New developments in gastrointestinal stromal tumor

Cost-Effectiveness Analysis of Tyrosine Kinase Inhibitors in Gastrointestinal Stromal Tumor: A Systematic Review

Background: The introduction of tyrosine kinase inhibitor (TKI) therapy has dramatically improved the clinical effectiveness of patients with locally advanced and/or metastatic gastrointestinal stromal tumors (GIST), and this systematic review was conducted aiming at the cost-effectiveness analysis of TKIs in GIST.

Methods: A thorough literature search of online databases was performed, using appropriate terms such as “gastrointestinal stromal tumor or GIST,” “cost-effectiveness,” and “economic evaluation.” Data extraction was conducted independently by two authors, and completeness of reporting and quality of the evaluation were assessed. The systematic review was conducted following the PRISMA statement.

Results: Published between 2005 and 2020, 15 articles were incorporated into the systematic review. For advanced GIST, imatinib followed by sunitinib was considered cost-effective, and regorafenib was cost-effective compared with imatinib re-challenge therapy in the third-line treatment. For resectable GIST, 3-year adjuvant imatinib therapy represented a cost-effective treatment option. The precision medicine-assisted imatinib treatment was cost-effective compared with empirical treatment.

Conclusion: Although identified studies varied in predicted costs and quality-adjusted life years, there was general agreement in study conclusions. More cost-effectiveness analysis should be conducted regarding more TKIs that have been approved for the treatment of GIST.

Systematic Review Registration:https://www.crd.york.ac.uk/, PROSPERO: CRD42021225253.

Pancreatic Metastasis from Gastrointestinal Stromal Tumor of the Stomach: A Case Report

We report the first documented case of pancreatic metastasis from a gastrointestinal stromal tumor of the stomach. A 42-year-old Japanese man presented with severe abdominal discomfort. Computed tomography of the abdomen showed a huge heterogeneous mass consisting of cystic and solid components in the left upper abdomen. (18)F-Fluorodeoxyglucose positron-emission tomography revealed high tracer uptake in the abdominal mass. After total gastrectomy with lymphnodectomy was performed, a hard mass was palpated in the pancreatic tail. The pancreatic tumor was also resected under the therapeutic strategy. Histological examinations of the resected gastric and pancreatic specimens revealed that both tumors consisted of uniform spindle cells with a fascicular growth pattern and were immunohistochemically positive for CD34 and CD117/KIT. Gene sequencing analysis of DNA from each tumor revealed an identical deletion of 21 nucleotides in exon 11 of the gene KIT. On the basis of these results, we concluded that the pancreatic tumor was a metastatic tumor from the gastrointestinal stromal tumor of the stomach.

Short- and Long-Term Outcomes of Laparoscopic Versus Open Resection for Gastric Gastrointestinal Stromal Tumors: A Propensity Score-Matching Analysis

Published reports on laparoscopic resection of gastric gastrointestinal stromal tumor (GIST) were limited to small experiences and selection bias. Two hundred fourteen patients who underwent primary gastric GIST resection at our institution (January 2006-December 2012) were identified from a prospectively collected database. Laparoscopic resections (LAP) were performed in 133 patients, and open resections (OPEN) were performed in 81 patients. The short- and long-term outcomes were analyzed using propensity-score matching (PSM) by comparing the clinicopathological factors between these groups. The tumor resection method and tumor size were significantly different between the LAP and OPEN groups. After PSM, there were no differences (P > 0.05) in these clinicopathological factors. The LAP group had less blood loss and shorter operation time, time to first flatus, time to first fluid diet, time to gastric tube removal, and postoperative stay before PSM. In addition, there were no differences regarding the time of drainage tube removal or hospitalization expense. Other than the time of gastric tube removal, which was similar in these 2 groups, the short-term outcomes were similar before and after PSM. The rates of postoperative complications in the LAP and OPEN groups were 6.8% and 22.8%, respectively, before PSM (P = 0.001) and 5.6% and 22.5%, respectively, after PSM (P = 0.004). The multivariate analyses for complications showed that tumors were located in the middle of the stomach, and the operation method and proximal gastrectomy were independent risk factors before and after PSM. The 5-year cumulative survival rates in the LAP and OPEN groups were 95.4% and 85.9%, respectively, (P = 0.07) before PSM and 93.1% and 91.9%, respectively, (P = 0.69) after PSM (not significantly different). Laparoscopic resection for gastric GISTs had better short-term outcomes and similar long-term outcomes compared with open surgery. Localized gastric GISTs can be treated with laparoscopic surgery.

Gastrointestinal Stromal Tumor Mimicking as Ovarian Tumor in Gynaecologic Oncology

To report the clinical presentation and outcomes of a series of patients who presented with abdominal/pelvic mass or pelvic pain and were diagnosed with a gastrointestinal stromal tumor (GIST). Retrospective data were collected of all patients who presented with an abdominal/pelvic mass or pelvic pain between January 2010 and July 2015 and who were ultimately diagnosed with a GIST. The patients' medical records were reviewed. A literature review was also conducted. The event free survival and overall survival was calculated for all patients using Kaplan Meier curve (SPSS19-SPSS Inc. USA). A total ten patients were identified with GIST during the study period. Eight of ten patients had a tumor in the small intestine, one in sigmoid colon and one in base of small bowel mesentry. The mean tumor size was 13.9 cm (range, 3.9 to 24 cm). A complete resection was achieved in all 10 patients. No patient had distance metastasis. There were no intraoperative complications. One patient developed postoperative intestinal fistula and was managed conservatively. All patients were treated with imatinib after surgery. The mean follow-up time was 18 months (range, 2 to 47 months). The seven of the 10 patients (70 %) with no evidence of disease, two (20 %) lost follow up and one patient developed recurrence during follow up period and was started on sunitinib and patient died during follow up period because of disease. Gastrointestinal stromal tumors should be considered in the differential diagnosis of patients presenting with an abdominal/pelvic mass or pelvic pain in Gynaecologic oncology department. In such unusual circumstances the complete resection and appropriate adjuvant treatment results in complete durable remission.

Carcinoma of the recto-vaginal septum. Comprehensive literature review

Carcinoma of the recto-vaginal septum is an extremely rare entity. We performed a MEDLINE-based search on recto-vaginal septum carcinoma, focussing on its management, in order to clarify which are the best treatment options for this disease. In addition an unpublished case report has been added to the review. 34 case reports were included in our review. Surgery and adjuvant chemoradiation therapy seem to be the most common treatment option. However, since primary surgical treatment leads to mutilation by removing a large portion of the vagina and the anal sphincter with a permanent terminal colostomy, primary platinum-based chemoradiation therapy could be considered. In case of extragastrointestinal stromal tumours primary surgical treatment seems to be the best option. Due to the rarity of this entity only limited data is available. Therefore further investigation is necessary.

Gastrointestinal stromal tumor solitary distant recurrence in the left brachialis muscle

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the gastrointestinal tract that are most commonly found in the stomach. Although GISTs can spread to the liver and peritoneum, metastasis to the skeletal muscle is very rare and only four cases have previously been reported. These cases involved concurrent skeletal metastases of primary GISTs or liver metastases. Here, we report the first case of a distant recurrence in the brachialis muscle after complete remission of an extra-luminal gastric GIST following a wedge resection of the stomach, omental excision, and adjuvant imatinib therapy for one year. Ten months after therapy completion, the patient presented with swelling and tenderness in the left arm. Magnetic resonance imaging revealed a large mass in the brachialis muscle, which showed positivity for c-kit and CD34 upon pathologic examination. This is the first reported case of a solitary distant recurrence of a GIST in the muscle after complete remission had been achieved.

Incidence and survival analysis of gastrointestinal stromal tumors in shanghai: a population-based study from 2001 to 2010

Objectives. A population-based study was undertaken to investigate the epidemiological features of gastrointestinal stromal tumors (GISTs) in Shanghai, especially the incidence and the preliminary exploration of survival. Methods. A total of 1923 patients with GISTs diagnosed from 2001 to 2010 in Shanghai were reviewed. The annual incidence and overall survival of GISTs were calculated; Cox proportional hazards' regression was used to analyze several prognostic factors. Results. The average crude incidence of GISTs was 2.11 per 100,000 between 2004 and 2008, and the age-standardized incidence was 1.28 per 100,000. The incidence increased gradually from 2004 to 2008. In addition, 57% of cases had GIST in the stomach and 33% in the intestine. The 5-year overall survival of GISTs was 86.98%. The Cox regression analysis showed older age (≥65 yr versus <40 yr, HR = 5.085; (40, 65) yr versus <40 yr, HR = 1.975), male gender (HR = 1.474), and tumor locations (intestinal versus stomach, HR = 1.609) were predictors of its mortality. Conclusion. GISTs, mainly occurring in the stomach, are more common in elderly population, with an increasing incidence from 2004 to 2008. Older age, male gender, and tumor locations are risk factors for its mortality.

Extragastrointestinal stromal tumor in the rectovaginal septum in an adolescent

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We report a rare case of EGIST in rectovaginal septrum.

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Adolescent patient who died due to an aggressive EGIST

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Infrequent type of pelvic EGIST and literature review

Establishment and characterization of novel cell lines and xenografts from patients with gastrointestinal stromal tumors

At present, no suitable GIST model exists for the analysis of drug resistance or metastasis using established human gastrointestinal stromal tumor (GIST) cell lines or xenografts even though the molecular mechanisms of drug resistance, progression and metastasis require clarification. The aim of this study was to establish and characterize human GIST cell lines and xenografts that can be used for evaluating drug resistance or various new molecularly targeted therapies. GIST tissues from patients were cultured and implanted under the skin of NOG (NOD/Shi-scid, IL-2Rrnu) mice. Two new cell lines (GK1C and GK3C) and three xenografts (GK1X, GK2X and GK3X) were generated from these clinical samples. The established GIST cell lines and xenografts were investigated for tumorigenesis and imatinib sensitivity. These cell lines and xenografts showed characteristic GIST morphology and exhibited KIT expression profiles similar to those of the patient samples. In addition, these GIST cell lines and xenografts were sensitive to imatinib. In conclusion, new human GIST cell lines and xenografts were established and maintained through repeated passages. These models will enable further study of combination therapies and the mechanisms of resistance, and allow testing of novel targeted monotherapies and combination therapies.

Long-term efficacy of imatinib for treatment of metastatic GIST

PURPOSE

Imatinib is an effective and approved treatment for advanced gastrointestinal stromal tumor (GIST). Continuous imatinib treatment is recommended by current guidelines. This review summarizes the long-term efficacy and safety of imatinib for patients with metastatic GIST.

METHODS

Key clinical studies were reviewed-including B2222, S0033, and BFR14-with particular emphasis on recently reported results of the long-term clinical outcome of imatinib for metastatic GIST.

RESULTS

The B2222 and S0033 studies recently reported 10-year follow-up results that demonstrate the long-term efficacy of imatinib. Furthermore, results from the BFR14 study demonstrate that imatinib treatment should not be interrupted and that the efficacy of imatinib following reintroduction is inferior compared with the continuous administration group. The S0033 study also supports the importance of dose optimization and dose escalation of imatinib in patients with KIT exon 9 mutations or progressive disease. These studies demonstrate that individual patient characteristics should be evaluated for optimal patient management. Managing adverse events proactively is very important to maintain compliance.

CONCLUSIONS

The results from these studies demonstrate that long-term imatinib extends survival in patients with advanced GIST. Furthermore, these studies support the safety of long-term imatinib therapy in this patient population.

Clinical practice guideline for accurate diagnosis and effective treatment of gastrointestinal stromal tumor in Korea

Despite their rarity in incidence and prevalence, gastrointestinal stromal tumors (GISTs) have emerged as a distinct and noteworthy pathogenetic entity. The clinical management of GISTs has rapidly evolved due to the recent elucidation of their oncogenic signal transduction pathway and the introduction of molecular-targeted therapies. Successful management of GISTs requires a multidisciplinary approach firmly based on an accurate histopathologic diagnosis. In 2007, the Korean GIST study group published the first guideline for optimal diagnosis and treatment of GISTs in Korea. The second version of the guideline was published in 2010. Herein, we provide the results of relevant clinical studies for the purpose of further revision to the guideline. We expect this new guideline will enhance the accuracy of diagnosis, as performed by members of the Korean associate of physicians involved in GIST patient care, thus improving the efficacy of treatment.

Gastrointestinal stromal tumors as an incidental finding in patients with a presumptive diagnosis of ovarian cancer

Objective

To report the clinical presentation and oncologic outcomes of a series of patients who presented with an abdominal or pelvic mass and were diagnosed with a gastrointestinal stromal tumor (GIST).

Methods

Data were obtained on all patients who presented with an abdominal or pelvic mass between September 2007 and June 2010 and who were ultimately diagnosed with a GIST. The patients' medical records were reviewed. A literature review was also conducted.

Results

Six patients were identified who met the inclusion criteria. All six patients had a tumor in the intestinal tract arising from the small bowel. The mean tumor size was 12 cm (range, 6 to 22 cm). A complete resection was achieved in five of the six patients. There were no intraoperative complications; one patient had a postoperative complication. Two patients were treated with imatinib after surgery. The mean follow-up time was 32 months (range, 0.3 to 40 months). At the last follow-up, five of the six patients were without any evidence of disease. One patient died of an unrelated hepatic encephalopathy. The incidence in our institution is 3%.

Conclusion

GISTs are uncommon; however, they should be considered in the differential diagnosis of patients presenting with an abdominal or pelvic mass.

Clinical practice guideline for accurate diagnosis and effective treatment of gastrointestinal stromal tumor in Korea

Despite the rarity in incidence and prevalence, gastrointestinal stromal tumor (GIST) has emerged as a distinct pathogenetic entity. And the clinical management of GIST has been evolving very rapidly due to the recent recognition of its oncogenic signal transduction pathway and the introduction of new molecular-targeted therapy. Successful management of GIST requires a multidisciplinary approach firmly based on accurate histopathologic diagnosis. However, there was no standardized guideline for the management of Korean GIST patients. In 2007, the Korean GIST study group (KGSG) published the first guideline for optimal diagnosis and treatment of GIST in Korea. As the second version of the guideline, we herein have updated recent clinical recommendations and reflected changes in diagnosis, surgical and medical treatments for more optimal clinical practice for GIST in Korea. We hope the guideline can be of help in enhancing the quality of diagnosis by members of the Korean associate of physicians involving in GIST patients's care and subsequently in achieving optimal efficacy of treatment.

Survival of patients with multiple primary malignancies: a study of 783 patients with gastrointestinal stromal tumor

BACKGROUND

We sought to investigate the characteristics and survival rate of patients with gastrointestinal stromal tumor (GIST) associated with other primary malignancies.

PATIENTS AND METHODS

A total of 783 patients with GIST were identified from 1995 to 2007. Additional primaries included tumors not considered metastasis, invasion, or recurrence of GIST, nor non-melanoma skin cancer. Data on gender, age at diagnosis, follow-up time after diagnosis, and death were collected.

RESULTS

Of the 783 patients with GIST, 153(20%) were identified with at least one additional primary. Patients with additional primaries were more often men (M : F 1.5 versus 1.3) and older (66 versus 53 years). More patients had another cancer diagnosed before (134) than after (52) GIST. Primaries observed before GIST were cancers of the prostate (25), breast (12), esophagus (9), and kidney (7) and melanoma (6). Lung (5) and kidney (5) primaries were the most frequent after GIST. The 5-year survival was 68% for patients with primaries before GIST, 61% for patients with primaries after GIST, 58% for patients with GIST only, and 49% for patients with two or more primaries in addition to GIST (P = 0.002).

CONCLUSIONS

Approximately 20% of patients with GIST develop other cancers. Inferior median 5-year survival was observed in patients with GIST with two or more other cancers. The etiology and clinical implications of other malignancies in patients with GIST should be investigated.

Advances in imaging diagnosis of extra-gastrointestinal stromal tumors

Since Mazur and Clark first proposed the term gastrointestinal stromal tumors (GIST) in 1983, GIST have become a hot topic of pathological and clinical research. Stromal tumors that occur outside the gastrointestinal tract (EGIST) are relatively rare. Imaging technology plays an important role in the diagnosis of EGIST. In this article, we will review the advances in imaging diagnosis of EGIST.

Gastrointestinal stromal tumors: report of an audit and review of the literature

Gastrointestinal stromal tumors (GISTs), tumors characterized by c-KIT mutations, are the most frequent mesenchymal tumors of the digestive tract. The stomach is the most commonly involved site. Localization, size and mitotic rate are reliable predictors of survival and the two milestones of GISTs treatment are surgery and imatinib. This article is aimed to report the data of an audit, carried out on the morphological and clinical aspects of the disease and to review the present knowledge on GISTs. A total of 172 patients with GISTs (M : F=1 : 1; mean age 65 years) were recruited. The stomach was the most frequently involved site. In 50% of the cases the tumor was smaller than 5 cm, whereas major symptoms were observed in 43% of the cases. Predictors of progressive disease were present only in a small percentage of cases but the disease was in the metastatic phase in over 25% of the cases at diagnosis. Familial aggregation was rare but a consistent share of the patients (21%) had other synchronous or metachronous cancers. The most frequent mutations were in-frame deletions and point mutations of c-KIT exon 11. This report confirms in part the available data on GIST in a consecutive series of patients recruited in Italy and shows that only large collaborative multicenter studies provide data sound enough to enable making reasonable clinical and therapeutic choices, and suggests that, as a measure of secondary prevention, a diagnostic definition should be obtained in all submucosal lesions of the GI tract and that GIST patients should be screened for second tumors.

Gastrointestinal stromal tumor: role of interventional radiology in diagnosis and treatment

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasm of the gastrointestinal tract. The interventional radiologist plays an important role in the diagnosis and locoregional therapy for metastatic GISTs. Radiofrequency ablation (RFA) is a potentially curative option for patients exhibiting partial response to imatinib with focal residual disease. RFA can also be used for local control of focal hepatic or peritoneal metastasis. Hepatic embolization or chemoembolization is reserved for the treatment of progressive liver disease in imatinib-resistant patients who are not suitable for sunitinib as a second-line therapy.

Gastrointestinal stromal tumors: key to diagnosis and choice of therapy

The common feature of gastrointestinal stromal tumors (GISTs) is the expression of KIT protein or acquisition of activating, constitutive mutations in the KIT or platelet-derived growth factor receptor alpha (PDGFRA) genes that are the early oncogenic events during GIST development. With these discoveries, GIST has emerged as a distinct sarcoma entity, enabling the introduction of targeted therapy using the inhibition of KIT/PDGFRA and their downstream signaling cascade. The introduction of a small-molecule tyrosine kinase inhibitor, imatinib mesylate, to clinical practice has revolutionized the treatment of patients with advanced GISTs and is currently approved as first-line treatment for patients with metastatic and/or inoperable GISTs. Mutation screening is currently a tool in GIST diagnosis, assessment of sensitivity to tyrosine kinase inhibitors, and prediction of achieving response to molecularly targeted therapy. This article discusses the histologic and molecular criteria for distinguishing GISTs from other types of sarcoma, and the molecular diagnostic tools that are currently available or in development to assist in therapy decisions.

Upregulation of discoidin domain receptor 2 in nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) is associated with Epstein-Barr virus (EBV) and has high metastatic potential. Discoidin domain receptors (DDR1, DDR2) are receptor-type tyrosine kinases activated by collagen. Their ability to induce expression of matrix metalloproteinase is related with tumor invasion. Therefore, we aim to investigate DDRs gene expression and its regulation in NPC.

METHODS AND RESULTS

By use of real-time quantitative polymerase chain reaction (Q-PCR), DDR2 gene expression but not DDR1 was significantly higher in primary and metastatic NPC. DDR2 was predominantly distributed in NPC tumor cells rather than in infiltrating lymphocytes. EBV Z-transactivator (Zta) transfection may distinctly elevate DDR2 level. Furthermore, data from reporter assay indicate that Zta could transactivate DDR2 promoter activity, suggesting the possible upregulation mechanism.

CONCLUSION

DDR2 was differentially upregulated in NPC and modulated by EBV Zta protein. DDR2 may play a role in NPC invasion and serve as a diagnostic and therapeutic target.

The challenge of conducting pharmacoeconomic evaluations in oncology using crossover trials: the example of sunitinib for gastrointestinal stromal tumour

This paper examines the challenge of conducting economic evaluations to support patient access to cancer therapies when the cost-effectiveness estimation is hampered by crossover trial design. To demonstrate these limitations, we present the submission to the Canadian Drug Review (CDR) of a cost-effectiveness evaluation of sunitinib versus best supportive care (BSC) for the treatment of gastrointestinal stromal tumour in patients intolerant or resistant to imatinib. The economic model generated an incremental cost-effectiveness ratio for sunitinib versus BSC of dollars 79,884/quality-adjusted life-year gained. Eight months after initial submission, CDR granted a final recommendation to fund sunitinib following the manufacturer's appeal against their first recommendation. Although cost-effectiveness is an important consideration in reimbursement decisions, there is a need for improved decision-making processes for cancer drugs, as well as a better understanding of the limitations of clinical trial design.

Perivascular epithelioid cell tumor of the liver coexisting with a gastrointestinal stromal tumor

Approximately 10% of patients with gastrointestinal stromal tumors (GIST) develop other neoplasms, either synchronously or metachronously. In this report we describe coexistence of a gastrointestinal stromal tumor and a hepatic perivascular epithelioid cell tumor (PEComa) in a 51-year-old woman with no evidence of tuberous sclerosis. A subcapsular hepatic nodule (0.8 cm in diameter) was found during surgery for symptomatic gastric neoplasm (15 cm in diameter) arising from the lesser curvature. Both tumors revealed histomorphological and immunohistochemical features confirming a diagnosis of a small incidental hepatic PEComa and a high risky extramural gastric GIST, respectively. The patient remained disease-free 25 mo after surgery with no evidence of tumor recurrence or new neoplasms. To our knowledge, this is the first report of PEComa in a patient with GIST. Hepatic lesions detected synchronously or metachronously in patients with GISTs may represent histogenetically distinct lesions and should be sampled to confirm or exclude metastatic GISTs.

Sunitinib in the management of gastrointestinal stromal tumours (GISTs)

AIMS

Gastrointestinal stromal tumours (GISTs) are rare mesenchymal neoplasms of the gut with a 5-year survival of approximately 50%. Surgery remains the treatment of choice in resectable disease, with conventional chemotherapy largely ineffective. Over 90% of GIST possesses mutations in the c-KIT oncogene, producing an overactive tyrosine kinase, which may be driving the malignant process. Imatinib inhibits the aberrant tyrosine kinase and imatinib therapy in metastatic disease has shown significant clinical benefit. However, resistance typically develops within 2 years, with the need for further therapy. This article aims to introduce the reader to a new development in cancer therapeutics.

METHODS

A literature search was performed using the MEDLINE database to identify publications relevant to the review. References within these articles were used to expand the search. Abstracts from recent ASCO symposia were hand searched for relevant articles.

FINDINGS

Sunitinib (SU11248) is a novel multi-targeted tyrosine kinase inhibitor with activity not only against the receptor tyrosine kinase product of c-KIT but also other cell-signalling pathways that may be relevant in GIST; FLT3, platelet-derived growth receptor (PDGFR) and vascular endothelial growth factor receptor (VEGFR). Two Phase II trials and one Phase III trial have investigated the activity of sunitinib against imatinib-resistant GIST. Early results showed significant benefits in time to disease progression that led to licensing of the drug in America and more recently in Europe. A Phase III trial comparing dose-increased imatinib and sunitinib in progressed GIST is currently planned.

CONCLUSIONS

Initial clinical results with sunitinib are promising and suggest a future role. Further studies are needed before sunitinib can be recommended for the routine treatment of imatinib-refractory GIST.

Sarcoma

Sarcomas comprise a heterogeneous group of mesenchymal neoplasms. They can be grouped into 2 general categories, soft tissue sarcoma and primary bone sarcoma, which have different staging and treatment approaches. This review includes a discussion of both soft tissue sarcomas (malignant fibrous histiocytoma, liposarcoma, leiomyosarcoma, synovial sarcoma, dermatofibrosarcoma protuberans, angiosarcoma, Kaposi sarcoma, gastrointestinal stromal tumor, aggressive fibromatosis or desmoid tumor, rhabdomyosarcoma, and primary alveolar soft-part sarcoma) and primary bone sarcomas (osteosarcoma, Ewing sarcoma, giant cell tumor, and chondrosarcoma). The 3 most important prognostic variables are grade, size, and location of the primary tumor. The approach to a patient with a sarcoma begins with a biopsy that obtains adequate tissue for diagnosis without interfering with subsequent optimal definitive surgery. Subsequent treatment depends on the specific type of sarcoma. Because sarcomas are relatively uncommon yet comprise a wide variety of different entities, evaluation by oncology teams who have expertise in the field is recommended. Treatment and follow-up guidelines have been published by the National Comprehensive Cancer Network (www.nccn.org).

Gastrointestinal stromal tumour

Gastrointestinal stromal tumours are the most common mesenchymal neoplasm of the gastrointestinal tract and are highly resistant to conventional chemotherapy and radiotherapy. Such tumours usually have activating mutations in either KIT (75-80%) or PDGFRA (5-10%), two closely related receptor tyrosine kinases. These mutations lead to ligand-independent activation and signal transduction mediated by constitutively activated KIT or PDGFRA. Targeting these activated proteins with imatinib mesylate, a small-molecule kinase inhibitor, has proven useful in the treatment of recurrent or metastatic gastrointestinal stromal tumours and is now being tested as an adjuvant or neoadjuvant. However, resistance to imatinib is a growing problem and other targeted therapeutics such as sunitinib are available. The important interplay between the molecular genetics of gastrontestinal stromal tumour and responses to targeted therapeutics serves as a model for the study of targeted therapies in other solid tumours.

Risk Criteria and Prognostic Factors for Predicting Recurrences After Resection of Primary Gastrointestinal Stromal Tumor

BACKGROUND

The introduction of adjuvant imatinib in gastrointestinal stromal tumors (GISTs) raised debate over the accuracy of National Institutes of Health risk criteria and the significance of other prognostic factors in GIST.

METHODS

Tumor aggressiveness and other clinicopathological factors influencing disease-free survival (DFS) were assessed in 335 patients with primary resectable CD117-immunopositive GISTs (median follow-up, 31 months after primary tumor resection) from a prospectively collected tumor registry.

RESULTS

Overall median DFS was 37 months, and estimated 5-year DFS was 37.8 %. In univariate analysis, high or intermediate risk group (P < .000001), mitotic index >5/50 high-power field (P < .00001), primary tumor size >5 cm (P < .00001), nongastric primary location (P = .0001), male sex (P = .01), R1 resection/tumor rupture (P = .0003), and epithelioid cell or mixed cell pathological subtype (P = .05) negatively affected DFS. In multivariate analysis, statistically significant factors negatively influencing DFS for model 1 were mitotic index >5/50 high-power field (P = .004), primary tumor size >5 cm (P = .001), male sex (P = .003), R1 resection/tumor rupture (P = .04), and nongastric primary tumor location (P = .02), and for model 2 were high/intermediate risk primary tumor (P < .0001 and P = .008, respectively), male sex (P = .007), resection R1/tumor rupture (P = .01), and nongastric primary tumor location (P = .02). Five-year DFS for high, intermediate, and low/very low risk group was 20%, 54%, and 96%, respectively.

CONCLUSIONS

The risk criteria for assessing the natural course of primary GISTs were validated, but additional independent prognostic factors-primary tumor location and sex--were also identified.

Predictive factors for long-term effects of imatinib therapy in patients with inoperable/metastatic CD117(+) gastrointestinal stromal tumors (GISTs)

THE PURPOSE

To analyze the outcomes of treatment and factors predicting effects of imatinib (IM) therapy in inoperable/metastatic gastrointestinal stromal tumors (GIST) CD117(+) patients.

MATERIALS AND METHODS

We identified 232 patients in a prospectively collected Clinical GIST Registry with advanced inoperable/metastatic GIST treated with IM 400-800 mg daily (129 males and 103 females and median age 56 years). Median follow-up time was 26 months.

RESULTS

The estimated 3-year progression-free survival (PFS; calculated from the date of the start of IM) was 54% and median PFS was 40.5 months. The following factors significantly and negatively influenced PFS in univariate analysis: poor baseline World Health Organization (WHO) performance status > or = 2 (P < 0.00001), tumor genotype indicating other than KIT exon 11 isoform (P = 0.005), baseline high neutrophils count (P < 0.00001), age <45 years at the diagnosis (P = 0.04), mitotic index >10/50 high-power fields (HPF) (P = 0.001), GIST histological type other than spindle-cell (P = 0.03), baseline low albumin level (P = 0.0005), low baseline hemoglobin level (P < 0.00001), and primary overtly malignant tumors (unresectable and/or metastatic lesions at presentation) (P = 0.05). We identified four factors negatively affecting PFS, statistically significant (P < 0.05) in multivariate analysis: baseline poor WHO performance status > or = 2, high baseline neutrophils count (>5 x 10(9)/l), tumor genotype indicating the presence of non-exon 11 KIT mutant and mitotic index >10/50 HPF.

CONCLUSIONS

We confirmed that many advanced GIST patients benefit from IM therapy for a prolonged time, although resistance to therapy is observed. We identified four independent biological factors influencing the PFS during long-term IM therapy.