Colorectal Gastrointestinal Stromal Tumors Research Articles

Effect of tumor location on the efficacy of chemotherapy for gastrointestinal stromal tumors.

790 Background: Gastrointestinal stromal tumors (GISTs) arise from multiple sites within the gastrointestinal tract. Since the introduction of imatinib in 2002, patients have seen improved overall survival. However, a recent National Cancer Database (NCDB) study suggested no survival benefit to adjuvant imatinib for colorectal GIST patients. Another recent study showed that small bowel GISTs have larger median tumor size and higher incidence of tumors with at least 5 mitoses compared to gastric GISTs. These findings suggest a differential tumor biology for GISTs arising from different primary tumor sites, potentially conferring differential response to imatinib. In this NCDB study, we compare overall survival outcomes with and without chemotherapy, stratifying by primary tumor site. Methods: We queried the NCDB from 2004-2018 for patients with GIST histology. We excluded patients with age <40, age>80, high comorbidity score, and patients who received additional therapy other than surgery or chemotherapy. Of the 22,846 patients meeting criteria for our study, 27 patients had tumors originating from the anus, 454 from the colon, 173 from the esophagus, 15,296 from the stomach, 556 from the rectum, 32 from the rectosigmoid junction, and 6,308 from the small intestine. 8,983 (39%) received chemotherapy. Treatment with chemotherapy was used to extrapolate response to imatinib, the mainstay of treatment. Results: Cox proportional hazards analysis demonstrated increased hazard of death for chemotherapy, increasing age, and comorbidity score of 1. Positive predictive factors for survival included female sex and later year of diagnosis. For anal, esophageal, gastric, and rectosigmoid GIST patients, there was no statistically significant overall survival benefit for any treatment modality. For colonic GISTs, neoadjuvant chemotherapy combined with surgery improved overall survival. For rectal GISTs, adjuvant chemotherapy with surgery also provided survival benefit. For small intestinal GISTs, surgery alone or surgery with neoadjuvant, adjuvant, or both neoadjuvant and adjuvant chemotherapy improved overall survival. Conclusions: While our study is retrospective and limited as a NCDB study, our Kaplan-Meier survival analysis demonstrated survival benefit for chemotherapy only in patients with colon, rectal, or small intestinal GIST tumors. Our Cox proportional analysis demonstrated an overall negative survival impact for chemotherapy. These findings lend further support to the idea that differential tumor biology at each primary site may lead to differential response to imatinib. Overall, our study provides rationale for further investigating the heterogeneity of GIST tumor microenvironments, as these differences could contribute to the differential treatment outcomes.

Development and validation of a prognostic model to predict the prognosis of patients with colorectal gastrointestinal stromal tumor: A large international population-based cohort study.

Colorectal gastrointestinal stromal tumors (GISTs), mesenchymal malignancy, only accounts for about 6% of GISTs, but prognosis is generally poor. Given the rarity of colorectal GISTs, the prognostic values of clinicopathological features in the patients remain unclear. Nomograms can provide a visual interface to help calculate the predicted probability of a patient meeting a specific clinical endpoint and communicate it to the patient. We included a total of 448 patients with colorectal GISTs diagnosed between 2000 and 2019 from the Surveillance, Epidemiology, and End Results (SEER) database. For nomogram construction and validation, patients in the SEER database were divided randomly into the training cohort and internal validation cohort at a ratio of 7:3, while 44 patients with colorectal GISTs from our hospital patient data set between 2010 to 2016 served as the external validation cohort. The OS curves were drawn using the Kaplan-Meier method and assessed using the log-rank test. And, Fine and Gray's competing-risks regression models were conducted to assess CSS. We performed univariate and multivariate analyses to select prognostic factors for survival time and constructed a predictive nomogram based on the results of the multivariate analysis. Through univariate and multivariate analyses, it is found that age, primary site, SEER stage, surgery, and tumor size constitute significant risk factors for OS, and age, primary site, histological grade, SEER stage, American Joint Committee for Cancer (AJCC) stage, surgery, and tumor size constitute risk factors for CSS. We found that the nomogram provided a good assessment of OS and CSS at 1-, 3- and 5- year in patients with colorectal GISTs. The calibration plots for the training, internal validation and external validation cohorts at 1-, 3- and 5- year OS and CSS indicated that the predicted survival rates closely correspond to the actual survival rates. We constructed and validated an unprecedented nomogram to predict OS and CSS in patients with colorectal GISTs. The nomogram had the potential as a clinically predictive tool for colorectal GISTs prognosis, and can be used as a potential, objective and additional tool for clinicians in predicting the prognosis of colorectal GISTs patients worldwide. Clinicians could wield the nomogram to accurately evaluate patients' OS and CSS, identify high-risk patients, and provide a baseline to optimize treatment plans.

Prognostic Factors and Management of Colorectal Gastrointestinal Stromal Tumors

Abstract Introduction The gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the gastrointestinal tract. Even though it can be found in any location of the digestive tract, the colorectal GIST is rare. With this study, we aim to review the current knowledge regarding the prognosis and management of colorectal GIST. Methods A literature search was conducted in PubMed, and 717 articles were collected. After analyzing these studies, 60 articles were selected to use in this review. Results The mitotic index, as well as tumor size and location were identified as good discriminators of prognosis in various studies. Surgery remains the only curative therapy for potentially resectable tumors. However, even after surgical resection, some patients develop disease recurrence and metastasis, especially those with high-risk tumors. Therefore, surgical resection alone might be inadequate for the management of all colorectal GISTs. The discovery of GIST's molecular pathway led to a shift in its therapy, insofar as tyrosine kinase inhibitors became part of the treatment schemes for this tumor, revolutionizing the treatment's outcome and prognosis. Discussion/Conclusion The controversy concerning colorectal GIST prognosis and treatment can be, in part, attributed to the limited number of studies in the literature. In this review, we gathered the most recent knowledge about the prognosis and management of GIST in this rare location and propose two algorithms for its approach. Lastly, we highlight the importance of an individualized approach in the setting of a multidisciplinary team.

Abstract 1191: Differences in gene mutation characteristics of gastric, intestinal and colorectal stromal tumors

Abstract Background: Gastrointestinal stromal tumors (GIST), which were thought to originate from interstitial cells of Cajal,is the most common malignant mesenchymal neoplasm, and account for 1%-3% of digestive tract tumors. Drug development in GIST has successfully utilized the KIT/PDGFRA oncogenic mutation. At the same time, drug sensitivity and resistance, such as imatinib resistance, is a problem should be paid more attention. We analyzed features of kit/pdgfra mutation in different region GIST of Chinese patients, which will provide reference information for the use of targeted drugs among patients with gastric, intestinal or colorectal stromal tumors. Methods: Tumor samples of 201 HCC patients were consecutively collected in China from January 2018 to June 2020, next generation sequencing (NGS) was performed to detect gene mutation by 3D Medicines, a laboratory accredited by College of American Pathologists (CAP) and Clinical Laboratory Improvement Amendments (CLIA. Results: All these tissue samples were divided as stomach (n=109), small intestine (n=79), colon and the rectum (n=13). The average age of three group were 57, 55 and 50, the proportion of males in gastric, intestinal and colorectal stromal tumor were 64.2% (79/109), 60.8% (48/79) and 61.5%(8/13), respectively. NGS analysis showed that, frequency of kit were 71.5% (78/109), 83.5% (66/79) and 61.5% (8/13), among witch, mutation of exon 9 were 1.8%(2/109), 27.8% (22/79), 30.7% (4/13), and exon 11 were 66.1%(72/109), 53.2%(42/79), 30.8%(4/13); frequency of pdgfra were 14.7%(16/109), 3.8%(3/79) and 7.7%(1/13), and mutation frequency of pdgfra exon 18 were 11.9% (13/109), 1.3%(1/79), 7.7%(1/13). Conclusions: GIST is more inclined to occur in male. kit was the main mutation in GIST, however, only 1.8% of gastric GIST carry exon 9 mutations, a large proportion (66.1% and 53.2%) of gastric and intestinal GISTs carry exon 11 mutations. Besides, more mutation of pdgfra happened in gastric GIST than intestinal and colorectal GISTs. These results demonstrate that GIST occurred in different location may show different sensitivity or resistance to drugs targeting KIT/PDGFRA signals. Citation Format: Qian Wang, Hushan Zhang, Sihui Zhao, Jianxun Wang, Ning Ma, Jun Zhu. Differences in gene mutation characteristics of gastric, intestinal and colorectal stromal tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1191.

S1726 A “Low-Risk” Colonic Gastrointestinal Stromal Tumor With Metastatic Features

INTRODUCTION: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumor of the GI tract, yet only make up about 0.1% of colon and rectal tumors. Studies on colonic GISTs are currently limited to case reports and small case series. As a result, risk assessments for malignant potential primarily focus on gastric and small bowel lesions. We present a case of a transverse colon GIST that developed metastatic disease despite having low risk features. CASE DESCRIPTION/METHODS: A 69-year-old male with iron deficiency anemia was referred for endoscopic evaluation. He was asymptomatic with a normal colonoscopy 4 years prior. His EGD found H. Pylori-associated chronic active gastritis and his colonoscopy revealed a 3-to 4cm mass in the transverse colon with central ulceration (Figure 1). Histopathology showed marked spindle cell proliferation, positive for CD-117 and CD-34 stain, confirming gastrointestinal stromal tumor. He underwent right hemicolectomy demonstrating the 3.5 cm GIST, negative margins and 33 negative regional lymph nodes. Surgical pathology revealed 4 mitoses/50 HPF, positive CD117 and DOG1 stains. Follow-up PET CT scan found ascites, bilateral pleural effusions, and focal activity in a cardiophrenic lymph node consistent with metastatic disease. Oncology is planning to initiate imatinib therapy. DISCUSSION: As colorectal GISTs tends to primarily occur in the rectum, this finding in the transverse colon was rare. Their presentation is often due to vague abdominal pain, anemia, or incidental finding on screening colonoscopy. Surgical resection is definitive therapy with imatinib used as adjuvant therapy for those with high risk of recurrence. The NCCN estimates risk for metastatic rate between 1.9%-8-5% for tumor sizes between 2-5cm and < 5 mitoses/50 HPFs. Given the uncommon presentation, specific risk assessments for malignant progression or reoccurrence for colonic GISTs are limited. While gastric and small bowel GISTS are labeled low-risk for metastasis based on a small tumor size and low mitotic rate of < 5/50 HPF, our case displays the aggressive nature of colonic GISTs despite meeting these criteria. Colorectal GISTs should be treated as high risk lesions despite size and mitotic rate.Figure 1.: Colonoscopic view of GIST.Figure 2.: H&E stain demonstrating spindle cell architecture.Figure 3.: PET with cardiophrenic lymph node involvement.

Gastrointestinal stromal tumors of the colon and rectum.

Gastrointestinal stromal tumors (GISTs) are rare neoplasms, colorectal location being met in less than 5% of cases. Knowledge about this site related particularities are limited. The aim of this study is to present our experience with colorectal GISTs between 2005 and 2018 from the clinical, morphological, and immunohistochemical perspectives, with emphasis on prognostic factors. From a total of 203 gastrointestinal stromal tumors registered, 12 were colorectal (6%). The number of colonic tumors surpassed that of the rectum (9 : 3) and on the right side were registered more cases than on the left side (6/3). 9 were primary tumors and 3 were recurrences. Men and women were represented equally and the age range was between 22 and 76. Tumor dimensions varied between 0.5 and 14 cm. Microscopically, spindle cell type was dominant. Mitotic rate was variable between 1 and 115/50HPFs. Accordingly, for primary tumors progression risks were assigned (low risk: 2 cases, intermediate risk: 3 cases and high risk: 4 cases). All GISTs were CD117 and DOG1 positive. Four of the patients died of the disease.

Minimally invasive surgery for gastrointestinal stromal tumors--pursuing the trivial, or striving for perfection

Complete surgical resection is the main treatment for gastrointestinal stromal tumor (GIST). However, GIST is crisp with rich blood supply, and prone to rupture with improper handling, leading to intra-abdominal hemorrhage and tumor cell dissemination. With the development of technology and equipment, minimally invasive surgery is getting mature. However, according to a phase III, multicenter, randomized controlled trial published in the New England Journal of Medicine in November 2018, open surgery was superior to minimally invasive surgery for early cervical cancer, which warned us that the application of minimally invasive surgery in GIST should be understood dialectically. The general principle of minimally invasive surgery of GIST is avoiding tumor rupture, despite the different location and decision-making according to tumor location. For gastric GIST, minimally invasive surgery should be performed with tumor locating at the greater curvature or anterior wall of the stomach, and with a diameter less than 5 cm. Small intestinal GIST is more malignant and not recommended to undergo minimally invasive surgery, but the technique can be used to expose and locate the tumor. Colorectal GIST is rare but highly malignant, therefore open surgery should be the first choice. In fact, minimally invasive surgery for rectal GIST has certain advantages such as better visualization compared to open surgery. GIST in non-appropriate location, such as the esophagogastric junction, pylorus, and duodenum, should be treated with caution because of its close relationship with organ function. The general principle of GIST treatment is to completely remove the tumor while retaining organ function. The application of minimally invasive surgery should not cause extra damage to organ function or increase the risk of tumor rupture. Endoscopic treatment of GIST still lacks high-quality evidence-based studies. The application of minimally invasive surgery should be conservative. The purpose of performing minimally invasive surgery is not the technique itself, but to minimize the injuries to tissue and organs. In conclusion, we should perform minimally invasive surgery for appropriate patients cautiously on the basis of complete resection and function preservation.

The Impact of Imatinib on Survival and Treatment Trends for Small Bowel and Colorectal Gastrointestinal Stromal Tumors

BackgroundThe aim of this study is to assess treatment trends and overall survival (OS) in small bowel (SB) and colorectal (CR) gastrointestinal stromal tumors (GIST) with respect to the introduction of imatinib in 2008. MethodsPatients diagnosed with SB and CR GIST were identified from the National Cancer Database (2004–2015). The primary outcome was 5- and 10-year OS. Patients were stratified by tumor site, time period (before and after imatinib), and treatment type. OS was analyzed using Kaplan-Meier survival curves, log-rank test, and Cox proportional hazards models. ResultsA total of 8441 cases were included (SB 81.66%; CR 18.34%). Radical resection was the most common treatment (SB 42.33%; CR 38.69%). The addition of chemotherapy to radical resection for SB GIST increased between the two time periods (31.76 to 40.43%; p < 0.001), and was associated with improved unadjusted and adjusted OS (2009–2015: adjusted HR [AHR] 0.73, 95% CI 0.59–0.89, p = 0.002). Patients with SB GIST had better 5- and 10-year OS compared with CR (SB 69.83% and 47.68%; CR 61.33% and 45.39%; p < 0.001), even after stratifying by treatment type and tumor size and adjusting for other factors (SB 5-year AHR 1.35, 95% CI 1.19–1.53; 10-year AHR 1.23, 95% CI 1.09–1.38; each p < 0.001). ConclusionCR GIST are associated with lower OS than SB GIST. Radical resection is the most common treatment type for both sites. Chemotherapy with radical resection offers better OS in SB GIST, but not in CR GIST. Further studies are needed to assess the biology of CR GIST to explain the worse OS.

The prognostic value of gastrointestinal bleeding in gastrointestinal stromal tumor: A propensity score matching analysis.

Background and objectivesWhether gastrointestinal (GI) bleeding indicates gastrointestinal stromal tumor (GIST) rupture and impacts prognosis is unclear. We examined the prognostic value of GI bleeding in GIST.MethodsPrimary GIST patients with (GB group) or without (NGB group) initial symptoms of GI bleeding were retrospectively studied. Propensity score matching (PSM) was conducted to reduce confounders.ResultsEight hundred patients were enrolled. Male gender [odds ratio (OR) = 1.517, P = 0.011], tumors in the small intestine (OR = 2.539, P < 0.001), and tumor size 5‐10 cm (OR = 2.298, P = 0.004) increased the odds of GI bleeding; age >60 years decreased the odds (OR = 0.683, P = 0.031). After PSM, 444 patients were included (222 in each group). Relapse‐free survival (RFS) (P = 0.001) and overall survival (OS) (P = 0.002) were both superior in the GB group. In subgroup analysis, the GB group achieved a superior RFS (P = 0.005) and OS (P = 0.007) in patients with small intestine GIST, but not stomach or colorectal GIST.ConclusionsGIST patients with age <60, male gender, tumors located in the small intestine, and tumors 5‐10 cm in size had a higher risk of GI bleeding. GIST patients with GI bleeding had a superior RFS and OS. This difference was statistically significant only in small intestine GIST.

744 – Survival and Treatment Trends for Small Bowel and Colorectal Gastrointestinal Stromal Tumors

744 – Survival and Treatment Trends for Small Bowel and Colorectal Gastrointestinal Stromal Tumors

Appropriate Follow-Up Strategies for Gastrointestinal Stromal Tumor Patients Based on the Analysis of Recurrent Interval and Patterns

Background/Aims: Previous studies have proposed risk classifications for patients with gastrointestinal stromal tumor (GIST) after resection and have contributed to the prediction of its prognosis. However, optimal postoperative surveillance has not yet been established. Methods: We retrospectively analyzed data from 115 GIST patients who experienced recurrence after complete resection. The relationships between clinicopathological characteristics and the first recurrence sites, or time to recurrence (TTR), were investigated. We also compared the characteristics between 2 subgroups based on a TTR of ≤5 or >5 years. Results: The first recurrence occurred in the abdomen in 114 of 115 patients (99.1%); one case of esophageal GIST recurred in the lung. Gastric and small intestinal GISTs recurred most frequently in the liver or peritoneum, while the most common recurrences of colorectal GISTs were found to be local. Fourteen patients (12.2%) experienced recurrence after >5 years. Smaller tumors and those categorized as lower risk were significantly more frequent in the TTR >5 years group than in the TTR ≤5 years group. In the TTR >5 years group, local recurrence was the most frequent type of recurrence (42.9%). Conclusion: Based on abdominal examination, postoperative surveillance after complete resection for primary GISTs may be recommended for >5 years.

Diagnostic and treatment strategy for small gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) are considered to be potentially malignant mesenchymal tumors of the gastrointestinal tract. Clinically relevant GISTs are rare; however, subclinical GISTs (mini‐GISTs) (1‐2 cm) and pathologic GISTs (micro‐GISTs) (<1 cm) are frequently reported. Most mini‐GISTs and almost all micro‐GISTs of the stomach may exhibit benign clinical behavior, and only mini‐GISTs with high‐risk features may progress. For this review, a provisional algorithm was used to propose diagnostic and treatment strategies for patients with small GISTs. Because surgery is the only potentially curative treatment, in its application for small GISTs, the principles of sarcoma surgery should be maintained, and cost effectiveness should be considered. Indications for surgery include GISTs measuring ≥2 cm, symptomatic GISTs, and mini‐GISTs with high‐risk features (irregular borders, cystic spaces, ulceration, echogenic foci, internal heterogeneity, and tumor progression during follow‐up); however, a preoperative pathologic diagnosis is infrequently obtained. For small intestinal and colorectal GISTs, surgery is indicated irrespective of size because of their greater malignant potential. Otherwise, mini‐GISTs without high‐risk features, micro‐GISTs, and small submucosal tumors measuring <5 cm without high‐risk features may be followed by periodical endoscopic ultrasonography. Although surgical approaches and operative methods are selected according to tumor size, location, growth pattern, and surgical teams, laparoscopic surgery has produced similar oncologic outcomes and is less invasiveness compared with open surgery. After resection, pathologic examination for diagnosis and risk assessment is mandatory, and genotyping is also recommended for high‐risk GISTs. Endoscopic resection techniques, although feasible, are not routinely indicated for most mini‐GISTs or micro‐GISTs. Cancer 2016;122:3110–8. © 2016 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.

Management Colorectal Gastrointestinal Stromal Tumors (Gists) in Surabaya

Introduction: Colorectal gastrointestinal stromal tumors (GISTs) mesenchymal tumor is very uncommon. GISTs effect mostly on the stomach and small intestine and rarely occur in the colon, rectum and esophagus, that originating from precursors of the interstitial cells that originate of Cajal. The symptoms of gastrointestinal stromal tumor depend on the site and size of the tumor, and may include abdominal pain, gastrointestinal bleeding or signs of obstruction; small tumors may, however, be asymptomatic. Some of the patients with gastrointestinal stromal tumor have bloody stools, obstruction and abdominal pain as the commonest manifestation. Immunocytochemical staining for CD117 is helpful in confirming the diagnosis. Case presentation: We report 3 new cases of GISTs: two occurred at the rectal and the other at descending Colon. Two cases are over 50 years of age and, and all cases the chief complain of bowel obstruction, abdominal pain in two cases, and one case with anemia and urine retention. All the patients were operated and were permormed pathology examinatiom. All case ware positive result for immunocytochemical staining CD117. All cases we had presented had size more than 5 cm are considered as unfavorable prognostic factors to Fletcher criteria, all patients scheduled for chemotherapy with Glivec but just one patient continued to used Glivec. Post surgery follows up one patient post milles with urinary incontinence complaints found and that patients are trained to CIC (intermittent catheterization). Conclusion: Colorectal gastrointestinal stromal tumors are very rare and can present as mass abdomen. Resection and chemotherapy are the treatment of choice.

Gastrointestinal stromal tumors of the colon and rectum

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. GISTs of the colon and rectum are rare, comprising 5% of all cases. There are few data available for colorectal GISTs to guide management. Although they can be small and found incidentally, the majority appear to be at high risk and carry a worse prognosis than gastric GISTs. Surgery remains the mainstay of treatment for primary disease. GISTs are targeted effectively with tyrosine kinase inhibitors (TKIs) such as imatinib mesylate. GISTs are best treated by a multidisciplinary team comprising the surgeon, medical oncologist, pathologist, and radiologist; this approach has the potential benefits of increasing the number of resectable cases through neoadjuvant treatment, optimizing the timing of surgery and organ preservation, reducing recurrence and surgical morbidity, and prolonging survival. On completion of this article, the reader should be able to summarize the diagnosis, specific characteristics, and management of gastrointestinal stromal tumors of the colon and rectum.

Surgery for gastrointestinal stromal tumors (GISTs) of the stomach and small bowel: short- and long-term outcomes over three decades.

Many studies on gastrointestinal stromal tumors (GISTs) derive from tertiary referral centers, but few examine strictly population-based cohorts. Thus, we evaluated the clinical features, surgical treatments, clinical outcomes, and factors predicting the survival of patients with GISTs in a population-based series. Patients with GISTs diagnosed at Stavanger University Hospital over three decades (1980-2012) were analyzed. Data were retrieved from hospital records. Descriptive statistics and survival analyses (Kaplan-Meier) are presented. A limited number of colorectal GISTs (n = 6) restricted most analyses to those with a gastric or small bowel location. Among 66 patients surgically treated for GISTs, 60 patients (91 %) had either a gastric or a small bowel localization. Females comprised 61 %. The median age at diagnosis was 63 (range, 15-88) years. Clinical symptoms were recorded in 43 patients (65 %). Complete tumor resection was achieved in 85 % of the patients. During follow-up, 6 patients were surgically treated for local recurrence or metastatic disease. The median follow-up time was 6.1 years. At last follow-up, 30 patients (46 %) were deceased, 10 of whom died from GISTs. The median overall survival was 10.4 years. For GISTs with a gastric or small bowel location, a 1- and 5-year disease-specific survival of 100 and 96 %, and a relapse-free survival of 96 and 78 % were observed. Male gender, incidental diagnosis, smaller tumor size, a low mitotic rate, an intact pseudocapsule, low-risk categorization, and an early stage were significantly associated with improved outcomes. Surgery in a low-volume, population-based setting yields enhanced long-term disease and recurrence-free survival for patients with GISTs of the stomach or small bowel. Incidental diagnosis, complete tumor resection, and low-risk categorization are good predictors of long-term prognosis.

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.

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.

Colorectal gastrointestinal stromal tumor

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm arising in the digestive tract, with an estimated prevalence of 15-20 per 1,000,000. GISTs are related to the interstitial cells of Cajal and are characterized by constitutive over-expression of the transmembrane tyrosine kinase receptor KIT. This is produced by a patognomonic mutation of the proto-oncogene c-kit that occurs in up to 90% of cases. Exon 11 is affected most frequently; exons 9 and 13 are less commonly involved. One-third of GISTs lacking KIT mutations exhibits alternative activating mutations in the PDGFRα gene. Colorectal GISTs represent about 5-10% of the cases, mainly located in the rectum that is the third common site. Benign GISTs are more common, but many tumors are of uncertain malignant potential; tumor size and rate of mitosis are still the most reliable criteria for assessing the risk of an aggressive behavior. Surgery is the first-line treatment for resectable non-metastatic colorectal GIST. Standard oncologic resection is inappropriate because skip metastases and lymphatic spread are rarely reported. Segmental colectomy with negative margins is recommended, and local excision is oncologically adequate in highly selected rectal tumors. Radical surgery alone is not always curative especially in high-risk GISTs, and half of patients develops local recurrences or distant metastases after R0 operation. Medical therapeutic strategies have rapidly evolved after the introduction of targeted molecular therapy. Efficacy and safety of imatinib mesylate was first demonstrated in patients with metastatic and unresectable disease. Adjuvant and neoadjuvant use of imatinib are promising therapeutic options to improve the outcome of surgery to downstage unresectable lesions and to allow less extensive resections.

Clinicopathologic Analysis of Gastrointestinal Stromal Tumors of the Colon and Rectum

Purpose: This study's aim is to investigate the clinicopathologic characteristics of colorectal gastrointestinal stromal tumors (GISTs) and to evaluate the result of those tumors. Methods: We retrospectively reviewed 22 patients who had been diagnosed with primary colorectal GISTs and who had undergone a surgical resection between October 1996 and July 2008. Results: Colorectal GISTs accounted for 0.28% of all colorectal malignancies and 7.7% of all GISTs. Rectal GISTs (19, 86.4%) were more common than colonic GISTs (3, 13.6%). According to the National Institute of Health's (NIH) grading system, there were 1 (4.5%) very low, 5 (22.7%) low, 4 (18.2%) intermediate, and 12 (54.6%) high-risk tumors. The disease recurred in 7 patients (1 with intermediate risk and 6 with high risk). Recurrence sites were the liver (42.9%), the peritoneum (71.5%), and the lymph nodes (14.3%). Adjuvant imatinib therapy and/or radiation therapy were done for patients with microscopically positive margins of resection and high risk, of which one experienced a recurrence at 95 months after surgery. The five-year recurrence rates were 0% in the very-low-grade and low-grade groups, 33.3% in the intermediate-grade group, and 37.5% in the high-grade group. The five-year overall survival rates were 100% in the very-low-grade and low-grade groups, 66.7% in the intermediate-grade group, and 62.5% in the high-grade group. Conclusion: Poor prognosis of colorectal GISTs was closely related to the tumor's histologic grade and size. Integrating surgery, molecular therapy, and radiation therapy might improve outcomes, but further study with more cases is needed.

Gastrointestinal Stromal Tumors of the Colon and Rectum

Purpose: This study was designed to review the clinical characteristics of gastrointestinal stromal tumors (GISTs) of the colon and rectum and to evaluate their immunohistochemical and pathologic features based on the current National Institutes of Health criteria. Methods: Patient and disease characteristics, pathologic features, surgical or endoscopic management, and clinical outcomes of 11 patients with GISTs diagnosed and primarily treated at our institution between March 1995 and February 2009 were evaluated. Results: Colorectal GISTs accounted for 4.4% of all GISTs. The primary location was the rectum (8 cases). Four patients had high-risk GISTs, 4 patients had low-risk GISTs, and 3 patients had very low-risk GISTs. All tumors were c-kit positive. Four patients underwent a radical resection, whereas 7 patients underwent an endoscopic resection (n=3) or a transanal excision (n=4). Two high-risk patients without adjuvant Imatinib mesylate therapy developed metastases, but the other highrisk patients with adjuvant Imatinib mesylate therapy didn't. Conclusion: Colorectal GISTs occurred predominantly in the rectum. Because GISTs do not metastasize through the lymphatics, small GISTs that are amenable to local excision or endoscopic resection can be treated by either of these techniques as long as negative microscopic margins are obtained around the primary tumor. Patients with high-risk GISTs should be considered for the use of Imatinib mesylate as adjuvant therapy.