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

Prognostic factors for primary gastrointestinal stromal tumours: are they the same in the multidisciplinary treatment era?

PURPOSE

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumour of the gastrointestinal tract. The introduction of tyrosine kinase inhibitors (TKIs) has lead to increasing use of combination of medical and surgical therapy. The aim of this study was to look at outcomes from a series of surgically treated GISTs and determine prognostic factors in the context of multimodal therapy.

METHODS

We analysed 104 single surgeon's patients with GIST. End points of the study were disease-specific survival (DSS), disease-free survival (DFS) and post-operative complications.

RESULTS

Three- and 5-year DSS rates were 96.7 and 94.6 %. On univariate analysis, clear resection margins were predictive of DSS. Patients with R2 resection had a worse prognosis (3-year DSS rate of 83.3 %; 5-year DSS rate of 62.5 %) compared to patients with R0 (3-year DSS rate of 98 %; 5-year DSS rate of 98 %) or R1 resection (3-year DSS rate of 100 %; 5-year DSS rate of 100 %) (R0 vs R1 vs. R2 p = 0.001). Pre-operative factors associated with R2 resection were clinical metastatic disease (p < 0.001), non-gastric tumour site (p = 0.002) and large tumour diameter (p = 0.031). Three- and 5-year DFS rates were 65.5 and 59.8 %. Serosal perforation (p = 0.013) and mitotic rate (p = 0.05) were found to be independently predictive of increased DFS. The presence of serosal perforation was associated with tumour site (p = 0.018), mitotic rate (p = 0.035), tumour diameter (p < 0.001), growth pattern (p = 0.007) and age (p = 0.040).

CONCLUSIONS

In the multidisciplinary management of GIST, serosal perforation may represent an additional predictor of recurrence along with mitotic rate. Complete macroscopic surgical resection is the most reliable prognostic factor, and an aggressive surgical approach should be advocated.

Laparoscopic sphincter-preserving surgery (intersphincteric resection) after neoadjuvant imatinib treatment for gastrointestinal stromal tumor (GIST) of the rectum

BACKGROUND

Gastrointestinal stromal tumors (GISTs) of the rectum are rarely found, and radical surgery such as abdominoperineal resection would be necessary for large rectal GIST. On the other hand, therapy for GIST has changed significantly with the use of imatinib. Neoadjuvant imatinib therapy may reduce tumor size and may potentially prevent extended surgery. Moreover, when sphincter-preserving surgery is carried out laparoscopically, it can be performed as minimally invasive surgery with preservation of the anus.

METHODS

From 2008 to 2011, five patients with rectal GIST were treated in our hospital. All patients received preoperative imatinib treatment (400 mg/day) and underwent laparoscopic sphincter-preserving surgery after 4-12 months of this treatment.

RESULTS

Initial median tumor size was 31 mm (range, 24-88). At the time of operation, the median tumor size was 24 mm (range, 11-52). Sphincter-preserving surgery was performed in all patients. Three patients underwent laparoscopic intersphincteric resection (ISR), and two patients underwent transanal full-thickness local resection and recto-anal anastomosis following laparoscopic ISR. Macroscopically complete resection was achieved, and microscopically, the resection margin was not involved of residual tumors. The median duration of postoperative hospital stay was 16 days (range, 13-30). No recurrence occurred in all patients during 1 to 4 years.

CONCLUSIONS

The present study suggests that neoadjuvant imatinib therapy might be effective to prevent extended surgery for rectal GIST, and laparoscopic sphincter-preserving surgery is safe and technically feasible. We recommend a combination of neoadjuvant imatinib therapy and laparoscopic ISR for locally advanced rectal GIST.

Clinicopathologic factors predicting outcomes in patients with gastrointestinal stromal tumors of the rectum and colon

Limited information is available concerning the clinicopathologic profile of colorectal gastrointestinal stromal tumors (GISTs), which are relatively rare, as well as survival rates following surgical resection. The present study was designed to describe the clinicopathologic characteristics of patients with colorectal GISTs and identify potential factors that may predict postoperative survival outcomes. We reviewed the medical records of 67 patients with colorectal GISTs who underwent surgical resection between January 2000 and December 2012. Clinicopathologic factors affecting overall survival were assessed using the Kaplan-Meier method and multivariate Cox proportional hazards models. The median age at diagnosis was 57 years (range, 32-79 years), with a male-to-female ratio of 1.68. Tumor size varied from 0.2 to 11 cm, with a median size of 5.7 cm. Sixty-two tumors (93%) were positive for CD117, 53 (79%) for CD34, 6 (9%) for PDGFRA, 15 (22%) for SMA, 5 (8%) for S100, and 39 (58%) for vimentin. The overall median survival time was 54 months (95% confidence interval, 32-59 months), and the 1-, 3-, and 5-year overall survival rates were 89.6, 63.9, and 34.4%, respectively. High-risk tumors (determined by histologic grade, size, and other histologic variables) were associated with poor prognosis (hazard ratio, 1.83; 95% confidence interval, 1.21-2.78), and patients who received adjuvant treatment with imatinib had significantly longer median overall survival times than patients who did not (hazard ratio, 0.43; 95% confidence interval, 0.24-0.80). In patients with colorectal GISTs, high-risk tumor histologic grade can predict poor prognosis, and patients may benefit from adjuvant treatment with imatinib. Findings from the present study may provide information to establish evidence-based management strategies for colorectal GISTs.

Prognostic value of mutational characteristics in gastrointestinal stromal tumors: a single-center experience in 275 cases

The objective of this study was to investigate the impact of KIT/PDGFRA mutations on the prognosis of gastrointestinal stromal tumors (GISTs). In the present study, genotype analyses were performed based on GIST samples from 275 patients. The relationship between mutation and clinicopathological characteristics were explored. All factors were evaluated for their impacts on relapse-free survival (RFS). Briefly, the results of genotype analyses showed that mutations were identified in 258 (93.8 %) patients, and deletion was the most frequent type of mutation accounting for 47.3 % (122/258) of all mutation cases, followed by substitution (87/258, 33.7 %) and duplication (49/258, 19.0 %). Moreover, for KIT exon 11 mutation, the most frequently involved area was from codon 557 to 560. Deep analyses showed that the mutation types were correlated with tumor location (P = 0.005), tumor size (P = 0.022), mitosis rate (P < 0.001), risk grade (P < 0.001), and relapse (P = 0.004). Furthermore, delW557-K558 correlated with mitosis rate (P = 0.042) and relapse (P = 0.036), and delTyr568/570 correlated with tumor origin (P = 0.018). Most importantly, mitotic rate [HR = 2.901 (95 % CI 1.094-7.695), P = 0.032] and risk grade [HR = 9.629 (95 % CI 1.997-46.416), P = 0.005] would be the representative traditional prognostic factors, and deletion with >3 codons would be an novel independent predictor of poor outcome for RFS in GIST patients with deletion mutation of KIT exon 11 [HR = 7.970 (95 % CI 1.774-35.803), P = 0.007]. All results indicated that mutation determined clinicopathological features and prognosis of GISTs, and more than three codons involvement may be a novel adverse indicator.

Ten-year review of gastrointestinal stromal tumours at a tertiary referral hospital in New Zealand

BACKGROUND

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the gastrointestinal tract and make up 1-2% of all gastrointestinal malignancies. Traditionally, the treatment of choice for primary disease is surgical resection; however, no single surgeon or institution gets extensive exposure to these patients so appropriate decision-making is difficult, particularly since the introduction of the tyrosine kinase inhibitor imatinib, which has become an important additional management tool.

METHOD

All patients were diagnosed and treated for GISTs in Christchurch Hospital (Christchurch, New Zealand) between 1 January 2000 and 31 December 2010. We maintain a prospective database of all patients with GISTs. Data on clinical and histopathological variables, management and survival outcomes were recorded. These were then reviewed.

RESULTS

There were 93 patients in this study. Fifty were women. Median age was 69 (interquartile range (IQR) 59-76) years. Fifty-one tumours were located in the stomach, 27 in the small bowel, six in the colon, three in the oesophagus, one in the rectum and five were extra-gastrointestinal. In total, 22 patients received imatinib therapy; four patients with metastatic disease had imatinib as sole therapy. The median follow-up was 58 (IQR 30-90) months. The 5-year overall survival and disease-free survival (DFS) for the entire study population was 69% and 64%, respectively. The 5-year DFS was higher for all patients who have localized disease when compared with those who have metastatic disease (76% versus 28%, P-value 0.001).

CONCLUSION

Surgery aiming at an R0 resection remains the mainstay of treatment. We propose the most effective way to grow the knowledge base in New Zealand is the establishment of a national register, thereby allowing better clinical decision-making by interpretation of a larger data set.

Laparoscopic resection of gastric and small bowel gastrointestinal stromal tumors: 10-year experience at a single center

BACKGROUND

Complete curative resection remains the treatment of choice for nonmetastatic gastrointestinal stromal tumors (GISTs). The safety and feasibility of laparoscopy in the treatment of this disease has been shown, however, the long-term oncologic outcomes of this technique remain unclear.

STUDY DESIGN

An ongoing prospectively maintained database including all laparoscopically resected gastric and small bowel GISTs (n = 116) at Mount Sinai Medical Center from July 1999 to December 2011 was retrospectively analyzed. Recurrence and survival outcomes were calculated using the Kaplan-Meier method and compared with log-rank test.

RESULTS

Tumors were of gastric (77.6%) and small bowel (22.4%) origins. Overall mean tumor size was 4.0 cm (±2.7 cm) and R0 resection was achieved in 113 (97.4%) cases. Overall perioperative complication rate was 14.7%, with a reoperative rate of 4.3% at 90 days. When comparing gastric with small bowel GISTs, a more acute presentation requiring emergent resections was noted in patients with small bowel GISTs (p = 008). However tumor size, operative data, and perioperative outcomes were comparable in both groups (p = NS). At a median follow-up of 56.4 months (range 0.1 to 162.4 months), recurrence rate was 7.8% and comparable in both gastric and small bowel GISTs (p = NS). Risk factors for recurrence on univariate analysis were presence of ulceration/necrosis (p < 0.001) and tumor size >5 cm (p = 0.05). Overall 10-year survival rate was 90.8%. Gastric and small bowel overall survival rates were similar (90.7% vs 91.3%, respectively). Overall 10-year disease-free survival was 80.0% (84.3% gastric vs 71.6% small bowel; p = NS).

CONCLUSIONS

Our series demonstrates the safety and feasibility of laparoscopy in patients undergoing resection of small bowel and gastric GISTs. Comparable long-term oncologic outcomes with a 10-year survival of 90.8% were achieved.

Development of enterohepatic fistula after embolization in ileal gastrointestinal stromal tumor: A case report

Gastrointestinal stromal tumor (GIST) is a rare mesenchymal tumor of the gastrointestinal tract that has been associated with the formation of fistulas to adjacent organs in few case reports. However, GIST with enterohepatic fistula has not been reported. Here we report the case of an enterohepatic fistula that occurred after embolization of a liver mass originating in the distal ileum. An 87-year-old woman was hospitalized for melena. On initial conventional endoscopy, a bleeding focus in the gastrointestinal tract was not found. Because of massive hematochezia, enteroscopy was performed through the anus. A protruding, ulcerative mass was found in the distal ileum that was suspected to be the source of the bleeding; a biopsy sample was taken. Electrocoagulation was not successful in controlling the bleeding; therefore, embolization was performed. After embolization, the patient developed a high fever and severe abdominal tenderness with rebound tenderness. Follow-up abdominopelvic computed tomography revealed an enterohepatic fistula between the liver and distal ileum. The fistula was treated surgically by segmental resection of the distal ileum and unlooping of the liver mass.

Long-term results of adjuvant imatinib mesylate in localized, high-risk, primary gastrointestinal stromal tumor: ACOSOG Z9000 (Alliance) intergroup phase 2 trial

OBJECTIVE

To conduct the first adjuvant trial of imatinib mesylate for treatment of gastrointestinal stromal tumor (GIST).

BACKGROUND

GIST is the most common sarcoma. Although surgical resection has been the mainstay of therapy for localized, primary GIST, postoperative tumor recurrence is common. The KIT protooncogene or, less frequently, platelet-derived growth factor receptor alpha is mutated in GIST; the gene products of both are inhibited by imatinib mesylate.

METHODS

This was a phase II, intergroup trial led by the American College of Surgeons Oncology Group, registered at ClinicalTrials.gov as NCT00025246. From September 2001 to September 2003, we accrued 106 patients who had undergone complete gross tumor removal but were deemed at high risk for recurrence. Patients were prescribed imatinib 400 mg per day for 1 year and followed with serial radiologic evaluation. The primary endpoint was overall survival (OS).

RESULTS

After a median follow-up of 7.7 years, the 1-, 3-, and 5-year OS rates were 99%, 97%, and 83%, which compared favorably with a historical 5-year OS rate of 35%. The 1-, 3-, and 5-year recurrence-free survival (RFS) rates were 96%, 60%, and 40%. On univariable analysis, age and mitotic rate were associated with OS. On multivariable analysis, the RFS rate was lower with increasing tumor size, small bowel site, KIT exon 9 mutation, high mitotic rate, and older age.

CONCLUSIONS

Adjuvant imatinib in patients with primary GIST who are at high risk of recurrence prolongs OS compared with that of historical controls. Optimal duration of adjuvant therapy remains undefined. (NCT00025246).

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.

Surgical resection should be taken into consideration for the treatment of small gastric gastrointestinal stromal tumors

BACKGROUND

The National Comprehensive Cancer Network (NCCN) recommends conservative follow-up for gastric gastrointestinal stromal tumors (GISTs) less than 2 cm. The aim of the present study was to investigate the clinical and pathological features of small gastric GISTs, re-evaluate the risk potential, and discuss the treatment strategy of small gastric GISTs.

METHODS

In this retrospective study, 63 cases of small gastric GISTs (less than 2 cm) were resected surgically from May 2010 to March 2013 in our department. Clinicopathological factors were collected and the malignant potential of small gastric GISTs was analyzed.

RESULTS

The mitotic index of 14 out of 63 cases (22.22%) exceeded 5. The malignant potential of small gastric GISTs was related to tumor location (P = 0.0218). The mitotic index of 4 out of 8 GISTs (50%) located in gastric cardia exceeded 5, 8 out 28 GISTs (28.57%) located in the gastric fundus exceeded 5, and only 2 out of 27 GISTs (7.41%) located in the gastric body exceeded 5. We also discovered a good consistency between mitotic index and Ki-67 expression of small gastric GISTs.

CONCLUSIONS

Gastric GISTs less than 2 cm also have malignant potential. Thus, we recommended surgical resection of all small gastric GISTs once diagnosed.

Gastrointestinal stromal tumour

Gastrointestinal stromal tumours (GISTs) are mesenchymal neoplasms that arise in the gastrointestinal tract, usually in the stomach or the small intestine and rarely elsewhere in the abdomen. They can occur at any age, the median age being 60-65 years, and typically cause bleeding, anaemia, and pain. GISTs have variable malignant potential, ranging from small lesions with a benign behaviour to fatal sarcomas. Most tumours stain positively for the mast/stem cell growth factor receptor KIT and anoctamin 1 and harbour a kinase-activating mutation in either KIT or PDGFRA. Tumours without such mutations could have alterations in genes of the succinate dehydrogenase complex or in BRAF, or rarely RAS family genes. About 60% of patients are cured by surgery. Adjuvant treatment with imatinib is recommended for patients with a substantial risk of recurrence, if the tumour has an imatinib-sensitive mutation. Tyrosine kinase inhibitors substantially improve survival in advanced disease, but secondary drug resistance is common.

Gastrointestinal stromal tumors: risk assessment and adjuvant therapy

Adjuvant imatinib prolongs recurrence-free survival and probably overall survival of patients who have undergone surgery for gastrointestinal stromal tumor (GIST). Estimation of the risk of recurrence with a prognostication tool and tumor mutation analysis is essential before imatinib initiation, because approximately 60% of patients with GIST with operable tumor are cured by surgery alone and some mutated tyrosine kinases are insensitive to imatinib. Adjuvant imatinib is usually administered for 3 years at the dose of 400 mg once daily. Early detection of tumors that recur despite adjuvant therapy with longitudinal imaging of the abdomen is likely beneficial.

Targeted therapy for cancer: the gastrointestinal stromal tumor model

Gastrointestinal stromal tumors (GISTs) are unique tumors, arising largely due to oncogenic mutations in KIT or PDGFRA tyrosine kinases. Although surgery remains the most effective treatment, the remarkable clinical success achieved with kinase inhibition has made GIST one of the most successful examples of targeted therapy for the treatment of cancer. The insight gained from this approach has allowed a deeper understanding of the molecular biology driving kinase dependent cancers, and the adaptations to kinase inhibition, linking genotype to phenotype. Mutation tailored kinase inhibition with second generation TKI's, and combination immunotherapy to harness the effects of TKIs remain exciting areas of investigation.

Patterns of recurrence of gastrointestinal stromal tumour (GIST) following complete resection: implications for follow-up

AIM

To determine the frequency, time course and sites of recurrence following surgical resection of gastrointestinal stromal tumours (GIST) and to evaluate the performance of a risk-based surveillance protocol in detection of recurrence.

METHODS

Eighty-one patients on surveillance following complete resection of GIST were included. Patients were stratified into risk groups according to accepted histopathological criteria. Computed tomography (CT) examinations were retrospectively reviewed to determine rates, sites and imaging characteristics of recurrence and to assess compliance with the local follow-up protocol.

RESULTS

The median time of follow-up was 41 months. Nineteen patients suffered recurrence, all of whom were in the high-risk group. Fifty-eight percent of relapses occurred within 1 year and 84% within 3 years. Even within the high-risk group, patients with relapse had significantly larger (mean 15 versus 10.4 cm, p < 0.05) and more mitotically active primary tumours (mean 33.7 versus 5.6 mitoses per 50 high-power fields; p < 0.05) than those with no relapse. Relapse was to the liver in 12 cases (63%) and to the omentum and mesentery in nine cases (47%), and was asymptomatic in three-quarters of patients.

CONCLUSIONS

The high incidence of GIST recurrence in the high-risk group in the first 3 years after surgery supports the use of intensive imaging surveillance in this period. Relapse is often asymptomatic and commonly occurs to the liver, omentum and mesentery. Stratification by tumour factors may enable improved tailoring of surveillance protocols within the high-risk group in the future.

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.

The SSG XVIII/AIO trial: results change the current adjuvant treatment recommendations for gastrointestinal stromal tumors

Although adjuvant imatinib (IM) for high risk GIST is an accepted treatment consideration, the duration of therapy remains controversial. The recently published SSGXVIII/AIO randomized clinical trial of 3 years vs. 1 year of adjuvant IM has established a benefit of RFS and OS for the 3 year cohort. Future studies are necessary to continue to further delineate risk variables for GIST recurrence.

Predictors of unsuccessful laparoscopic resection of gastric submucosal neoplasms

BACKGROUND

While laparoscopy has become integral to the performance of foregut surgery, its optimal use in resection of gastric submucosal neoplasms, including gastrointestinal stromal tumors (GISTs), remains uncertain. Concern exists for technical feasibility related to tumor size and location, as well as oncologic outcome.

METHODS

From 2002 to 2012, 106 patients underwent resection for gastric submucosal neoplasms, comprising 79 laparoscopic and 27 open resections. Median follow-up was 15 months.

RESULTS

Patients were 62 ± 14 years and 56 % male. Mean tumor size was 5.5 ± 4.3 cm, with 76 % being GISTs. A total of 8 (10 %) conversions occurred in the laparoscopic cohort. On multivariate analysis, conversion was predicted by size greater than 8 cm, while recurrence was predicted by mitotic index (p < 0.05). Laparoscopic resection resulted in better perioperative outcomes, with less morbidity, operative time, blood loss, and length of stay (p < 0.05). No significant difference was seen in survival, with 90 % and 81 % alive 3 years after laparoscopic and open resection, respectively (HR 0.4; 95 % CI 0.1-1.3; p = 0.13).

CONCLUSIONS

Laparoscopic resection is feasible and effective in the management of gastric submucosal neoplasms, including GISTs. Caution should be reserved for tumors greater than 8 cm. Oncologic outcome appears to be predicted by tumor biology as opposed to surgical approach.

Primary gastrointestinal stromal tumors: Current advances in diagnostic biomarkers, prognostic factors and management of its duodenal location

Gastrointestinal stromal tumors (GIST) constitute 1-3% of all gastrointestinal malignancies and is the most common mesenchymal tumor of the gastrointestinal tract. Although GIST were first described in the literature in the year 1941, important advances of kit mutation and tyrosine kinase inhibitors were not made to understand and manage GIST until the last decade. Here current advances in research of possible cellular origin, diagnostic biomarkers and prognostic factors of primary GIST are reviewed, and the management of primary duodenal GIST is focused on due to its specific location. It is possible that personalized assessment and therapy will turn out to be another milestone for primary GIST.

Role of Ki-67 as a prognostic factor in gastrointestinal stromal tumors

AIM: To investigate primarily the prognostic value of Ki-67, as well as other parameters, in gastrointestinal stromal tumors (GISTs).

METHODS: Ki-67, c-KIT, platelet-derived growth factor receptor-alpha (PDGFRα), smooth muscle actin (SMA), CD34, S100 were stained for immunohistochemistry which was performed on formalin-fixed, paraffin-embeded sections on representative block from each case. Proliferation index counted by Ki-67 antibody was calculated as a number of positive nuclear reaction over 100 cells. Immunoreactivity for c-KIT and PDGFRα was evaluated semiquantitatively (weak, intermediate, strong) and for c-KIT type of reactivity was analyzed (cytoplasmic, membrane and "dot-like" staining). Immunoreactivity for SMA, CD34 and S100 were was evaluated as positive or negative antigen expression. Pathologic parameters investigated in this study included tumor size, cell type (pure spindle, pured epitheloid mixed spindle and epitheloid), mitotic count, hemorrhage, necrosis, mucosal ulceration. Clinical data included age, gender, primary tumor location and spread of disease. χ² test and Student's t-test were used for comparisons of baseline characteristics. The Cox’s proportional hazard model was used for univariable and multivariable analyses. Survival rates were calculated by Kaplan-Meier method and statistical significance was determined by the log-rank test.

RESULTS: According to the stage of disease, there were 36 patients with localized disease, 29 patients with initially localized disease but with its recurrence in the period of follow up, and finally, 35 patients had metastatic disease from the very beginning of disease. Tumor originated most commonly in the stomach (41%), small intestine was the second most common location (36%). The mean size of primary tumors was 6.5 cm. The mean duration of follow-up was 60 mo. Multiple parameters were analyzed for their effect on overall survival, but no one reached statistical significance (P = 0.06). Analysis of time to progression/relapse in initially localized disease (univariate analysis), tumor size, mitotic count, Ki-67 and type of d-KIT distribution (cytoplasmic vs membrane/”dot-like”) showed statistically significant correlation. In multivariate analysis in the group of patients with localized disease, there were only 2 parameters that have impact on relapse, Ki-67 and SMA (P < 0.0001 and P < 0.034, respectively). Furthermore, Ki-67 was analyzed in localized disease vs localized with recurrence and metastatic disease. It was shown that there is a strict difference between these 2 groups of patients (median value was 2.5 for localized disease vs 10.0 for recurrent/metastatic disease, P < 0.0001). It was also shown that the cut-off value which is still statistically significant in terms of relapse on the level of 6%. The curves for survival on that cut-off level are significantly different (P < 0.04, Cox F).

CONCLUSION: Ki-67 presents a significant prognostic factor for GIST recurrence which could be of great importance in evaluating malignant potential of disease.

Gastrointestinal stromal tumors in Turkey: experiences from 3 centers

BACKGROUND

Gastrointestinal stromal tumors (GIST) are rare tumors of the gastrointestinal system. The most common primary site of GIST is the stomach. The treatment is primarily surgery, and the standard medical therapy is imatinib. Long-term survival can be obtained with good follow-up and treatment.

MATERIALS AND METHODS

In this study, data entry was performed using a web-based patient registry system for patients who were referred to 3 centers and retrospectively were diagnosed with GIST.

RESULTS

The study cohort consisted of 249 patients, including 160 men (64.3%) and 89 women (35.7%). The mean age was 59 years (range 21-90 years). Initially, 69.9% of the patients had local disease, while 30.1% had metastatic disease. The tumor was located in the stomach in 45.6% of patients. According to the Fletcher risk classification, the very low risk group included 8 subjects (3.2%), the low risk group included 40 subjects (16.1%), the moderate risk group included 56 subjects (22.5%), and the high risk group included 117 subjects (47%); the unspecified group included 28 subjects (11.5%).

CONCLUSION

These data are important for revealing the clinicopathologic characteristics and survival data of patients with GIST, who are treated and followed up in Turkey.

Treatment Results of Small Intestinal Gastrointestinal Stromal Tumors Less than 10 cm in Diameter: A Comparison between Laparoscopy and Open Surgery

Purpose

To evaluate the technical feasibility and oncologic safety, we assessed the short-term and long-term outcomes of laparoscopic resection of the small bowel gastrointestinal stromal tumors smaller than 5 cm by comparing those of open surgery by subgroup analysis based on tumor size.

Materials and Methods

From November 1993 to January 2011, 41 laparoscopic resections were performed among the 95 patients who underwent resection of small intestine ≤10 cm in diameter. The clinicopathologic features, perioperative outcomes, recurrences and survival of these patients were reviewed.

Results

The postoperative morbidity rates were comparable between the 2 groups. Laparoscopic surgery group showed significantly shorter operative time (P=0.004) and duration of postoperative hospital stay (P<0.001) than open surgery group and it was more apparent in the smaller tumor size group. There were no difference in 5-year survival for the laparoscopic surgery versus open surgery groups (P=0.163), and in 5-year recurrence-free survival (P=0.262). The subgroup analysis by 5 cm in tumor size also shows no remarkable differences in 5-year survival and recurrence-free survival.

Conclusions

Laparoscopic resection for small bowel gastrointestinal stromal tumors of size less than 10 cm has favorable short-term postoperative outcomes, while achieving comparable oncologic results compared with open surgery. Thus, laparoscopic approach can be recommended as a treatment modality for patients with small bowel gastrointestinal stromal tumors less than 10 cm in diameter.

Adjuvant therapy of gastrointestinal stromal tumors (GIST)

Imatinib was proven to be effective for the adjuvant treatment of localized, surgically excised, gastrointestinal stromal tumors (GIST). Currently, there is proof that it is able to delay relapse and prolong survival. An effect on cure rate of localized GIST is still to be proven, given the shape of relapse-free survival curves, which apparently tend to overlap after 2-3 years from completion of the adjuvant period. Although observation for a longer follow-up is needed, attempts to prolong adjuvant therapy beyond the currently standard 3 years have been made and the results are awaited. However, the impact of more prolonged adjuvant intervals on secondary resistance is unknown, so that standard practice is still 3 years in most institutions. The adjuvant choice should be based on a rather precise identification of the relapse risk of the single patient, reserving treatment to the high-risk subgroups. The choice also should be personalized on the basis of genotype: generally, PDGFRA D842V mutated and wild-type GIST are excluded. Additional results from completed trials on a longer follow-up are awaited to further refine such "precision" decision-making. There are several instances in which part of the "adjuvant" treatment may be administered preoperatively, even on the face of a surgically resectable GIST, to make surgery more limited and/or safer.

Prolonged Therapy with Imatinib Mesylate before Surgery for Advanced Gastrointestinal Stromal Tumor Results of a Phase II Trial

Purpose. Proven efficacy of imatinib mesylate in gastrointestinal stromal tumour (GIST) has led to its use in advanced disease and, more recently, in adjuvant and neoadjuvant settings. The purpose of this study was to evaluate the optimal neoadjuvant imatinib duration to reduce the morbidity of surgery and increase the possibility of resection completeness in advanced tumours. Patients and Method. Patients with advanced GIST were enrolled into a registered open-label multicenter trial and received imatinib daily for a maximum of 12 months, followed by en bloc resection. Data were prospectively collected regarding tumour assessment, response rate, surgical characteristics, recurrence, and survival. Results. Fourteen patients with advanced GIST were enrolled. According to RECIST criteria, 6 patients had partial response and 8 had stable disease. The overall tumour size reduction was 25% (0–62.5%), and there was no tumour progression. Eleven patients underwent tumour resection, and all had R0 resection. After a median followup of 48 months, 4-year OS and DFS were 100% and 64%, respectively. Conclusion. This prospective trial showed that one year of neoadjuvant imatinib in advanced GIST is safe and associated with high rate of complete microscopic resection. It is not associated with increased resistance, progression, or complication rates.

Modern treatment of gastric gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GIST) are rare mesenchymal smooth muscle sarcomas that can arise anywhere within the gastrointestinal tract. Sporadic mutations within the tyrosine kinase receptors of the interstitial cells of Cajal have been identified as the key molecular step in GIST carcinogenesis. Although many patients are asymptomatic, the most common associated symptoms include: abdominal pain, dyspepsia, gastric outlet obstruction, and anorexia. Rarely, GIST can perforate causing life-threatening hemoperitoneum. Most are ultimately diagnosed on cross-sectional imaging studies (i.e., computed tomography and/or magnetic resonance imaging in combination with upper endoscopy. Endoscopic ultrasonographic localization of these tumors within the smooth muscle layer and acquisition of neoplastic spindle cells harboring mutations in the c-KIT gene is pathognomonic. Curative treatment requires a complete gross resection of the tumor. Both open and minimally invasive operations have been shown to reduce recurrence rates and improve long-term survival. While there is considerable debate over whether GIST can be benign neoplasms, we believe that all GIST have malignant potential, but vary in their propensity to recur after resection and metastasize to distant organ sites. Prognostic factors include location, size (i.e., > 5 cm), grade (> 5-10 mitoses per 50 high power fields and specific mutational events that are still being defined. Adjuvant therapy with tyrosine kinase inhibitors, such as imatinib mesylate, has been shown to reduce the risk of recurrence after one year of therapy. Treatment of locally-advanced or borderline resectable gastric GIST with neoadjuvant imatinib has been shown to induce regression in a minority of patients and stabilization in the majority of cases. This treatment strategy potentially reduces the need for more extensive surgical resections and increases the number of patients eligible for curative therapy. The modern surgical treatment of gastric GIST combines the novel use of targeted therapy and aggressive minimally invasive surgical procedures to provide effective treatment for this lethal, but rare gastrointestinal malignancy.

Clinical outcomes of gastrointestinal stromal tumor in southern Thailand

AIM: To review a single institutional experience in clinical management of gastrointestinal stromal tumors (GIST) and analyze for factors determining treatment outcome.

METHODS: Clinicopathological data of patients with a diagnosis of GIST who were treated at our institute during November 2004 to September 2009 were retrospectively reviewed.

RESULTS: Ninety-nine cases were included in the analysis. Primary tumor sites were at the stomach in and small bowel in 44% and 33%, respectively. Thirty-one cases already had metastasis at presentation and the most common metastatic site was the liver. Sixty-four cases (65%) were in the high-risk category. Surgical treatment was performed in 77 cases (78%), 3 of whom received upfront targeted therapy. Complete resection was achieved in 56 cases (73% of operative cases) and of whom 27 developed local recurrence or distant metastasis at a median duration of 2 years. Imatinib was given as a primary therapy in unresectable cases (25 cases) and as an adjuvant in cases with residual tumor (21 cases). Targeted therapy gave partial response in 7 cases (15%), stable disease in 27 cases (57%) and progressive disease in 13 cases (28%). Four-year overall survival was 74% (95% CI: 61%-83%). Univariate survival analysis found that low-risk tumor, gastric site, complete resection and response to imatinib were associated with better survival.

CONCLUSION: The overall outcomes of GIST can be predicted by risk-categorization. Surgery alone may not be a curative treatment for GIST. Response to targeted therapy is a crucial survival determinant in these patients.

Efficacy of PET-CT for predicting the malignant potential of gastrointestinal stromal tumors

PURPOSES

Gastrointestinal stromal tumor (GIST) is the most common sarcoma of the intestinal tract. The risk category is usually determined by tumor size and mitotic count, but accurate preoperative diagnosis of GIST is very difficult. The purpose of this study is to evaluate the efficacy of positron emission tomography (PET)-CT for predicting the malignant potential of gastrointestinal stromal tumors.

METHODS

Ten patients with GIST who underwent a preoperative PET-CT examination were divided into two groups by risk category, and various factors were compared between the two groups. The relationships between the maximum standardized uptake value (SUVmax) and GIST parameters were examined.

RESULTS

Patients were classified into two groups by their risk category: (low/intermediate-risk or high-risk). The SUVmax was significantly higher in the high-risk group (11.0 ± 3.04) than in the low/intermediate-risk group (2.1 ± 1.5). The Ki67 labeling index was also significantly higher in the high-risk group (8.63 ± 6.2) than in the low/intermediate-risk group (1.75 ± 0.52). There was a significant correlation between the Ki67 labeling index and the SUVmax (p = 0.028) and between the mitotic index and the SUVmax (p = 0.029).

CONCLUSIONS

PET-CT can predict malignant potential. Cases with a SUVmax of over 5 may have malignant potential.

Effects of endoplasmic reticulum stressors on maturation and signaling of hemizygous and heterozygous wild-type and mutant forms of KIT

Gain of function mutations of KIT are frequent in some human tumors, and are sensible to tyrosine kinase inhibitors. In most tumors, oncogenic mutations are heterozygous, however most in vitro data of KIT activation have been obtained with hemizygous mutation. This study aimed to investigate the maturation and activation of wild-type (WT) and mutant (M) forms of KIT in hemizygous and heterozygous conditions. WT and two types of exon 11 deletions M forms of human KIT were expressed in NIH3T3 cell lines. Membrane expression of KIT was quantified by flow cytometry. Quantification of glycosylated forms of KIT and phosphorylated forms of AKT and ERK were performed by western blot. Simultaneous activation of WT KIT and treatment with endoplasmic reticulum (ER) inhibitors, tunicamycin or brefeldin A induced a complete inhibition of membrane expression of the 145 kDa form of KIT. By contrast activation or ER inhibitors alone, only partly inhibited this form. ER inhibitors also inhibited KIT activation-dependent phosphorylation of AKT and ERK1/2. Brefeldin A induced a complete down regulation of the 145 kDa form in hemizygous M, and induced an intra-cellular accumulation of the 125 kDa form in WT but not in hemizygous M. Heterozygous cells had glycosylation and response to ER inhibitors patterns more similar to WT than to hemizygous M. Phosphorylated AKT was reduced in hemizygous cells in comparison to WT KIT cells and heterozygous cells, and in the presence of brefeldin A in all cell lines. Effects of ER inhibitors are significantly different in hemizygous and heterozygous mutants. Differences in intra-cellular trafficking of KIT forms result in differences in downstream signaling pathways, and activation of PI3K/AKT pathway appears to be tied to the presence of the mature 145 kDa form of KIT at the membrane surface.

Gastrointestinal stromal tumor of the rectum: results of surgical and multimodality therapy in the era of imatinib

BACKGROUND

The rectum is a rare site of gastrointestinal stromal tumor (GIST), and factors determining long-term outcome remain unclear. In a population study, we assessed the outcome of rectal GIST patients treated at two referral centers.

METHODS

A total of 39 patients diagnosed with rectal GIST between January 2002 and December 2010 were identified in prospective databases. Tumor and patient characteristics, treatment details, and outcome were evaluated. Median follow-up was 41 (3-110) months.

RESULTS

A male predominance was noticed (M/F = 29/10). Median age was 53 years (range, 32-80 years). The cohort included, of 39 patients, 12 low-risk, 26 high-risk, and 1 with M1 disease. Of 38 patients with nonmetastatic disease, 36 underwent surgery as transabdominal (15 of 36) or local (21 of 36) resection. There were 21 patients who received preoperative and/or postoperative imatinib treatment. Patients with preoperative imatinib (16 of 36) had a significantly higher rate of R0 resections (p = .02). Five patients developed local recurrences. All of them had undergone local tumor excision with positive margins and without perioperative imatinib. Also, five patients suffered from distant metastases. All belonged to the high-risk group and underwent tumor surgery (3 R0, 2 R1) without receiving perioperative imatinib. A total of three patients died of disease. Perioperative imatinib was associated with improved local disease-free, disease-free, and overall survival (p < .01, p < .01, and p = .03, respectively). Local disease-free survival was significantly improved by negative resection margins (p < .01).

CONCLUSIONS

Complete resection is recommended to achieve local disease control. Preoperative imatinib was associated with improved surgical margins. Perioperative imatinib was associated with improved local disease-free, disease-free, and overall survival.

Gastrointestinal tumors of the colon and rectum

Gastrointestinal stromal tumors (GISTs) of the colon and rectum are the most common mesenchymal tumors of the gastrointestinal tract. GISTs of the colon and rectum constitute ~5% of all cases. Although colorectal GISTs can be small and found incidentally, the majority appear to be high risk and carry a significant likelihood of recurrent and metastatic disease. Surgery remains the mainstay of treatment for primary disease. There is now considerable interest in GISTs because they can be treated effectively with targeted molecular therapies, specifically tyrosine kinase inhibitors (TKIs), such as imatinib mesylate and sunitinib malate. GISTs are best treated by a multidisciplinary team comprised of the surgeon, medical oncologist, pathologist, and radiologist in the initial evaluation, management, and in continued follow-up. Increasing the number of resectable cases through pharmacologic debulking, optimizing the timing of surgery and organ preservation, reducing recurrence and surgical morbidity, prolonging survival, and possibly enhancing response to imatinib through surgical cytoreduction are all potential benefits of multidisciplinary management.

Gastrointestinal stromal tumor

Gastrointestinal stromal tumor has received a lot of attention over the last 10 years due to its unique biologic behavior, clinicopathological features, molecular mechanisms, and treatment implications. GIST is the most common mesenchymal neoplasm in the gastrointestinal tract and has emerged from a poorly understood and treatment resistant neoplasm to a well-defined tumor entity since the discovery of particular molecular abnormalities, KIT and PDGFRA gene mutations. The understanding of GIST biology at the molecular level promised the development of novel treatment modalities. Diagnosis of GIST depends on the integrity of histology, immunohistochemistry and molecular analysis. The risk assessment of the tumor behavior relies heavily on pathological evaluation and significantly impacts clinical management. In this review, historic review, epidemiology, pathogenesis and genetics, diagnosis, role of molecular analysis, prognostic factor and treatment strategies have been discussed.

Gastrointestinal stromal tumors: the role of the gastroenterologist in diagnosis and risk stratification

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors that are best classified as sarcomas with variable aggressiveness. They are typically treated with surgical resection and adjuvant tyrosine kinase inhibitors or, for advanced/metastatic GISTs, with tyrosine kinase inhibitors alone. Gastroenterologists are often the first to detect GISTs and are, therefore, tasked with diagnosis and facilitation of early intervention. Diagnostic tools including various imaging techniques such as endoscopic ultrasound (EUS) and EUS-assisted tissue sampling are critical for an accurate diagnosis. In the case of small tumors, EUS-assisted resection or ligation techniques to treat asymptomatic small tumors have been described. This paper reviews current evidence for the diagnosis and management of GISTs, with an emphasis on the role of the gastroenterologist.

Personalized therapy: prognostic factors in gastrointestinal stromal tumor (GIST)

Over the last decade, considerable progress has been made in gastrointestinal stromal tumor (GIST) with respect to determining prognosis and therapy. Here, we will summarize some of the major developments and how they have led to an increased use of personalized treatment in GIST.

Genomic Grade Index predicts postoperative clinical outcome of GIST

BACKGROUND

Prognosis of localised gastrointestinal stromal tumour (GIST) is heterogeneous, notably for patients with AFIP intermediate or high risk of relapse, who are candidates to adjuvant imatinib. We hypothesised that gene expression profiles might improve the prognostication and help to refine the indications for imatinib.

METHODS

We collected gene expression and histoclinical data of 146 pre-treatment localised GIST samples treated with surgery alone. We searched for a gene expression signature (GES) predictive for relapse-free survival (RFS) and compared its performances to that of three published prognostic proliferation-based GES (Genomic Grade Index (GGI), 16-Kinase, and CINSARC) and AFIP classification. We also analysed a data set from 28 patients with advanced GIST treated with neo-adjuvant imatinib.

RESULTS

We identified a 275-gene GES (gene expression signature) predictive of RFS in a learning set and validated its robustness in an independent set. However, the GGI outperformed its prognostic performances, and those of the two other signatures and the AFIP intermediate-risk classification in two independent tests sets in uni- and multivariate analyses. Importantly, GGI could split the AFIP intermediate/high-risk samples into two groups with different RFS. Genomic Grade Index 'high-risk' tumours were more proliferative and genetically unstable than 'low-risk' tumours, and more sensitive to imatinib.

CONCLUSION

GGI refines the prediction of RFS in localised GIST and might help tailor adjuvant imatinib.

Gastrointestinal stromal tumors: case series of 29 patients defining the role of imatinib prior to surgery

BACKGROUND

The aim of this study was to assess the role of neoadjuvant imatinib in redefining treatment for gastrointestinal stromal tumors (GISTs).

METHODS

A total of 76 patients were reviewed. Among them, 29 patients who were administered neoadjuvant imatinib for borderline resectable and locally advanced GISTs followed by surgery were analyzed. Adjuvant imatinib was administered based on risk stratification.

RESULTS

The median age of the neoadjuvant imatinib group was 51 years. The median duration of neoadjuvant imatinib administration was 8.5 months. The response rate with neoadjuvant imatinib was 79.3%. Five patients, initially considered to have locally unresectable lesions, ultimately underwent resection (three R0, two R2). Another three patients, who had M1 disease, underwent R2 resection (due to the presence of metastasis) with complete resection of the primary lesion. In 19 patients, who would have originally required extensive surgery, underwent conservative surgery (R0). In two patients, neoadjuvant imatinib did not influence the final procedure. The postoperative complication rate was 13.8%, and there were no postoperative deaths. There was one locoregional recurrence and two cases of distant metastasis. The 1-, 2-, and 3-year overall survivals were each 100%.

CONCLUSIONS

Neoadjuvant imatinib for locally advanced GISTs is a safe concept for downsizing, improving resectability, and aiding organ-preserving surgery. It also improves the chance of long-term survival. Surgery, however, remains the cornerstone of curative treatment of GISTs even after neoadjuvant imatinib.

Primary leiomyosarcomas of the gastrointestinal tract in the post-gastrointestinal stromal tumor era

Most mesenchymal neoplasms of the gastrointestinal tract are currently classified as gastrointestinal stromal tumors (GIST). Gastrointestinal stromal tumors are diagnosed by immunopositivity for CD117, CD34, and DOG1.1, with or without molecular analyses. According to the World Health Organization classification, the diagnosis of primary leiomyosarcomas of the gastrointestinal tract is so rare that there are no significant data on demographic, clinical, or gross features of this tumor. A comprehensive literature search was performed to identify gastrointestinal leiomyosarcomas. Searches were limited to the past 12 years because definitive tools to differentiate leiomyosarcomas from GIST were introduced in the late 1990s. Cases were included only if convincing data were presented. Six cases of esophageal leiomyosarcoma and 5 cases of gastric leiomyosarcoma were confirmed. Furthermore, 26 cases of leiomyosarcoma of the small bowel, 11 cases of the colon, and 8 cases arising in the rectum were identified. Finally, 28 cases of infantile and adolescent leiomyosarcoma were reviewed. Although survival analysis is precluded by small case numbers and limited survival data availability, the trend identifies that increased size and mitotic activity portends to a worse prognosis in small bowel leiomyosarcomas. Colonic leiomyosarcomas appear to be aggressive tumors, regardless of tumor size and mitotic activity. Rectal leiomyosarcomas present as smaller tumors with favorable prognosis. Leiomyosarcomas in post-GIST era are rare tumors of the gastrointestinal tract with distinctive clinicopathologic characteristics. Owing to different treatment options, it is necessary to accurately differentiate these from GIST, using a combination of histologic appearance, presence of smooth muscle antigens, and absence of specific GIST immunomarkers.

Clinical features and treatment of gastrointestinal stromal tumors: Recent advances

Gastrointestinal stromal tumors (GISTs) are the most common gastrointestinal mesenchymal tumors. The development of molecular biology, pathology and clinical medicine in recent years has deepened our understanding of GISTs. The combination of traditional surgery and molecular targeted drugs is particularly important for the treatment of GISTs. Multi-target and multi-kinase inhibitors such as imatinib and sunitinib have been used for the treatment of unresectable and recurrent GISTs. This paper provides a brief review of gene analysis, pathological characteristics, operational and adjuvant therapy of GISTs.

The role of surgery in the multidisciplinary management of patients with localized gastrointestinal stromal tumors

Surgical resection of localized gastrointestinal stromal tumors (GISTs) is associated with recurrence rates of approximately 50% at 5 years of follow-up. The introduction of tyrosine kinase inhibitors, such as imatinib, improved overall survival rates in advanced disease, while in the adjuvant setting, improved recurrence-free survival following resection of high-risk GIST. The demonstration of the clinical benefit of tyrosine kinase inhibitors in both the metastatic and adjuvant settings generated interest in neoadjuvant approaches for patients with operable locally advanced disease, particularly in difficult anatomic locations. The potential impact of tumor downsizing in areas such as the gastroesophageal junction, the duodenum or the rectum, on the extent of surgical resection and morbidity is real. The ongoing research regarding neoadjuvant therapy, the duration of adjuvant therapy and the optimal means by which to risk stratify patients with GIST continues to keep the treatment of this disease at the forefront of personalized cancer care.

Tyrosine-kinase mutations in c-KIT and PDGFR-alpha genes of imatinib naïve adult patients with gastrointestinal stromal tumours (GISTs) of the stomach and small intestine: relation to tumour-biological risk-profile and long-term outcome

BACKGROUND

The identification of activating mutations in either c-KIT cell surface growth factor receptor or platelet-derived growth factor receptor alpha (PDGFRA) has lead the way for the development of novel agents that selectively inhibit key molecular events in gastrointestinal stromal tumour (GIST) pathogenesis. The aim of this study was to investigate the role of c-KIT and PDGFRA gene mutations in primary resectable, imatinib naïve GISTs located in the stomach and small intestine.

METHODS

All adult patients with GIST located in either stomach or small intestine who underwent surgical resection without prior imatinib (Glivec) treatment were included. DNA extraction and mutational analysis were performed. Mutational analyses were performed for c-KIT (exons 9, 11, 13, and 17) and the PDGFRA genes (exons 12, 14 and 18). Clinical and pathological parameters were analyzed in relation to the mutations in c-KIT and PDGFRA.

RESULTS

A total of 38 patients who underwent surgery for GIST located in either the stomach (n = 24) or in the small intestines (n = 14) were included. Mutations were found in 31 of 38 (81.6 %) patients, with 24 (63.2 %) located in c-KIT and 7 (18.4 %) in the PDGRFA exons, respectively. Seven patients (18.4 %) were wildtype (WT). The most common mutation was in c-KIT exon 11. Incidentally found GISTs were significantly smaller (size >5 cm in 15 % for incidental vs. 71 % for symptomatic; OR of 13.4, 95 % CI 2.3-76.5; P = 0.001) and had lower mitotic rate (0 % for incidental vs. 44 % of the symptomatic; OR 0.52, 95 % CI 0.36-0.75; P = 0.005). Accordingly, the Fletcher grade was significantly better for incidental cases, with most having very low or low risk (85 %) in contrast to 19 of 25 (76 %) symptomatic cases showing moderate to high-risk features (OR 17.4, 95 % CI 2.98-101.7; P < 0.001). However, the distribution of c-KIT, PDGFRA and WT was not differently distributed between incidental and symptomatic GISTs. Long-term survival up to 25 years (median: 8 years) was best determined by Fletcher risk-score in the multivariate model (HR 14.1, 95 % CI 1.7-114.5; p = 0.013).

CONCLUSIONS

Long-term survival in resected GISTs of the stomach and small intestine is best determined by Fletcher risk-score. Mitotic activity appears related to tumour size and young age at onset. Mutational status did not influence the clinical or tumour-specific features in this cohort.

Pathology of gastrointestinal stromal tumors

Gastrointestinal stromal tumor (GIST) is a well recognized and relatively well understood soft tissue tumor. Early events in GIST development are activating mutations in KIT or PDGFRA, which occur in most GISTs and encode for mutated tyrosine receptor kinases that are therapeutic targets for tyrosine kinase inhibitors, including imatinib and sunitinib. A small minority of GISTs possessing neither KIT nor PDGFRA mutations may have germline mutations in SDH, suggesting a potential role of SDH in the pathogenesis. Immunohistochemical detection of KIT, and more recently DOG1, has proven to be reliable and useful in the diagnosis of GISTs. Because current and future therapies depend on pathologists, it is important that they recognize KIT-negative GISTs, GISTs in specific clinical contexts, GISTs with unusual morphology, and GISTs after treatment. This review focuses on recent developments in the understanding of the biology, immunohistochemical diagnosis, the role of molecular analysis, and risk assessment of GISTs.

Current management and prognostic features for gastrointestinal stromal tumor (GIST)

Stromal or mesenchymal neoplasms affecting the gastrointestinal (GI) tract have undergone a remarkable evolution in how they are perceived, classified, approached, diagnosed and managed over the last 30 years. Gastrointestinal stromal tumors (GIST) account for approximately 1% to 3% of all malignant GI tumors. The clinical features can vary depending on the anatomic location, size and aggressiveness of the tumor. Metastatic GIST represents a successful example of molecular targeted therapy. In this comprehensive review, we discuss the epidemiology, clinical features and diagnostic modalities for GIST. We also describe treatment options for early stage, locally advanced and metastatic GIST. Indications for neoadjuvant and adjuvant therapy along with duration of therapy are also explained. A brief discussion of latest biomarkers and updates from recent meetings is also provided.

Gastrointestinal stromal tumor of the rectum with scapular metastasis: a case report

Introduction

Gastrointestinal stromal tumors are rare tumors. They commonly metastasize within the abdominal cavity, particularly to the liver. Less commonly, metastases can be found in the bone.

Case presentation

We here present a case of metastasis to the scapula in a 54-year-old Caucasian male patient with an advanced gastrointestinal stromal tumor, which was subsequently successfully treated with resection and sunitinib.

Conclusion

The present study is, to the best of our knowledge, the second to describe scapular metastasis of a gastrointestinal stromal tumor. Our patient was treated by scapulectomy. The overwhelming majority of scapular tumors are metastases that arise from soft tissue, hepatocellular and thyroid tumors. Gastrointestinal stromal tumor metastasis occurs rarely. Scapular surgery can successfully provide local control of the disease. After the surgery, patients should continue with medical treatment.

Current management of gastrointestinal stromal tumors--a comprehensive review

BACKGROUND

Gastrointestinal stromal tumors (GISTs) comprise < 1% of all gastrointestinal (GI) tumors, but GISTs are the most common mesenchymal tumors of the GI tract. Dramatic changes in clinical practice have been observed in the last decade. This review highlights the overall management of GIST and its recent developments.

METHOD

We identified literature by searching Medline and PubMed from January 1995 to December 2011 using the keywords "gastrointestinal stromal tumors", "GIST", "imatinib" and "tyrosine kinase inhibitor". Additional papers were identified by a manual search of the references from the key articles. There were no exclusion criteria for published information to the topics.

RESULTS

For localized primary GISTs, surgical resection is the mainstay of therapy. The 5-year survival rate after complete resection of GISTs is approximately 50%-65%. Many factors including tumor size, mitotic rate, tumor location, kinase mutational status and occurrence of tumor rupture have been extensively studied and proposed to be predictors of survival outcomes. Adjuvant imatinib is proposed as an option for those patients with a substantial risk of relapse. Unresectable metastatic or recurrent GIST can be treated with a tyrosine kinase inhibitor, imatinib, with a remarkable response (50%-70%) and prolonged survival (median progression-free survival: 18-20 months; median overall survival: 51-57 months). The standard approach in the case of tumor progression on 400 mg once per day is to increase the imatinib dose to 400 mg twice per day as permitted by toxicity. Use of a second-line targeted agent, sunitinib, in patients with advanced GIST who fail (or are intolerant of) imatinib therapy is advised.

CONCLUSION

Treatment for GISTs has become increasingly complex because of the growing understanding of its biology. A multidisciplinary team that includes radiologists, medical oncologists, pathologists, and surgeons is paramount for the effective treatment of GIST.

Integrating bioinformatics and clinicopathological research of gastrointestinal stromal tumors: identification of aurora kinase A as a poor risk marker

BACKGROUND

For completely resected primary gastrointestinal stromal tumors (GISTs), mitotic rate, tumor size, and tumor location are important risk factors for recurrence. However, molecular markers for recurrence are still lacking.

METHODS

We reanalyzed GIST gene expression profile GSE8167 available from the Gene Expression Omnibus (GEO) and confirmed the prognostic influence of one selected gene, aurora kinase A (AURKA), in another cohort of 142 patients using immunohistochemistry (IHC).

RESULTS

Thirty-two cases in GSE8167 were classified into two risk groups with distinct recurrence-free survival (RFS) and expression profiles using modified criteria of Miettinen et al. from the Armed Forces Institute of Pathology (AFIP-Miettinen). AURKA was among the 19 genes common to the top 50 features of the high-risk phenotype and a 67-gene signature called the complexity index in sarcomas. AURKA was significantly overexpressed in the high-risk group, and patients with high AURKA expression had significantly worse RFS than those with low expression. In the IHC-validated cohort, AURKA expression was significantly higher in nongastric tumors than in gastric tumors and was significantly correlated with AFIP-Miettinen risk group. Univariate analysis showed that RFS was significantly influenced by tumor size, mitotic count, AFIP-Miettinen risk group classification, and AURKA expression. However, only tumor size (P = 0.017), mitotic count (P = 0.007), and AURKA expression (P = 0.039) were identified as independent unfavorable prognostic factors for RFS in multivariate analysis.

CONCLUSIONS

By integrating bioinformatics and clinicopathological studies, AURKA was identified as a marker for high-risk GIST.