated GISTs on response to TKIs. The findings emphasize the use of mutational analysis in GIST to provide patients personalized treatment. Detection of mutations in plasma is feasible and can provide real-time information concerning treatment response. We suggest to register GIST patients with these uncommon mutations in a prospective international database to understand the tumor biology and obtain more evidence of such mutations to predict treatment response.

Comparison of Different Risk Classification Systems in 558 Patients with Gastrointestinal Stromal Tumors after R0-Resection

Background: Due to adjuvant treatment concepts for patients with R0-resected gastrointestinal stromal tumors (GIST), a reproducible and reliable risk classification system proved of utmost importance for optimal treatment of patients and prediction of prognosis. The aim of this study was to reevaluate the impact of five widely-applied and well-established GIST risk classification systems (i.e., scores by Fletcher, Miettinen, Huang, Joensuu, and TNM classification) on a series of 558 GIST patients with long-term follow-up after R0 resection. Methods: Tumor size, mitotic count and site were used in variable combination to predict high- and low risk patients by the use of the five risk classification models. For survival analyses disease-specific survival, disease-free survival and overall-survival were investigated. Patients with initial metastatic disease or incompletely resectable tumors were excluded. Results: All GIST classification models distinguished well between patients with high-risk and low-risk tumors and none of the five risk systems was superior to predict patient outcome. The models showed significant heterogeneity. There was no significant difference between the different risk-groups regarding overall-survival. Subdivision of GIST patients with very low- and low-risk appeared to be negligible. Conclusions: Currently applied GIST risk classification systems are comparable to predict high- or low-risk patients with initial non-metastatic and completely resected GIST. However, the heterogeneity of the high-risk group and the absence of differences in overall survival indicate the need for more precise tumor- and patient-related criteria for better stratification of GIST and identification of patients who would benefit best from adjuvant tyrosine kinase inhibitor therapy.

Correlation between mutational status and survival and second cancer risk assessment in patients with gastrointestinal stromal tumors: a population-based study

BACKGROUND

Gastrointestinal stromal tumors are sarcomas of the digestive tract characterized by mutations mainly located in the c-KIT or in the platelet-derived growth factor receptor (PDGFR)-alpha genes. Mutations in the BRAF gene have also been described. Our purpose is to define the distribution of c-KIT, PDGFR and BRAF mutations in a population-based cohort of gastrointestinal stromal tumors (GIST) patients and correlate them with anatomical site, risk classification and survival. In addition, as most of the GIST patients have a long survival, second cancers are frequently diagnosed in them. We performed a second primary cancer risk assessment.

METHODS

Our analysis was based on data from Tarragona and Girona Cancer Registries. We identified all GIST diagnosed from 1996 to 2006 and performed a mutational analysis of those in which paraffin-embedded tissue was obtained. Observed (OS) and relative survival (RS) were calculated according to risk classifications and mutational status. Multivariate analysis of variables for observed survival and was also done.

RESULTS

A total of 132 GIST cases were found and we analyzed mutations in 108 cases. We obtained 53.7% of mutations in exon 11 and 7.4% in exon 9 of c-KIT gene; 12% in exon 18 and 1.9% in exon 12 of PDGFR gene and 25% of cases were wild type GIST. Patients with mutations in exon 11 of the c-KIT gene had a 5-year OS and RS of 59.6% and 66.3%, respectively. Patients with mutations in exon 18 of the PDGFR gene had a 5-year OS and RS of 84.6% and 89.7%. In multivariate analysis, only age and risk group achieved statistical significance for observed survival. GIST patients had an increased risk of second cancer with a hazard ratio of 2.47.

CONCLUSIONS

This population-based study shows a spectrum of mutations in the c-KIT and PDGFR genes in GIST patients similar to that previously published. The OS and RS of GIST with the exon 18 PDGFR gene mutation could indicate that this subgroup of patients may be less aggressive and have a good prognosis, although less sensitive to treatment at recurrence. In our study, GIST patients have an increased risk of developing a second neoplasm.

Additional Primary Malignancies in Patients with Gastrointestinal Stromal Tumor (GIST): A Clinicopathologic Study of 260 Patients with Molecular Analysis and Review of the Literature

BACKGROUND

The incidence of other primary neoplasms in gastrointestinal stromal tumor (GIST) patients is relatively high. Our aim was to better characterize the clinicopathologic and molecular relationships in a cohort of GIST patients.

METHODS

All GIST patients with tumor samples sent for molecular testing were identified via electronic medical records. Clinicopathologic characteristics of GIST and additional primary malignancies were analyzed.

RESULTS

Of 260 patients, 50 (19 %) had at least one additional primary malignancy. In 33 patients, separate primary neoplasms predated their GIST diagnosis and most commonly included: prostate (n = 9), breast (n = 8), and hematologic (n = 5). Renal (n = 4) and hematologic (n = 3) malignancies were the most frequent cancers identified after GIST diagnosis. The majority (8 of 12, 66 %) of malignancies diagnosed after GIST were found incidentally. Patients who developed other malignancies after GIST more often had KIT exon 11 mutations (100 vs. 66 %, P = 0.01). In comparison to patients with only GIST, patients with a second primary neoplasm of any chronology had GISTs with increased mitotic rate (≥5 per 50 high-power fields) (P = 0.0006). Literature review revealed colorectal cancer, gastric, prostate, renal, leukemia, and desmoid-type fibromatosis as the most common secondary neoplasms.

CONCLUSIONS

Nineteen percent of GIST patients develop other malignancies. This is the first report to describe a relationship between additional primary malignancy and both mutation and mitotic rate of GIST. Although the basis of these relationships remains to be investigated, caution in the clinical management of GIST patients with additional lesions is warranted.

Gastrointestinal stromal tumors: a case-only analysis of single nucleotide polymorphisms and somatic mutations

Background

Gastrointestinal stromal tumors are rare soft tissue sarcomas that typically develop from mesenchymal cells with acquired gain-in-function mutations in KIT or PDGFRA oncogenes. These somatic mutations have been well-characterized, but little is known about inherited genetic risk factors. Given evidence that certain susceptibility loci and carcinogens are associated with characteristic mutations in other cancers, we hypothesized that these signature KIT or PDGFRA mutations may be similarly fundamental to understanding gastrointestinal stromal tumor etiology. Therefore, we examined associations between 522 single nucleotide polymorphisms and seven KIT or PDGFRA tumor mutations types. Candidate pathways included dioxin response, toxin metabolism, matrix metalloproteinase production, and immune and inflammatory response.

Methods

We estimated odds ratios and 95% confidence intervals for associations between each candidate SNP and tumor mutation type in 279 individuals from a clinical trial of adjuvant imatinib mesylate. We used sequence kernel association tests to look for pathway-level associations.

Results

One variant, rs1716 on ITGAE, was significantly associated with KIT exon 11 non-codon 557–8 deletions (odds ratio = 2.86, 95% confidence interval: 1.71-4.78) after adjustment for multiple comparisons. Other noteworthy associations included rs3024498 (IL10) and rs1050783 (F13A1) with PDGFRA mutations, rs2071888 (TAPBP) with wild type tumors and several matrix metalloproteinase SNPs with KIT exon 11 codon 557–558 deletions. Several pathways were strongly associated with somatic mutations in PDGFRA, including defense response (p = 0.005) and negative regulation of immune response (p = 0.01).

Conclusions

This exploratory analysis offers novel insights into gastrointestinal stromal tumor etiology and provides a starting point for future studies of genetic and environmental risk factors for the disease.

Gastrointestinal stromal tumors, somatic mutations and candidate genetic risk variants

Gastrointestinal stromal tumors (GISTs) are rare but treatable soft tissue sarcomas. Nearly all GISTs have somatic mutations in either the KIT or PDGFRA gene, but there are no known inherited genetic risk factors. We assessed the relationship between KIT/PDGFRA mutations and select deletions or single nucleotide polymorphisms (SNPs) in 279 participants from a clinical trial of adjuvant imatinib mesylate. Given previous evidence that certain susceptibility loci and carcinogens are associated with characteristic mutations, or "signatures" in other cancers, we hypothesized that the characteristic somatic mutations in the KIT and PDGFRA genes in GIST tumors may similarly be mutational signatures that are causally linked to specific mutagens or susceptibility loci. As previous epidemiologic studies suggest environmental risk factors such as dioxin and radiation exposure may be linked to sarcomas, we chose 208 variants in 39 candidate genes related to DNA repair and dioxin metabolism or response. We calculated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the association between each variant and 7 categories of tumor mutation using logistic regression. We also evaluated gene-level effects using the sequence kernel association test (SKAT). Although none of the association p-values were statistically significant after adjustment for multiple comparisons, SNPs in CYP1B1 were strongly associated with KIT exon 11 codon 557-8 deletions (OR = 1.9, 95% CI: 1.3-2.9 for rs2855658 and OR = 1.8, 95% CI: 1.2-2.7 for rs1056836) and wild type GISTs (OR = 2.7, 95% CI: 1.5-4.8 for rs1800440 and OR = 0.5, 95% CI: 0.3-0.9 for rs1056836). CYP1B1 was also associated with these mutations categories in the SKAT analysis (p = 0.002 and p = 0.003, respectively). Other potential risk variants included GSTM1, RAD23B and ERCC2. This preliminary analysis of inherited genetic risk factors for GIST offers some clues about the disease's genetic origins and provides a starting point for future candidate gene or gene-environment research.

Adjuvant treatment of GIST: patient selection and treatment strategies

Tyrosine kinase inhibitors that target the key molecular drivers of gastrointestinal stromal tumour (GIST) are effective treatments of advanced-stage GIST. Yet, most of these patients succumb to the disease. Approximately 60% of patients with GIST are cured by surgery, and these individuals can be identified by risk stratification schemes based on tumour size, mitosis count and site, and assessment of rupture. Two large randomized trials have evaluated imatinib as adjuvant treatment for operable, KIT-positive GIST; adjuvant imatinib substantially improved time to recurrence. One of these trials reported that 3 years of adjuvant imatinib improves overall survival of patients who have a high estimated risk for recurrence of GIST compared with 1 year of imatinib. The optimal adjuvant strategy remains unknown and some patients might benefit from longer than 3 years of imatinib treatment. However, a strategy that involves GIST risk assessment following surgery using a validated scheme, administration of adjuvant imatinib for 3 years, patient monitoring during and after completion of imatinib to detect recurrence early, and reinstitution of imatinib if GIST recurs is a reasonable choice for care of patients with high-risk GIST.