Clinicopathologic study of 275 cases of gastrointestinal stromal tumors: the experience at 3 large medical centers in Mexico

Gastrointestinal Stromal Tumors: Alexandria University Experience

Introduction Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract (GIT) that can arise in any parts of the GIT. The clinical behavior and prognosis of GISTs remain unpredictable. The purpose of this study was to evaluate the clinicopathological features and prognostic factors of GISTs.

Methods The medical files of 93 patients with nonmetastatic GIST presented to our hospital were reviewed. The clinical and pathological parameters, treatment, and follow-up data were collected and correlated to survival outcome using univariate and multivariate analyses.

Results The median age of patients was 48.9 years with a slight male predominance. Abdominal pain (39.8%) was the commonly presenting symptom. About 60% of GISTs originated from the stomach and 22% from the small intestine. Tumors stained positive for CD117 in 95.7%. The median diameter of the tumors was 7 cm. Mitotic counts were < 5/50 high power field in 55.9% of tumors. About 44% of patients had high risk tumors. All patients underwent surgery and about 60.2% of patients received adjuvant imatinib mesylate.

The 5-year disease-free survival (DFS) and overall survival (OS) were 74.5 and 80%, respectively. Margin status, tumor site, tumor size, mitotic counts, and risk score were significantly associated with DFS and OS in both univariate and multivariate analyses.

Conclusion Surgery is the mainstay treatment for nonmetastatic GISTs. Tumor size, tumor location, margin status, mitotic count, and risk score were predictive factors for DFS and OS of GISTs.

Retrospective Analysis of Chilean and Mexican GI Stromal Tumor Registries: A Tale of Two Latin American Realities

PURPOSE

Like other malignancies, GI stromal tumors (GIST) are highly heterogeneous. This not only applies to histologic features and malignant potential, but also to geographic incidence rates. Several studies have reported GIST incidence and prevalence in Europe and North America. In contrast, GIST incidence rates in South America are largely unknown, and only a few studies have reported GIST prevalence in Latin America.

PATIENTS AND METHODS

Our study was part of a collaborative effort between Chile and Mexico, called Salud con Datos. We sought to determine GIST prevalence and patients' clinical characteristics, including survival rates, through retrospective analysis.

RESULTS

Overall, 624 patients were included in our study. Our results found significant differences between Mexican and Chilean registries, such as stage at diagnosis, primary tumor location, CD117-positive immunohistochemistry status, mitotic index, and tumor size. Overall survival (OS) times for Chilean and Mexican patients with GIST were 134 and 156 months, respectively. No statistically significant differences in OS were detected by sex, age, stage at diagnosis, or recurrence status in both cohorts. As expected, patients categorized as being at high risk of recurrence displayed a trend toward poorer progression-free survival in both registries.

CONCLUSION

To the best of our knowledge, this is the largest report from Latin America assessing the prevalence, clinical characteristics, postsurgery risk of recurrence, and outcomes of patients with GIST. Our data confirm surgery as the standard treatment of localized disease and confirm a poorer prognosis in patients with regional or distant disease. Finally, observed differences between registries could be a result of registration bias.

Efficacy and Safety of Endoscopic Treatment for Gastrointestinal Stromal Tumors in the Upper Gastrointestinal Tract

Background/Aims:

Endoscopic treatment (ET) has been applied for decades to treat subepithelial tumors, including gastrointestinal stromal tumors (GISTs). However, the efficacy of ET remains debatable. In this study, we evaluated the efficacy and safety of ET for GISTs in the upper gastrointestinal tract.

Methods:

This retrospective single-center study included 97 patients who underwent ET. All patients were enrolled from July 2014 to July 2018. Parameters such as demographics, size, resection margin, complications, pathological features, procedure time, total cost, and follow-up were investigated and analyzed.

Results:

Our study achieved 100% en bloc resection and 77.4% (72/93) R0 resection. The most common location was the fundus with a mean tumor size of 2.1±1.4 cm. The mean age, procedure time, hospital stay, and cost were 59.7±11.3 years, 64.7±35.2 minutes, 6.8 days, and 5,337 dollars, respectively. According to National Institutes of Health classification, 63 (64.9%), 26 (26.8%), 5 (5.2%), and 3 (3.1%) patients belonged to the very low, low, intermediate, and high risk classification, respectively. Immunohistochemistry results showed a 100% positive rate of CD34, DOG-1, CD117, and Ki67. A mean follow-up of 21.3±13.0 months showed no recurrence or metastasis.

Conclusions:

ET is effective and safe for curative removal of GISTs in the upper gastrointestinal tract, and it can be a treatment of choice for patients with no metastasis.

Melanotic Xp11-associated tumor of the sigmoid colon: A case report

BACKGROUND

Melanotic Xp11-associated tumors are rare mesenchymal-derived tumors. So far, most primary melanotic Xp11-associated tumors have been reported in the kidney, and reports of this tumor in the gastrointestinal tract are rare.

CASE SUMMARY

Here we describe the case of a 25-year-old woman who presented with a melanotic Xp11-associated tumor in the sigmoid colon. Colonoscopy revealed a large mucosal bulge in the sigmoid colon, approximately 32 cm inside the anus. The surface was rough with local erosion. The tumor was brittle on biopsy and bled easily. Computed tomography revealed thickening of the rectal wall with edema. Postoperative pathology indicated the likelihood of a perivascular epithelioid cell tumor. Histologically, the tumor comprised plump epithelioid cells with abundant clear to lightly eosinophilic cytoplasm and round nuclei arranged in an alveolar or trabecular pattern. The tumor cells were strongly positive for HMB-45, Melan-A, Cathepsin K, and TFE3 but negative for vimentin, smooth muscle actin, S100 protein, CD10, CK20, and desmin. The tumor cells had a low Ki-67 labeling index (approximately 2%). Fluorescence in situ hybridization revealed TFE3 fracture. Based on these histologic and immunohistochemical features, a diagnosis of melanotic Xp11-associated tumor of the sigmoid colon was made.

CONCLUSION

In summary, we report the clinicopathological features of a primary tumor that is extremely rare in the sigmoid colon and review the clinicopathological characteristics of melanotic Xp11-associated tumors, compatible with the very rare tumor termed “melanotic Xp11 translocation renal cancer” in all aspects.

Gastrointestinal stromal tumors: 16 years' experience within a university hospital

AIM

the aim was to convey our 16-year experience regarding gastrointestinal stromal tumors within in a high volume university hospital. Factors that may impact on patient survival were evaluated.

MATERIAL AND METHODS

all patients diagnosed with gastrointestinal stromal tumors in our clinic over a 16-year period were retrospectively evaluated. All patients included in the study had their tumors surgically resected. Survival analyses were performed using the Kaplan-Meier method. Survival time comparisons between groups were performed using the log-rank test. The effect of continuous variables on survival times were evaluated via a Cox-regression analysis with a backward conditional method.

RESULTS

one hundred and thirty-five patients (76 males and 59 females) were included into the study and the mean age was 62.8 ± 13.3 years. Overall survival time was 121.3 ± 7.0 months and the 5-year survival rate was 66.6 ± 4.2%. Patients with colorectal tumors had significantly lower survival times than patients with tumors located in the stomach (p = 0.001) and small intestine (p = 0.033). Patients with moderate risk scores had a significantly longer survival compared to patients with high risk scores (p = 0.003) and patients with tumor recurrence had a significantly shorter survival (p < 0.001). There was no significant relationship between survival and factors such as gender and tumor size (p > 0.05). However, age, Ki-67 and the mitotic index were poor prognostic factors and C-kit was considered as a good prognostic factor.

CONCLUSION

some of the findings in this study are consistent with published data. However, our data significantly differs from previous studies such as the common finding of the effect of gender and tumor size on survival.

Obscure Gastrointestinal Bleeding Due to a Small Intestinal Gastrointestinal Stromal Tumor in a Young Adult

The source of most cases of gastrointestinal bleeding is the upper gastrointestinal tract. Since bleeding from the small intestine is very rare and difficult to diagnose, time is required to identify the source. Among small intestine bleeds, vascular abnormalities account for 70-80%, followed by small intestine tumors that account for 5-10%. The reported peak age of the onset of small intestinal tumors is about 50 years. Furthermore, rare small bowel tumors account for only 1-2% of all gastrointestinal tumors. We describe a 29-year-old man who presented with obscure anemia due to gastrointestinal bleeding and underwent laparotomy. Surgical findings revealed a well-circumscribed lesion measuring 45 × 40 mm in the jejunum that initially appeared similar to diverticulosis with an abscess. However, the postoperative pathological diagnosis was a gastrointestinal stromal tumor with extramural growth.

Neoadjuvant imatinib: longer the better, need to modify risk stratification for adjuvant imatinib

BACKGROUND

Multimodality treatment of gastrointestinal stromal tumor (GIST) with surgery and adjuvant imatinib mesylate (IM), along with an emerging role for neoadjuvant IM prior to evaluation for resectability has resulted in high survival rates.

METHODS

We conducted a retrospective analysis of prospectively collected data of patients who underwent surgery for GIST, prior to or followed by IM therapy. A total of 112 patients underwent surgery between January 2009 and March 2015 at our centre. This included 27 patients with upfront resectable disease, 76 patients with locally advanced GIST who received neoadjuvant IM followed by surgery and 9 patients with metastatic disease who had excellent response to IM and were taken for surgery.

RESULTS

The primary tumor in the non metastatic patients was in the stomach (53%), duodenum (16%), rectum (12%), jejunum (11%), ileum (7%), and others (2%). Median duration of neoadjuvant IM was 5 months with 4 patients showing disease progression during neoadjuvant IM. Ninety-three percent of all patients had R0 resections, while 7% had R+ resections. The estimated 3- and 5-year DFS in non-metastatic patients was 86.1% and 67% respectively with a 3- and 5-year median OS of 95.4% and 91.7% respectively. Five-year PFS and OS for the metastatic patients was 88.8% and 100% respectively. Lack of adjuvant IM was the only factor related to inferior PFS and OS.

CONCLUSIONS

Longer duration of neoadjuvant IM should be considered in locally advanced GIST prior to surgery and resection may be considered in responding metastatic patients.

Gastrointestinal stromal tumor: 15-years' experience in a single center

Background

Gastrointestinal stromal tumor (GIST) is known for its wide variability in biological behaviors and it is difficult to predict its malignant potential. The aim of this study is to explore the characteristics and prognostic factors of GIST.

Methods

Clinical and pathological data of 497 GIST patients in our center between 1997 and 2012 were reviewed.

Results

Patients were categorized into very low-, low-, intermediate- and high-risk groups according to modified National Institutes of Health (NIH) consensus classification system. Among the 401 patients untreated with imatinib mesylate (IM), 5-year overall survival (OS) in very low-, low-, intermediate- and high-risk groups was 100%, 100%, 89.6% and 65.9%; and 5-year relapse-free survival (RFS) was 100%, 98.1%, 90.9% and 44.5%, respectively. Univariate analysis revealed that sex, tumor size, mitotic rate, risk grade, CD34 expression, and adjacent involvement were predictors of OS or RFS. COX hazard proportional model (Forward LR) showed that large tumor size, high mitotic rate, and high risk grade were independent risk factors to OS, whereas high mitotic rate, high risk grade and adjacent organ involvement were independent risk factors to RFS. The intermediate-high risk patients who received IM adjuvant therapy (n = 87) had better 5-year OS and RFS than those who did not (n = 188) (94.9% vs. 72.1; 82.3% vs. 56.3%, respectively). Similarly, advanced GIST patients underwent IM therapy (n = 45) had better 3-year OS and 1-year progression-free survival (PFS) than those who didn’t (n = 42) (75.6% vs. 6.8%; 87.6% vs. 12.4%, respectively).

Conclusions

Very low- and low-risk GISTs can be treated with surgery alone. Large tumor size, high mitotic rate, high risk grade, and adjacent organ involvement contribute to the poor outcome. IM therapy significantly improves the survival of intermediate-high risk or advanced GIST patients.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2482-14-93) contains supplementary material, which is available to authorized users.

The clinical pathological features, diagnosis, treatment and prognosis of small intestine primary malignant tumors

The aim of the study was to describe and analyze the clinicopathological features and diagnosis of Chinese patients with small intestine primary malignant tumors and to explore the best therapy to small bowel adenocarcinoma (SBA). More than 26,000 patients with digestive tract malignant tumors received treatment in PLA hospital from 2000 to 2011, and among them, there were 887 patients who had small intestine primary malignant tumors, and 666 of 887 patients had the completed basic clinical documents. We retrospectively analyzed the correlation between clinical and pathological features of the 666 patients and analyzed the survival and prognosis of 173 SBA patients with follow-up data. Both the number of patients with primary malignant tumors of the small intestine and the number of patients who received chemotherapy showed an increasing trend. The ratio of male to female was 1.58:1. The male patients significantly exceed the female patients with tumors of non-ampullary duodenum, jejunum and duodenal ampulla; and most of the patients are over 60 years of age. For patients burdened with either of the pathological types of tumors, the males exceeded the females, but there was no significant difference. Abdominal pain was the main clinical manifestation for patients with tumors of non-ampullary duodenum, jejunum and ileum, and the most common clinical manifestations were jaundice and abdominal pain for patients with ampullary duodenal tumors, adenocarcinoma, neuroendocrine tumors and sarcoma. In addition, patients with stromal tumors were prone to gastrointestinal bleeding. Gastrointestinal endoscopy was the most common examinational procedure. Patients under 60 years of age were prone to surgery and chemotherapy after surgery, and patients over 60 years of age were prone to supportive treatment and chemotherapy without surgery. The medium overall survival of patients who received surgery without chemotherapy, chemotherapy after surgery, chemotherapy without surgery and supportive treatment were 40.0, 35.0, 9.0 and 7.5 months, respectively. For the 173 SBA patients with follow-up data, treatment, age and distant metastasis were important prognostic factors; 149 of 173 SBA patients received only surgery, and the depth of tumor invasion, lymph node metastasis and surgical approach were important prognostic factors. Adjuvant chemotherapy had not provided significant benefit to prolong OS in patients with adenocarcinoma. The incidence of small intestine primary malignant tumors is very low, and it is difficult to diagnose. The patients should be aggressively treated and regularly followed up with related clinical and pathological features. Currently, surgery is the most effective treatment, and the role of chemotherapy needs further large-scale clinical studies.

Endoscopic submucosal dissection of large gastrointestinal stromal tumors in the esophagus and stomach

BACKGROUND AND AIM

Gastrointestinal stromal tumors (GISTs), the most common mesenchymal tumors of the digestive tract with potential for malignant transformation, are mainly treated by open surgery or laparoscopic resection. The aim of this retrospective study was to evaluate the clinical efficacy, safety, and feasibility of endoscopic submucosal dissection (ESD) for large-size (2-5 cm) GISTs in the esophagus and stomach.

METHODS

A total of 31 patients with large-size GISTs in the esophagus (6 patients) and stomach (25 patients) underwent ESD between September 2008 and December 2011. Demographics, clinical data, therapeutic outcomes, complications, pathological characteristics, risk classification, and follow-up outcomes were recorded.

RESULTS

ESD was successfully performed in 31 patients at age of 59.06 ± 7.23 years (range: 46-74). The mean time of the procedure was 70.16 ± 16.25 min (range: 40-105). Perforation for 2-10 mm occurred in six patients (19.35%) and was endoscopically repaired with clips or nylon bands, with no conversions to open surgery. Intraoperative bleeding occurred in three patients (9.68%) and was corrected with argon plasma coagulation or hot biopsy forceps. No mortalities occurred. The mean size of the resected tumors was 2.70 ± 0.72 cm (range: 2.0-5.0). Out of the 31 patients, 24 (77.42%) were at very low risk and 7 (22.58%) were at low risk. Positive rate of CD117, DOG-1, and CD34 were 83.87%, 12.90%, and 100%, respectively. A follow up for 14.29 ± 8.99 months (range: 3-39) showed no recurrence or metastasis.

CONCLUSIONS

ESD appears to be an effective, safe, and feasible treatment for large-size GISTs in the esophagus and stomach.

Gastrointestinal stromal tumor of the ampulla of Vater with osteoclastic giant cells, osteoid-like matrix deposition, and aneurysmal bone cyst-like features

Gastrointestinal stromal tumors are a heterogeneous group with a wide spectrum of histologic features. We describe the first case of 61-year-old woman who presented gastrointestinal stromal tumors of the ampulla of Vater with osteoclast-like giant cells surrounding osteoid-like material and aneurismal bone cyst-like areas. The phenotype was supported by light microscopy and corroborated by immunohistochemistry analysis. Because of the presence of osteoid-like and aneurismal bone cyst-like components, it is first necessary to make differential diagnosis with other entities such as metastatic osteosarcoma. Our case shows another form of differentiation that has not previously been reported.

Endoscopic ultrasonography-guided diagnosis of subepithelial tumors

Subepithelial lesions are frequently discovered during routine endoscopic examinations. These lesions represent a wide spectrum of heterogeneous benign to malignant conditions. Most of these lesions are asymptomatic. There is no consensus regarding how to manage these lesions. Over the last 2 decades, the approach to these lesions has significantly improved owing to the introduction of endoscopic ultrasonography, fine-needle aspiration, immunohistochemical staining methods, and different treatment options. This article discusses the nature of subepithelial lesions, focusing on the most recent developments that use endoscopic ultrasonography to diagnose and manage these lesions.

Evaluation of prognostic factors and their capacity to predict biological behavior in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are c-KIT-signaling-driven mesenchymal tumors of the human digestive tract, many of which have c-KIT or PDGFRα activating mutations. The authors studied the immunohistochemical markers, c-KIT and PDGFRα mutations, in GISTs and their association with the clinicopathological and clinical follow-up in 145 GISTs. Tumors were located mainly in the stomach, the median tumor size being 7.5 cm. The mitotic index was ≤5 mitoses per 50 high-power fields in 61% of cases, 96% expressed CD117, and c-KIT or PDGFRα mutations were detected in 68% of cases. The median follow-up of the series was 52 months (range = 1 to 244.9 months). Tumor size, cell morphology, mitotic index, incomplete resection, Fletcher's risk classification, Ki-67 overexpression, and c-KIT mutations were associated with progression-free survival. Incomplete resection and mitotic activity also provide information about overall survival. In conclusion, complete clinicopathological, immunohistochemical, and genetic descriptions are necessary to characterize this disease and optimize its clinical management.

Perivascular epithelioid cell tumor of the sigmoid colon with transcription factor E3 expression

We describe here a 62-year-old woman who presented with a perivascular epithelioid cell tumor arising in the sigmoid colon. Computed tomography revealed a 5-cm-sized intraluminal fungating mass. Histologically, the tumor consisted of plump, epithelioid cells with abundant clear-to-lightly eosinophilic cytoplasm and round nuclei, arranged in an alveolar or trabecular pattern. The tumor cells were strongly positive for HMB-45 and TFE3, but negative for vimentin, cytokeratin, smooth muscle actin, S100 protein, CD117, CD34, synaptophysin, chromogranin, CD10, hepatocyte antigen, CD1a, and desmin. The tumor cells had a high Ki-67 labeling index (up to 20%). Fluorescent in situ hybridization showed no evidence of the EWS rearrangement. Based on these histologic and immunohistochemical features, our patient was diagnosed with a perivascular epithelioid cell tumor of the sigmoid colon.

Imatinib mesylate for the treatment of gastrointestinal stromal tumor

Gastrointestinal stromal tumors (GISTs) are rare neoplasms of mesenchymal origin arising in the GI tract. These tumors are characterized by activating mutations of either receptor tyrosine kinase KIT or PDGFRA, which are found in 85% of cases. The introduction of imatinib mesylate (IM), which targets the kinases presenting with these molecular alterations, has dramatically changed the management of these rare tumors, which were resistant to conventional cytotoxic chemotherapy, both in advanced and localized phases. IM is orally available, has a favorable safety profile and induces partial responses and disease stabilization in up to 80% of patients with advanced GIST. Recently, IM was approved for the postoperative treatment of patients with completely resected localized GIST.

Gastrointestinal stromal tumors: a clinicopathological and immunohistochemical study of 121 cases

BACKGROUND

Primary mesenchymal tumors of the gastrointestinal tract are a heterogeneous group of tumors with a wide clinical spectrum, of which gastrointestinal stromal tumors (GIST) typically occur in middle-aged to older individuals. This study evaluated the clinicopathological and morphological features of GIST of the intestinal tract.

METHODS

The study included 108 gastrointestinal and 13 extra-gastrointestinal stromal tumors involving the mesentry and retroperitoneum between January 1989 and July 2007. Immunohistochemical expression of CD117, CD34, SMA, Desmin, S100, and Ki-67 were studied.

RESULTS

GIST comprised 108 of 120 (90%) of the mesenchymal tumors. The tumor was located in the stomach in the majority (55%) of patients followed by small intestine (30%), retroperitoneum (7%) and the colorectum (4%). There was a significant correlation between tumor size and mitotic index, with larger tumors having higher mitotic index (p < 0.001). Mitotic index per 5 mm(2) correlated with high cellularity (p < 0.001), presence of necrosis (p < 0.001) and presence of mucosal invasion (p = 0.01). Expression of CD117 was seen in 94%, CD34 in 59%, SMA in 41%, S-100 in 33%, and desmin in 4% of tumors.

CONCLUSION

We found GIST to be the most common mesenchymal tumor of the gastrointestinal tract.

Surgically treated primary malignant tumor of small bowel: A clinical analysis

AIM: To evaluate the clinical presentation, treatment and survival of patients with primary malignant tumor of small bowel (PMTSB).

METHODS: Clinicopathologic data about 141 surgically treated PMTSB patients (91 males and 50 females) at the median age of 53.5 years (range 23-79 years) were retrospectively analyzed.

RESULTS: The most common initial clinical features of the patients were intermittent abdominal discomfort or vague abdominal pain (67.4%), abdominal mass (31.2%), bowel obstruction (24.1%), hemotochezia (21.3%), jaundice (16.3%), fever (14.2%), coexistence of bowel perforation and peritonitis (5.7%), coexistence of gastrointestinal bleeding and shock (5.0%), and intraabdominal bleeding (1.4%). Ileum was the most common site of tumor (44.7%), followed by jejunum (30.5%) and duodenum (24.8%). PMTSB had a nonspecific clinical presentation. Segmental bowel resection (n = 81) was the most common surgical procedure, followed by right hemi-colectomy (n = 15), pancreaticoduodenectomy (n = 10), and others (n = 19). Twenty-seven adenocarcinoma patients and 13 malignant lymphoma patients received adjuvant chemotherapy with 5-fluorouracil and cyclophosphamide, adriamycin, vincristine and prednisone, respectively. Information about 120 patients was obtained during the follow-up. The median survival time of PMTSB patients was 20.3 mo. The 1-, 3- and 5-year survival rate was 75.0% (90/120), 40.0% (48/120) and 20.8% (25/120), respectively. Adenocarcinoma was found in 73.7% (42/57), 21.1% (12/57) and 15.8% (9/57) of the patients, respectively. Gastrointestinal stromal tumor was observed in 80.0% (20/25), 72.0% (18/25) and 36.0% (9/25) of the patients, respectively. Carcinoid was detected in 100.0% (15/15), 80.0% (12/15) and 46.7% (7/15) of the patients, respectively. Malignant lymphoma was demonstrated in 69.2% (9/13), 30.8% (4/13) and 0% (0/13) of the patients, respectively.

CONCLUSION: En bloc resection is the principal therapy for most PMTSB and chemotherapy is the important treatment modality for malignant lymphoma and other malignant tumors of small bowel which cannot be radically removed.

Smooth-to-striated muscle transition in human esophagus: an immunohistochemical study using fetal and adult materials

BACKGROUND

A craniocaudal transition from smooth to striated muscle occurs in the fetal mouse esophagus muscularis propria, until finally the entire muscle component becomes striated. Although no such investigation has been conducted using human fetuses, the transition appears to be incomplete.

METHODS

In horizontal sections of 10 human fetuses between 9 and 16 weeks of gestation, we identified immunoreactivity for smooth muscle actin (SMA), striated muscle myosin heavy chain (MyH), desmin, PGP9.5, S100 protein, c-kit, and CD68 in the thoracic esophagus. The TUNEL method was used to identify apoptosis. For comparison, the same immunohistochemistry was conducted using 10 adult esophaguses.

RESULTS

In fetuses at all stages examined, a transition zone was found in the upper thoracic esophagus that was attached to the middle one-third of the trachea. In the transition zone, the MyH-positive longitudinal muscle fibers were surrounded by flat, SMA-positive cells, whereas the MyH-positive circular fibers were sometimes located adjacent to the SMA-positive fibers. However, in adults, smooth muscle tended to be clearly separated from striated muscle. The distribution of cells showing immunoreactivity for PGP9.5, S100 or c-kit did not differ between the oral and anal sides of the transition zone. Desmin was positive in the muscularis propria, but negative in the muscularis mucosae. Neither CD68-positive macrophages nor TUNEL-positive cells were present in the esophagus.

CONCLUSIONS

In the human esophagus, the smooth-to-striated muscle transition appears to stop at the mid-thoracic level. Cell death or transdifferentiation of smooth muscle appears unlikely, but phenotypic transformation into desmin-positive myofibroblasts is a possibility.

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

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

A pharmaco-economic analysis of second-line treatment with imatinib or sunitinib in patients with advanced gastrointestinal stromal tumours

Second-line treatments recommended by the National Cancer Center Network to manage advanced-stage gastrointestinal stromal tumours (GIST) were evaluated to determine the cost and cost-effectiveness of each intervention in the Mexican insurance system, the Instituto Mexicano del Seguro Social (IMSS). Treatments examined over a 5-year temporal horizon to estimate long-term costs included 800 mg day⁻¹ of imatinib mesylate, 50 mg day⁻¹ of sunitinib malate (administered in a 4 week on/2 week rest schedule), and palliative care. The mean cost (MC), cost-effectiveness, and benefit of each intervention were compared to determine the best GIST treatment from the institutional perspective of the IMSS. As sunitinib was not reimbursed at the time of the study, a Markov model and sensitivity analysis were conducted to predict the MC and likelihood of reimbursement. Patients taking 800 mg day⁻¹ of imatinib had the highest MC (±s.d.) of treatment at $35 225.61 USD (±1253.65 USD); while sunitinib incurred a median MC of $17 805.87 USD (±694.83 USD); and palliative care had the least MC over treatment duration as the cost was $2071.86 USD (±472.88 USD). In comparison to palliative care, sunitinib is cost-effective for 38.9% of patients; however, sunitinib delivered the greatest survival benefit as 5.64 progression-free months (PFM) and 1.4 life-years gained (LYG) were obtained in the economic model. Conversely, patients on imatinib and palliative care saw a lower PFM of 5.28 months and 2.58 months and also fewer LYG (only 1.31 and 1.08 years, respectively). Therefore, economic modeling predicts that reimbursing sunitinib over high dose imatinib in the second-line GIST indication would deliver cost savings to the IMSS and greater survival benefits to patients.

Imatinib mesilate for the treatment of gastrointestinal stromal tumour

BACKGROUND

The molecular hallmark of gastrointestinal stromal tumours (GISTs), the mutation of the KIT gene, was discovered 10 years ago. GISTs have since been recognized as separate pathological entities among sarcomas, and have become a model for targeted treatment of solid tumours. Imatinib mesilate, which was approved in 2002 for the treatment of patients with advanced GIST, has dramatically changed the course of the disease.

OBJECTIVE

This article will focus on the development of imatinib mesilate in the treatment of patients with GIST.

METHODS

A Pubmed search was performed using the keywords 'imatinib', 'gastrointestinal stromal', 'GIST', 'KIT' and 'PDGFR'. Websites of the American Society of Clinical Oncology and the European Society of Medical Oncology were searched for data reported in abstract form at recent symposiums. Personal communications from opinion leaders were sought for additional information that might be relevant.

RESULTS

Imatinib has changed the clinical course of patients with advanced GISTs and further development in the adjuvant setting as well as prospective assessment of predictive factors are the current focus of ongoing research.