Surgical treatment of gastrointestinal stromal tumour of the rectum in the era of imatinib

English version of Japanese Clinical Practice Guidelines 2022 for gastrointestinal stromal tumor (GIST) issued by the Japan Society of Clinical Oncology

The Japan Society of Clinical Oncology Clinical Practice Guidelines 2022 for gastrointestinal stromal tumor (GIST) have been published in accordance with the Minds Manual for Guideline Development 2014 and 2017. A specialized team independent of the working group for the revision performed a systematic review. Since GIST is a rare type of tumor, clinical evidence is not sufficient to answer several clinical and background questions. Thus, in these guidelines, we considered that consensus among the experts who manage GIST, the balance between benefits and harms, patients' wishes, medical economic perspective, etc. are important considerations in addition to the evidence. Although guidelines for the treatment of GIST have also been published by the National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO), there are some differences between the treatments proposed in those guidelines and the treatments in the present guidelines because of the differences in health insurance systems among countries.

Adjuvant therapy for rare rectal gastrointestinal stromal tumors: A case report

Key Clinical Message

Anorectal gastrointestinal stromal tumors are extremely rare, constituting less than 0.1% of rectal tumors. Surgical resection using a transanal wide excision followed by adjuvant therapy with tyrosine kinase inhibitors can be a successful treatment combination to remove the mass and prevent recurrence while preserving the integrity of the anal sphincter.

Abstract

Gastrointestinal stromal tumors (GISTs) are a rare subset of neoplasms, accounting for about 1%-2% of primary gastrointestinal malignancies. The stomach is the most common site for GISTs, with anorectal GISTs being exceptionally rare, representing only 0.1% of all rectal tumors. The standard approach for managing localized GIST involves complete surgical excision to achieve negative microscopic margins (R0) while preserving the tumor capsule and maintaining anal sphincter function. Surgical resection with transanal wide excision followed by adjuvant therapy using tyrosine kinase inhibitors can successfully remove the mass, prevent recurrence, and preserve the anal sphincter's integrity. Adjuvant therapy with imatinib is the recommended treatment for all localized GISTs assessed to have an intermediate or high risk of relapse. Here, we report a case of a 63-year-old male with a rectal GIST who underwent transanal wide excision followed by adjuvant therapy with tyrosine kinase inhibitors.

Trans-anal Minimally Invasive Surgery Combined With a Robotic Anterior Approach for Sleeve Resection of a Huge Rectal Gastrointestinal Stromal Tumor

Due to anatomical complexity, large rectal gastrointestinal stromal tumors (GISTs) in the pelvis at the anterior aspect often require extended abdominal surgery to obtain clear surgical margins. Here, we show our trans-anal minimally invasive surgery combined with a robotic anterior approach for a huge low rectal GIST that was widely in contact with the prostate and urethra. By performing lateral dissection first, we can identify the orientation of critical organs such as the prostate, urethra, and neurovascular bundles, facilitating anterior anorectal dissection without urethral injury. Although the combination with a transabdominal robotic approach was required because of firm inflammatory adhesion between the tumor and prostate, the preceding trans-anal dissection plane facilitated the robotic anterior dissection and contributed to achieving complete dissection with negative resection margins.

KIT and PDGFRA Variants and the Survival of Patients with Gastrointestinal Stromal Tumor Treated with Adjuvant Imatinib

Adjuvant imatinib improves the recurrence-free survival and overall survival (OS) of patients with gastrointestinal stromal tumors (GISTs) who have a high risk of recurrence after surgery and is now considered standard treatment. Yet, OS benefit has been demonstrated in only one randomized study, the Scandinavian Sarcoma Group XVIII/AIO trial, where patients with high-risk GISTs were allocated to either 1 year or 3 years of adjuvant imatinib. SSGXVIII/AIO is also the only randomized trial in which adjuvant imatinib duration exceeding 2 years was evaluated. In this trial, the 3-year treatment led to a 45% reduction in the risk of death during the first 10 years that followed random allocation even though some of the patients did not have GISTs at tumor histology review, had mutations now known to be imatinib-resistant or had non-localized disease at study entry. In the subgroup of patients who had KIT exon 11 deletion/indel mutation, the reduction in the risk of death was 66% in favor of the longer treatment. Proper patient selection is of crucial importance since many patients are cured with surgery. Little evidence for OS benefit is available from randomized trials for patients whose GIST harbors KIT exon 9 mutation, KIT insertion mutation, PDGFRA D842V mutation, or lacks KIT and PDGFRA mutations. Adjuvant imatinib improves OS substantially if high-risk GISTs can be identified, treatment duration is long enough, and GISTs harbor an imatinib-sensitive mutation.

Rectal Gastrointestinal Stromal Tumors

Rectal gastrointestinal stromal tumors (GISTs) are rare types of tumors, but the incidence is increasing, and we now know more about the pathogenesis and management of rectal GIST. The main goal is to resect the tumor with negative microscopic margins. With the development of neoadjuvant Imatinib therapy, preoperative reduction in tumor size has become possible, thus introducing the chance for anus-preserving surgery, with better quality of life. We present a case of a 55-year-old female who presented to the emergency department with complaints of bleeding per rectum, abdominal pain, and pain on defecation. A 6-cm mass was detected during the rectal examination and a biopsy confirmed the diagnosis of GIST. The patient was given neoadjuvant imatinib chemotherapy for four months followed by trans-anal resection of the mass. The procedure was done successfully, and she received further adjuvant imatinib for a course of three years. Follow-up by magnetic resonance imaging and a colonoscopy after two years showed no recurrence. The patient is living healthily and doing well.

Surgical and Oncological Outcomes after Neoadjuvant Therapy for Non-Metastatic Gastric GISTs

Surgical resection with negative margins of non-metastatic gastric GISTs is considered the main therapeutic option in GISTs treatment. Neoadjuvant therapy with imatinib is associated with higher response rates in advanced GISTs. We reported 34 patients with non-metastatic gastric GISTs who underwent partial gastrectomy at the Oncology Center, Mansoura University, Egypt, after receiving a daily dose of 400 mg of imatinib as a neoadjuvant treatment in the period between October 2012 and January 2021. Twenty-two cases underwent open partial gastrectomy, and twelve cases had a laparoscopic partial gastrectomy. The median tumor size at diagnosis was 13.5 cm (range 9-26 cm) and the duration of neoadjuvant therapy was 10.91 months (range 4-12 months). Thirty-three patients had a partial response, while one patient showed progression of the disease on neoadjuvant treatment. Adjuvant therapy was conducted in 29 (85.3%) cases. Complications of neoadjuvant treatment were reported in seven cases in the form of gastritis, bleeding per rectum, fatigue, thrombocytopenia, neutropenia, and edema lower limbs. The disease-free survival (DFS) in this study was 34.53 months, and the overall survival (OS) was 37 months. Recurrence developed in two cases, gastric and peritoneal recurrence (25 and 48 months from the initial diagnosis, respectively). We have concluded that neoadjuvant treatment with imatinib for non-metastatic gastric GISTs is a safe and effective method for tumor downsizing and devitalization to allow minimally invasive and/or organ sparing surgery. Moreover, it decreases the risk of intraoperative tumor rupture and relapse, thus improving the oncological outcome of such tumors.

Gastrointestinal Stromal Tumours (GIST) of the Rectum: A Systematic Review and Meta-Analysis

Background: Rectal gastrointestinal stromal tumours (GISTs) have many treatment options, but uncertainty remains regarding the best treatment regimen for this rare pathology. The aim of this review is to assess the optimal management approach including timing of chemotherapy. Methods: PubMed, EMBASE, and Cochrane databases were searched for relevant articles comparing the impact of radical vs. local excision, and neoadjuvant vs. adjuvant therapy had on outcomes in the management of rectal GISTs. We specifically evaluated the influence that the aforementioned factors had on margins, recurrence, overall survival, 5-year disease-free survival, and hospital length of stay. Results: Twenty-eight studies met our predefined criteria and were included in our study, twelve of which were included in the quantitative synthesis. When comparing neoadjuvant versus adjuvant chemotherapy, our meta-analysis noted no significance in terms of margin negativity (R0) (odds ratio [OR] 2.01, 95% confidence interval [CI], 0.7−5.79, p = 0.20) or recurrence rates (OR 0.22, 95% CI, 0.02−1.91, p = 0.17). However, there was a difference in overall 5-year survival in favour of neoadjuvant therapy (OR 3.19, 95% CI, 1.37−7.40, * p = 0.007). Comparing local excision versus radical excision, our meta-analysis observed no significance in terms of overall 5-year survival (OR1.31, 95% CI, 0.81−2.12, p = 0.26), recurrence (OR 0.67, 95% CI, 0.40−1.13, p = 0.12), or 5-year disease-free survival (OR 1.10, 95% CI, 0.55−2.19, p = 0.80). There was a difference in length of hospital stay with a reduced mean length of stay in local excision group (mean difference [MD] 6.74 days less in the LE group; 95% CI, −6.92−−6.56, * p =< 0.00001) as well as a difference in R0 rates in favour of radical resection (OR 0.68, 95% CI, 0.47−0.99, * p = 0.05). Conclusion: Neoadjuvant chemotherapy is associated with improved overall 5-year survival, while local excision is associated with reduced mean length of hospital stay. Further large-volume, prospective studies are required to further define the optimal treatment regimen in this complex pathology.

Trans-anal surgery with the taTME technique for rectal gastrointestinal stromal tumors: a retrospective study

PURPOSE

Rectal gastrointestinal stromal tumors (GISTs) surgery is often challenging owing to the anatomical constraints of the narrow pelvis and tumor hugeness. Despite the increasing number of patients undergoing trans-anal total mesorectal excision (taTME) globally, the feasibility of trans-anal surgery with the taTME technique for rectal GISTs remains unclear. We aimed to evaluate the feasibility of trans-anal surgery with the taTME technique for rectal GISTs.

METHODS

Using a prospectively collected database, we retrospectively analyzed the clinical findings, surgical outcomes, pathological outcomes, urinary and anal functions, and prognoses of patients who underwent trans-anal surgery with the taTME technique for primary rectal GISTs at the National Cancer Center Hospital East from September 2014 to March 2020.

RESULTS

Twenty-one patients with primary rectal GISTs were included in this study. The median distance from the anal verge to the lower edge of the tumor was 40 mm (range, 15-60 mm), and the median tumor size was 59 mm (range, 11-175 mm). Moreover, seven and 14 patients underwent one-team and two-team surgeries, respectively, with curative intent. Nineteen patients (90.5%) underwent anus-preserving surgery, and the urinary tracts were preserved in all cases. Two-team surgery showed a significantly lower blood loss volume and shorter operation time than one-team surgery (58 vs. 222 mL, P = 0.017; 184 vs 356 min, P = 0.041, respectively). The pathological negative-margin resection rate was 100%. During the follow-up period, no patient developed local GIST recurrence and one (4.8%) developed distant metastasis.

CONCLUSION

Trans-anal surgery with the taTME technique is feasible for rectal GISTs, and two-team surgery may be more advantageous than one-team surgery in terms of operation time and blood loss.

Comparison of prognosis between neoadjuvant imatinib and upfront surgery for GIST: A systematic review and meta-analysis

Background: Significant survival benefit of adjuvant imatinib therapy has been observed in gastrointestinal stromal tumor (GIST). However, the impact of neoadjuvant imatinib on prognosis of GIST remains unclear. This meta-analysis aimed to compare the prognostic impact between upfront surgery and neoadjuvant imatinib plus surgery on GIST.

Methods: A comprehensive literature search was performed to identify eligible studies up to 30 Sep 2021, through PubMed, Embase, Web of Science, and Cochrane Library. Studies compared the impact of upfront surgery and neoadjuvant imatinib plus surgery on disease-free (DFS) or overall survival (OS) in patients with GIST were selected.

Results: Seven eligible studies with 17,171 patients were included. The reduction rates of tumor size in rectal and mixed site GIST were 33% and 29.8%, respectively. Neoadjuvant imatinib was not significantly associated with DFS compared with no-neoadjuvant therapy in rectal GIST (HR: 0.71, 95% CI: 0.35–1.41). The OS of rectal GIST was significantly improved by neoadjuvant imatinib compared with no-neoadjuvant therapy (HR: 0.36, 95% CI: 0.17–0.75).

Conclusion: Neoadjuvant imatinib therapy contributed to tumor shrinkage and R0 resection of rectal GIST. Neoadjuvant imatinib plus surgery significantly improved overall survival of rectal GIST in comparison with upfront surgery.

Neoadjuvant tyrosine kinase inhibitor therapy for patients with gastrointestinal stromal tumor: A propensity-matched analysis

BACKGROUND

Tyrosine kinase inhibitor (TKI) neoadjuvant therapy (NAT) is often given in gastrointestinal stromal tumors (GISTs) with the goal to facilitate less morbid resections and improve oncologic outcomes; however, the use of NAT for GIST is poorly studied.

METHODS

We reviewed patients with resected nonmetastatic GIST from 2003 to 2019. Overall (OS) and recurrence-free survival (RFS) were assessed with Kaplan-Meier modeling. We performed 1:1 propensity-matching for relevant clinicopathologic variables for receipt of NAT.

RESULTS

We identified 254 patients. Propensity 1:1 matching resulted in 33 patients per group. The median follow-up was 77 months with no difference in 10-year OS (68% vs. 73%), 5-year RFS (13% vs. 10%), or median RFS (24 vs. 27 months) for patients treated with NAT versus upfront resection (all P > 0.9). Hospital length-of-stay (both median 7 days) and Clavien-Dindo ≥ III complications (12% vs. 3%) were not different between groups (both P ≥ 0.35).

DISCUSSION

TKI NAT can be used to facilitate resection in select patients with surgically higher-risk GIST, however it does not result in an independent oncologic benefit.

The role of neoadjuvant imatinib in gastrointestinal stromal tumor (GIST) patients - 20 years of experience from a tertial referral center

Surgery is the cornerstone of gastrointestinal stromal tumor (GIST) treatment, and adjuvant therapy with imatinib has improved survival for high‐risk tumors. The use of imatinib preoperatively has been increasing, but efficacy and impact on patient outcomes have not been formally investigated. This is a retrospective study from a single‐center cohort of patients diagnosed with GIST and treated with neoadjuvant imatinib at Karolinska University Hospital in Stockholm, Sweden over a 20‐year period. Eighty‐four patients diagnosed with GIST and treated with neoadjuvant imatinib were identified and included. Tumors were located throughout the whole gastrointestinal tract but most frequently in the stomach (n = 29; 35%) and the small intestine (n = 30; 36%), followed by the rectum (n = 12; 14%) and the gastroesophageal junction (n = 10; 12%). The tumors were large (mean 10.5 cm) and decreased after treatment (mean 7.6 cm). Main indications for neoadjuvant imatinib were tumor size or anatomical location. None of the patients with stomach tumors and four patients with tumors near the gastroesophageal junction underwent gastrectomy. Three patients with tumors in the small intestine underwent pancreaticoduodenectomy, whereas seven patients with rectal tumors underwent rectal amputation. After surgery, 94% (n = 79) of the tumors had R0‐resection. About one‐fourth experienced local relapse or distant metastasis. In conclusion, neoadjuvant imatinib can reduce tumor size and prevent high morbidity due to more extensive surgery, or at least reduce the extent of the surgery, especially for tumors in the stomach or small intestine.

Recent Advancements in the Treatment of Rectal Gastrointestinal Stromal Tumor: In Era of Imatinib

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumor of the gastrointestinal tract, with an annual incidence of 10–15 cases per million. However, rectal GIST has a low incidence, accounting for approximately 0.1% of all rectal tumors. The treatment of rectal GISTs is still controversial and the relative unified guidelines and consensus opinions are inadequate. Treatment is based primarily on the clinical experience of the physician. The widespread application of neoadjuvant imatinib therapy allows diversification of treatment, especially in the choice of surgical methods. Herein, we reviewed the most recent literature and summarized the new progress in rectal tumor treatment, with the aim of providing patients with more systematic and individualized therapeutic strategies.

Prognostic Factors and Management of Colorectal Gastrointestinal Stromal Tumors

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.

Survival outcome of local vs. radical excision in rectal gastrointestinal stromal tumor: a SEER database analysis

Background

The choice of surgical strategy for patients with rectal gastrointestinal stromal tumor (GIST) remains controversial. This study aims to address whether the surgical procedure [local excision (LE) vs. radical excision (RE)] influences the survival outcomes.

Methods

The information of the patients recruited in this study was obtained from the Surveillance, Epidemiology, and End Results (SEER) database. A survival curve was used to evaluate the differences in cancer-specific survival (CSS).

Results

No significant difference was detected in the CSS between the LE and RE groups. Also, no significant differences were observed in the CSS between the two groups with respect to different T classification, N classification, tumor differentiation, tumor size, regional LN surgery, age, gender, race, chemotherapy, and radiotherapy. The T classification and age were independent prognostic factors in rectal GIST patients.

Conclusions

LE and RE have similar survival time after surgery, and LE could be considered as an effective surgical approach for rectal GIST.

OUP accepted manuscript

Background

Method

Results

Conclusion

Clinicopathological features, clinical efficacy on 101 cases of rectal gastrointestinal stromal tumors, and the significance of neoadjuvant therapy

Objective

To investigate the clinicopathological features and clinical efficacy among 101 cases of rectal gastrointestinal stromal tumors (GISTs) and to investigate the significance of imatinib mesylate (IM) neoadjuvant therapy.

Methods

The clinicopathological features, treatment methods, perioperative data, and prognosis of the patients were summarized and analysed in 101 patients with rectal GISTs who received treatment in the Gastrointestinal Surgery of West China Hospital of Sichuan University and the Affiliated Hospital of Guizhou Medical University from August 2002 to November 2020 in China.

Results

A total of 101 patients, including 64 males and 37 females, were aged from 22 to 79 years (55.4 ± 12.2 years). Among the 70 patients who underwent direct surgery, 8 were very low risk cases, 10 were low risk cases, 7 were intermediate risk cases, and 45 were high risk cases. Cox regression analysis showed that postoperative IM adjuvant treatment improved the disease-free survival (DFS) and overall survival (OS) of 52 intermediate and high risk patients. Among the 31 patients who received neoadjuvant therapy, the objective response rate (ORR) was 83.9% (26/31), and the disease control rate (DCR) reached 96.8% (30/31). Subgroup analysis was also conducted based on the tumour diameter. (1) Among the 36 patients with a diameter ≤ 5 cm, two patients received IM neoadjuvant therapy, while 34 patients received direct surgery. Neither univariate nor Cox regression analysis found that neoadjuvant therapy affected DFS and OS. (2) Among the 65 patients with a diameter > 5 cm, 29 received IM neoadjuvant therapy, and 36 received direct surgery. Patients who underwent neoadjuvant therapy had less blood loss (P = 0.022), shorter postoperative hospital stay (P = 0.001), increased anal retention rate (93.1% vs. 72.2%, P = 0.031), and decreased enterostomy rate (10.3% vs. 33.3%, P = 0.037) than those who underwent direct surgery. Cox regression analysis suggested that neoadjuvant therapy and postoperative IM adjuvant therapy improved DFS.

Conclusion

Rectal GISTs are relatively rare and highly malignant tumors. Postoperative oral IM therapy can improve the DFS and OS of intermediate and high risk patients. In patients with rectal GISTs with diameters > 5 cm, IM neoadjuvant therapy can improve anal retention rate, preserve the structure and function of the organs, reduce enterostomy rate, and improve prognosis.

Comparison of outcomes between neoadjuvant imatinib and upfront surgery in patients with localized rectal GIST: An inverse probability of treatment weighting analysis

BACKGROUND AND OBJECTIVES

This study aimed to compare outcomes between neoadjuvant imatinib and upfront surgery in patients with localized rectal gastrointestinal stromal tumors (GIST) patients.

METHODS

Eighty-five patients with localized rectal GIST were divided into two groups: upfront surgery ± adjuvant imatinib (Group A, n = 33) and the neoadjuvant imatinib + surgery + adjuvant imatinib (Group B, n = 52). Baseline characteristics between groups were controlled for with inverse probability of treatment weighting (IPTW) adjusted analysis.

RESULTS

The response rate to neoadjuvant imatinib was 65.9%. After the IPTW-adjusted analysis, patients who underwent neoadjuvant therapy had better distant recurrence-free survival (DRFS) and disease-specific survival (DSS) compared with those who underwent upfront surgery (5-year DRFS 97.8 vs. 71.9%, hazard ratio [HR], 0.15; 95% CI, 0.03-0.87; p = 0.03; 5-year DSS 100 vs. 77.1%; HR, 0.11; 95% CI, 0.01-0.92; p = 0.04). While no significant association was found between overall survival (OS) and treatment groups (p = 0.07), 5-year OS was higher for the neoadjuvant group than upfront surgery group (97.8% vs. 71.9%; HR, 0.2; 95% CI, 0.03-1.15).

CONCLUSIONS

In patients with localized rectal GIST, neoadjuvant imatinib not only shrunk the tumor size but also decreased the risk of metastasis and tumor-related deaths when compared to upfront surgery and adjuvant imatinib alone.

Transvaginal Resection of a Rectal Gastrointestinal Stromal Tumor: A Case Report

Gastrointestinal stromal tumors (GISTs) are a type of mesenchymal tumors. They are rare in rectum. This location is a surgical challenge due to the high morbidity after aggressive surgeries. We present the case of an 81-year-old female with a high-grade GIST treated with transvaginal excision and adjunctive therapy with imatinib. The postoperative period was uneventful without anal dysfunction. Within the types of surgical treatment available, transvaginal excision is an acceptable procedure in lesions located in the rectovaginal region.

The effect of neoadjuvant imatinib therapy on outcome and survival in rectal gastrointestinal stromal tumors: A multiinstitutional study

BACKGROUND AND OBJECTIVES

This study aimed to characterize the efficacy of neoadjuvant imatinib in rectal gastrointestinal stromal tumors (GISTs) and the prognostic characteristics of patients after surgery.

METHODS

Patients with rectal GISTs who received neoadjuvant imatinib between 2000 and 2019 were selected from 11 large-scale tertiary hospitals in China. The best response to neoadjuvant imatinib was assessed. Propensity score matching (PSM) was conducted to reduce confounders. Recurrence free survival (RFS) and overall survival (OS) were estimated using Kaplan-Meier method.

RESULTS

Of the 100 patients, 75, 18, and 7 had a partial response (PR), stable disease (SD), and progressive disease (PD), respectively. The median tumor size decreased from 5 cm before treatment to 4 cm after treatment (p < 0.001). A total of 31 patients underwent genetic testing after surgery; 23 of patients with exon 11 mutation had PR and 2 had SD. One of the patients with exon 9 mutation had PR, 2 had SD, and 1 had PD. Two patients with the wild type GIST had PD. A total of 86 patients underwent surgery of which 85 underwent complete resection; 72 underwent anal preservation and 40 underwent local excision (LE). After PSM, patients who received neoadjuvant therapy had higher rates of LE (p = 0.001) and anal preservation (p = 0.033) than those of patients without neoadjuvant therapy. The median follow-up time was 37 months. Nine patients experienced recurrence and one patient died. The 3-year RFS and OS rates were 95.0% and 100%, respectively. After PSM, we found that there was no significant difference in RFS between patients who received or did not receive neoadjuvant therapy (p = 0.623). Univariate analysis showed postneoadjuvant tumor size (p = 0.469) and mitotic count (p = 0.294) were not associated with the RFS in patients who received neoadjuvant imatinib.

CONCLUSIONS

Neoadjuvant imatinib can shrink rectal GIST size, increasing the possibility of complete resection and anal preservation. Further studies are warranted to understand the long-term outcomes of rectal GISTs in patients receiving neoadjuvant imatinib.

The Combination of Neoadjuvant Therapy and Surgical Resection: A Safe and Effective Treatment for Rectal Gastrointestinal Stromal Tumors

Background

Rectal gastrointestinal stromal tumors (GISTs) are rare digestive tumors. The treatment methods of rectal GISTs are diverse, while no standardized treatment was recommended. The aim of this study was to report the treatment mode of rectal GISTs in our center.

Methods

Patients with pathologically confirmed rectal GISTs who received neoadjuvant therapy and surgical resection were retrospectively collected. Perioperative complications and long-term prognosis were evaluated.

Results

From January 2010 to December 2019, 36 patients were pathologically diagnosed with primary rectal GISTs. After excluding patients who were treated with surgery or imatinib alone, 21 patients received neoadjuvant therapy and surgery was enrolled. During neoadjuvant treatment, tumors shrank significantly (6.53cm to 4.68cm, p<0.001) without toxicities over grade 2. The total postoperative complication rate was 42.9% (all grade). R0 resection was achieved in 76.2% patients. Transanal resection had advantages on anus preservation and postoperative recovery. No patients died during the follow-up period, 4 patients relapsed and the relapse-free survival was 81.0%.

Conclusion

The combination of neoadjuvant therapy and surgical resection was a safe and effective treatment for rectal gastrointestinal stromal tumors.

Neoadjuvant therapy for gastrointestinal stromal tumors: A propensity score-weighted analysis

Retrospective and single-arm prospective studies have reported clinical benefit with neoadjuvant imatinib for GISTs. In the absence of randomized Phase III data, the impact of neoadjuvant systemic therapy (NAT) on survival compared to upfront resection (UR) remains unknown. We identified N = 16 308 patients within the National Cancer Database (2004-2016) who underwent resection of localized GIST of the stomach, esophagus, small bowel and colorectum, with or without ≥3 months of NAT. Inverse probability of treatment weighting adjusted for covariable imbalance among treatment groups. We estimated the effect of NAT on overall survival with a weighted time-dependent Cox proportional hazards model, and on 90-day postoperative mortality and R0 resection with weighted logistic regressions. Eight hundred sixty-five (5.3%) patients received NAT compared to 15 443 (94.7%) who underwent UR. Median NAT duration was 6.3 months. 53.7% of NAT patients were male vs 48.6% of UR patients, 67.3% vs 65.1% had primary gastric GIST and 72.8% vs 49.7% were at high risk. NAT patients had larger tumors and higher mitotic index. >3 months of NAT was associated with a significant survival benefit (weighted HR 0.85 [0.80-0.91]). 90-day postoperative mortality rate was 4/865 (0.5%) among NAT patients vs 346/15443 (2.2%). NAT was associated with lower odds of 90-day postoperative mortality. R0 resection rate was not significantly different between groups. In conclusion, despite higher risk features among NAT patients, this analysis suggests that NAT for localized GIST is associated with a modest survival benefit and lower risk of 90-day postoperative mortality, with no difference in likelihood of achieving an R0 resection.

Different Medical Features and Strategies of Large Rectal Gastrointestinal Stromal Tumor: A Multi-Central Pooling Analysis

Purpose

The rectum is a rare site for gastrointestinal stromal tumors (GISTs). Tumors in this critical anatomical site are prone to develop local recurrence, and this occurs at a high level even in low-risk tumors. Previous studies found that high-risk was the most common category in rectal gastrointestinal stromal tumors (RGISTs), and size was the most important factor affecting the long-term prognosis. We aimed to find out the most influential factor on clinical outcomes, and describe demographics, oncological differences, and surgical procedures in patients with poor prognosis.

Patients and Methods

Data on consecutive patients with RGIST, who were diagnosed at Peking University People’s Hospital, Shandong Province Hospital, and The First Affiliated Hospital of Shandong First Medical University from 2010 to 2020, were retrospectively evaluated. Further, a literature search was conducted by retrieving data from PubMed, EMBASE, and the Cochrane Library databases from inception up to March 20, 2020.

Results

In all, 50 patients were diagnosed with RGIST at three medical centers, and 86 published records were finally included in the literature review. Combined analysis of the whole individual patient data showed that 5.5 cm was deemed an appropriate cut-off value for L-RGIST, and that patients usually showed a male predominance (67.59%), younger age at onset (56.61 years), higher operative difficulty, and poorer prognosis.

Conclusion

Separation of patients with large RGIST from general patients may contribute to the recognition of the oncological characteristics and clinical management of this rare type of tumor.

Neoadjuvant tyrosine kinase inhibitors in rectal gastrointestinal stromal tumours: a provision for enhanced oncological and functional outcomes

Background

The role of tyrosine kinase inhibitors (TKI) in the neoadjuvant setting and the optimal duration of therapy remains poorly defined. As such, we aim to evaluate the impact of neoadjuvant TKI on oncological and functional outcomes in our cohort of patients with rectal GISTs.

Methods

A retrospective analysis of 36 consecutive patients who underwent treatment for rectal GIST at the National Cancer Centre Singapore from February 1996 to October 2017 was analysed. Surgical, recurrence and survival outcomes between the groups who underwent neoadjuvant therapy and those who underwent upfront surgery were compared.

Results

Patients who received neoadjuvant treatment had significantly larger tumours (median size 7.1 vs. 6.0 cm, p = 0.04) and lower mitotic count (> 10 per 50 HPF, 14 vs. 70%, p = 0.03) when compared with the non-neoadjuvant group. With TKI pre-treatment (median duration 8.8 months), majority of patients (82%) achieved at least partial response to the therapy coupled with a significant downsizing effect of up to 39% (median size of 7.1–3.6 cm), resulting in similar rates of sphincter-sparing surgery (75 vs. 76%, p = 0.94) when compared with the non-neoadjuvant group. In general, neoadjuvant group had lower rates of local recurrence (0 vs. 69%, p = 0.04) and higher overall survival (7.4 vs. 5.7 years, p = 0.03) as compared to the non-neoadjuvant group.

Conclusions

Neoadjuvant TKI has the benefit of downsizing unresectable rectal GIST to benefit from sphincter-sparing procedure and also confers protection against local recurrence and improves overall survival.

Transsacrococcygeal approach in rectal gastrointestinal stromal tumour resection: 10-year experience at a single centre

Background

The transsacrococcygeal (TSC) approach in rectal gastrointestinal stromal tumour (GIST) resection is clinically challenging and controversial, and we evaluated its value in the present study.

Methods

We enrolled patients who underwent rectal GIST resection by the TSC approach during 2008–2018. The clinicopathological index, surgical outcome, and prognosis were analysed. Prognostic information was obtained from medical records and follow-up data. Anal function was evaluated by the low anterior resection syndrome (LARS) score.

Results

Among 88 rectal GIST patients over the 10-year study period, 17 who underwent the TSC approach were analysed. The median age was 55 (range, 26–73) years. In total, 15 patients received preoperative imatinib neoadjuvant therapy for 232 (30–690) days. The tumours were exogenous in 14 patients and intramural in 3 patients. The mean initial tumour size and preoperative tumour size were 6.4±2.2 and 4.2±1.7 cm, respectively. The operative time and blood loss were 130.2±47.4 min and 44.6±36.0 mL, respectively. Of the 17 patients 7 had postoperative complications (within 30 days postoperatively), and the complications of 5 patients were cured by conservative treatment. Only 1 patient was lost to follow-up, and the others had a good oncological prognosis at recent follow-up evaluations. All patients had LARS scores ≤9 points at 1 year after the operation.

Conclusions

The TSC approach can result in a good oncological prognosis, usually does not affect anal function, and is particularly suitable for exogenous middle and low rectal GISTs. However, it might cause some controlled complications. Hence, careful patient selection is necessary for this operation.

Gastrointestinal stromal tumour of the rectum and intestinal obstruction: case report

We report the case of a 75-year-old female patient with a big tumour in the lower rectum with intestinal obstruction and lower gastrointestinal bleeding history who underwent a tumour biopsy under laparotomy and end colostomy at another hospital in Peru. She came to our institution for clinical evaluation with a pathology result of a rectal gastrointestinal stromal tumour. An extra elevator abdominoperineal resection was performed with tumour-free margins. The histology confirmed a high-grade (G2) rectal gastrointestinal stromal tumour with a mitotic index of 27/50. DOC-1 (+) and CD117 (+) in immunohistochemistry. Genomic DNA was extracted from the paraffin-fixed tumour sample, and c.1504_1509dupGCCTAT (p.Ala502_Tyr503dup) mutation was detected in exon 9 of the KIT gene. Imatinib 400 mg per day for 3 years was indicated as adjuvant treatment. Currently, she has a disease-free survival of 12 months.

Transanal endoscopic microsurgery with alternative neoadjuvant imatinib for localized rectal gastrointestinal stromal tumor: a single center experience with long-term surveillance

BACKGROUND

Transanal endoscopic microsurgery (TEM) is widely used in the treatment of local rectal lesions and helps avoid radical surgery. This study evaluated the management and outcome in a long-term followed cohort of patients with localized rectal GIST underwent TEM with alternative neodajuvant imatinib (nIM).

METHODS

A retrospective cohort study was undertaken of patients identified from a case database at Department of General Surgery, Peking Union Medical College Hospital (PUMCH) over a continuous period, from January 2006 to December 2017.

RESULTS

Over 12 years, 42 patients presented with a primary rectal GIST in PUMCH. Median age was 49 (range 27-77) years. Neoadjuvant imatinib (nIM) therapy was used in 16 patients, significantly reducing mean tumor size from 4.41 to 2.46 cm (p < 0.001) and mitotic index (p = 0.041). All of these patients underwent TEM with no tumor rupture, nIM therapy enabled sphincter-preserving surgery to be undertaken in 16 (16/42) patients who would otherwise have required abdominoperineal resection or pelvic exenteration for tumor clearance and all patients (42/42) achieve R0 resection and negative margin. Imatinib was also used as postoperative adjuvant treatment in 15 patients with high-risk GIST. Median follow-up was 77 (range 14-144) and overall survival is 100%. In 42 patients, Local recurrence (LR) occurred in 3 of 42 patients and 1 of 42 patients developed distant metastasis (DM) in 112 months after TEM. In the univariate analysis, mitotic index (p = 0.028), NIH risk categories (p = 0.047) were predictive feature of local relapse.

CONCLUSION

The application of nIM significantly decreased tumor size in large localized rectal GIST, which permitted TEM to preserve sphincter. The TEM procedure with alternative neoadjuvant imatinib therapy is a practicable treatment for patients with rectal GIST to preserve anus and have satisfied anal function.

Is nonanatomic rectal resection a valid therapeutic option for rectal gastrointestinal stromal tumors? A proposed decision algorithm

BACKGROUND AND OBJECTIVES

The best surgical approach to rectal gastrointestinal stromal tumors (GISTs) is still debated, and both nonanatomic rectal resection (NARR) and anatomic rectal resection (ARR) are applied. The aim of this study was to evaluate the feasibility and oncological outcomes of NARR and ARR for rectal GISTs (R-GISTs).

METHODS

Through a large French multicentre retrospective study, 35 patients were treated for R-GIST between 2001 and 2013. Patients who underwent NARR and ARR were compared.

RESULTS

There were 23 (65.7%) patients in group ARR and 12 (34.3%) in group NARR. Significantly more patients in the group with ARR had a neoadjuvant treatment (86%) with tyrosine kinase inhibitor (TKI) (imatinib) compared to those with NARR (25%) (p < .01). The median preoperative tumor size was significantly different between the groups without and with neoadjuvant TKI: 30 ± 23 mm versus 64 ± 44.4 mm, respectively (p < .001). Overall postoperative morbidity was 20% (n = 7) (26% for ARR vs. 8% for NARR; p = .4). After a median follow-up of 60.2 (3.2-164.3) months, the 5-year disease-free survival rates were 79.5% (confidence interval [CI] 95%: 54-100) for the NARR group and 68% (CI 95%: 46.4-89.7) for the ARR group (p = .697), respectively.

CONCLUSION

The use of NARR for small R-GIST's does not seem to impair the oncological prognosis.

Comparison of prognostic prediction models for rectal gastrointestinal stromal tumor

BACKGROUND

Rectal gastrointestinal stromal tumors (RGISTs) are biologically characterized tumors that are relatively rare. Thus, few studies have reported a specific prognostic system for this subset of tumors but integrated it into parallel systems, such as small intestine. Our aim is to develop a new predictive staging system nomogram (named FD-ZS system) for RGISTs.

RESULTS

Tumor size and mitotic rate were independent risk factors for tumor recurrence in RGISTs according to univariate and multivariate survival analyses. A prognostic predictive nomogram was developed, and a cut-off value of 65 points was calculated by X-tile to discriminate risk based on tumor size and mitotic rate. The C-indices for the FD-ZS, FD-Hou, NIH, and WHO systems were 0.706, 0.693, 0.687, and 0.680, respectively.

CONCLUSION

In the present study, a concise two-tier grading system (FD-ZS) for prognostic prediction of RGISTs that is simpler to several reported systems was developed, and a cut-off value was established to help RGIST patients determine whether to undergo adjuvant imatinib treatment.

METHODS

A nomogram was employed, and its predictive accuracy and discriminative ability were determined by concordance index (C-index) and calibration curve analyses. The nomogram was then compared with three stratification systems used for GISTs (FD-Hou, NIH, and WHO).

Preoperative imatinib and laparoscopic intersphincteric resection for large rectal gastrointestinal stromal tumor: A case report

•

Rectal GIST is a rare disease, and have often grown by the time of discovery due to lack of initially subjective symptoms.

•

A large rectal GIST often require extensive surgery which may lead to postoperative bowel dysfunction.

•

Preoperative chemotherapy with imatinib mesylate is effective for reducing the rectal GIST.

•

Laparoscopic intersphincteric resection may be a useful technique for giant rectal GIST, which enables anal preservation.

Introduction

Anus-preserving surgery for a large rectal gastrointestinal stromal tumor (GIST) may be difficult because of the location of the tumor in the pelvis. Therefore, rectal GIST might require extensive surgery, such as abdominoperineal resection. In recent years, preoperative imatinib therapy has been used to reduce tumor size and preserve the anus in some cases. However, there have been few reports of laparoscopic anal-preserving surgery for giant rectal GIST.

Presentation of a case

We present the case of a 55-year-old man who was referred to our hospital for examination of a 10-cm pelvic mass in the lower rectum. Endoscopic ultrasound with fine needle aspiration was performed, and the pathological findings resulted in a diagnosis of GIST. The mass had spread to the prostate and left levator ani muscles, and as a result, surgery was deemed difficult to perform without damaging the pseudo-capsule. Therefore, preoperative chemotherapy with imatinib mesylate (IM) was performed for 8 months. The mass was reduced to 7.8 cm, and laparoscopic intersphincteric resection (ISR) was performed.

Discussion

We also review prior cases of rectal GIST where patients had undergone anal-preserving surgery following preoperative chemotherapy with IM. Our case represented the largest tumor size in a review of cases of patients who had successful anal-preserving laparoscopic surgery following preoperative chemotherapy with IM.

Conclusion

Preoperative chemotherapy with imatinib mesylate was effective for reducing the rectal GIST, and laparoscopic ISR was useful for anal preservation, even when a tumor is large.

Radical excision versus local resection for primary rectal gastrointestinal stromal tumors. Cohort Study

BACKGROUND

Rectal gastrointestinal stromal tumor (GIST) is a rare digestive disease that originates in mesenchymal tissues and has malignant tendencies. At present, no standard treatment has been developed, and surgical approaches and the resection scope for rectal GISTs are controversial.

METHODS

The clinical, surgical, pathological and prognosis data of patients with primary rectal GIST in our center from January 2008 to January 2019 were retrospectively collected. The patients were divided into the radical excision (RE) and local resection (LR) groups.

RESULTS

A total of 537 GIST cases were collected, and 64 patients with primary rectal GIST were included in this study, including 25 cases in the RE group and 39 cases in the LR group. Tumor size (p = 0.013), distance from the anus (p = 0.038), National Institutes of Health (NIH) criteria (p = 0.001), preoperative adjuvant therapy (p = 0.016), postoperative adjuvant therapy (p = 0.028), blood loss (p = 0.048), operative time (p = 0.020) and the duration of hospitalization (p = 0.021) were statistically different between these 2 groups. The mean overall follow-up time was 46 months (range, 1-122 months). Disease recurrence was observed in 12 patients. No statistical differences were observed in 5-year disease-free survival (DFS) (93.3% vs 92.6%, p = 0.952) or overall survival (OS) (90.0% vs 91.6%, p = 0.832) between the RE group and the LR group.

CONCLUSION

Our study showed that LR has a similar prognosis to that of RE with respect to DFS and OS. For appropriate cases, LR has the advantages of a short operative time, less bleeding, and a quick recovery. Especially when combined with neoadjuvant therapy, LR can also achieve better perioperative efficacy. Therefore, LR is an effective method for resection of rectal GISTs and warrants clinical endorsement.

Transanal versus nontransanal surgery for the treatment of primary rectal gastrointestinal stromal tumors: a 10-year experience in a high-volume center

Background

Rectal gastrointestinal stromal tumor (GIST) is a rare digestive disease that has a distinct malignant tendency compared to that of gastric-derived GIST. At present, there is still no standard, and the surgical approach to rectal GIST is controversial.

Methods

The clinicopathological data and prognosis of rectal GIST patients admitted to the Sixth Affiliated Hospital of Sun Yat-sen University from 1998.01.01 to 2018.12.31 were collected retrospectively. All cases were divided into either the transanal (TA) group or the nontransanal (NTA) group.

Results

A total of 537 GIST cases were treated in 10 years, including 82 rectal GIST cases (64 cases underwent surgical resection, including 29 cases in the TA group and 35 cases in the NTA group). Preoperative neoadjuvant therapy (P=0.003), postoperative adjuvant therapy (P=0.017), operative time (P=0.013), blood loss (P=0.038), anus-preserver (P=0.048), 30-day complication rate (P=0.000), time to flatus (P=0.036), hospital stays (P=0.011), distance from the anus (P=0.047), tumor size (P=0.002), mitotic count (P=0.035) and National Institutes of Health (NIH) criteria (P=0.000) were significantly different between these two groups (all P<0.05). The median follow-up time was 41 (range, 1–122) months. Twelve patients had recurrence and metastasis, and 4 patients died. The 5-year disease-free survival (DFS) and overall survival (OS) were 74.4% and 91.2%, respectively, in the whole group. There were no statistically significant differences between the TA group and the NTA group at 5-year DFS (81.3% vs. 79.0%, P=0.243) and OS (88.7% vs. 93.3%, P=0.308).

Conclusions

In the treatment of rectal GIST, TA resection has a minimally invasive effect, less postoperative complications, high anal sphincter preservation rate, and R0 resection rate and a better prognosis. How to improve the proportion of neoadjuvant therapy and choose the appropriate cases for TA surgery is still a challenge.

Open transanal resection of low rectal stromal tumor following neoadjuvant therapy of imatinib mesylate: Report of 11 cases and review of literature

OBJECTIVE

The global burden of rectal gastrointestinal stromal tumor (GIST) is increasing. However, a limited number of reports hinder our ability to reach a definitive conclusion regarding the current treatment and prognosis. In this study, we outline our experience with open transanal resection of rectal GIST following neoadjuvant therapy with imatinib mesylate (IM).

PATIENTS AND METHODS

We retrospectively analyzed 11 patients with rectal GISTs treated with neoadjuvant IM therapy and open transanal resection between April 2011 and April 2017 in Shanghai Changzheng Hospital.

RESULTS

The patients had 400-600 mg/day IM once daily for a median of 7 months (range: 3-9 months). Tumor size, distance from the lower margin of the tumor to the anal verge (AV), mitotic rates and mutation analysis were assessed on pretreatment biopsy. After reassessment, all 11 patients underwent transanal R0 resection. With median follow-up of 28 months (range: 8-80 months), there was no tumor recurrence or metastasis.

CONCLUSION

Open transanal resection of rectal GIST after neoadjuvant treatment with IM has good surgical and survival outcomes.

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

BACKGROUND

The 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.

METHODS

Patients 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.

RESULTS

A 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).

CONCLUSION

CR 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.

Translational insights into gastrointestinal stromal tumor and current clinical advances

Gastrointestinal stromal tumor (GIST) is the most common soft tissue sarcoma of the gastrointestinal tract and, in the vast majority of cases, is characterized by activating mutations in KIT or, less commonly, PDGFRA. Mutations in these type III receptor tyrosine kinases (RTKs) account for over 85% of GIST cases, and the majority of KIT primary mutations respond to treatment with the tyrosine kinase inhibitor (TKI) imatinib. However, drug resistance develops over time, most commonly due to secondary kinase mutations. Sunitinib and regorafenib are approved for the treatment of imatinib-resistant GIST in the second and third lines, respectively. However, resistance to these agents also develops and new therapeutic options are needed. In addition, a small number of GISTs harbor primary activating mutations that are resistant to currently available TKIs, highlighting an additional unmet medical need. Several novel and selective TKIs that overcome known mechanisms of resistance in GIST have been developed and show promise in early clinical trials. Additional emerging targeted therapies in GIST include modulation of cellular signaling pathways downstream of KIT, antibodies targeting KIT and PDGFRA and immune checkpoint inhibitors. These advancements highlight the rapid evolution in the understanding of this malignancy and provide perspective on the encouraging horizon of current and forthcoming therapeutic strategies for GIST.

Transvaginal excision of rectal stromal tumors: case reports and a literature review

Background

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Rectal locations are very rare, and minimally invasive surgery is a good choice for the treatment of rectal GISTs.

Case presentation

Two women each had a mass located on the lower vaginal-rectal space as determined by transvaginal ultrasound (TV-US), pelvis MR imaging, and colonoscopy. The patients successfully underwent transvaginal excision. The spindle-shaped cells were found in pathological test. The immunohistochemical analysis showed that CD117 and Dog-1 were stained positively. These results confirmed the masses as GISTs. The postoperative period was uneventful without anal dysfunction. Two patients were received adjuvant treatment with imatinib after surgery.

Conclusion

Transvaginal excision could be a minimally invasive and safe alternative treatment in the management of rectal GISTs in lower locations.

Frequent rectal gastrointestinal stromal tumor recurrences in the imatinib era: Retrospective analysis of an International Patient Registry

INTRODUCTION

Rectal gastrointestinal stromal tumor (GIST) is rare and comprises about 3% of GIST.

METHODS

Registry data was collected by the Life Raft Group June 1976 to November 2017. All patients had a histologic GIST diagnosis. Demographic, clinicopathologic, and clinical outcome data were patient reported. Recurrence-free survival (RFS) was analyzed using the Kaplan-Meier method and Cox regression analysis.

RESULTS

Of 1798 patients in the database, 48 had localized rectal GIST (2.7%). Patients were frequently male (58.3%) and non-Hispanic whites (58.3%). Median age at diagnosis was 52 years. Most patients (77%) were diagnosed in the imatinib era (2001 to current). Over half (54.2%) of the cohort had mutation testing and all profiled tumors possessed KIT mutations (exon 9: 7.7%, exon 11: 88.5%, and exon 13: 3.8%). Most evaluable patients (26/28; 92.9%) had high-risk disease (modified NIH criteria) and nearly all patients (95.8%) received imatinib. Median follow-up was 8.8 years (range, 0.3-30.7) and overall RFS was 8.0 years (95% CI, 2.9-13.1). Thirty-two percent (12/37) of patients in the post-imatinib era developed recurrent disease. Diagnosis in the imatinib era was associated with improved RFS (HR = 0.22, 95% CI, 0.08-0.62; P = .004) in the multivariable model.

CONCLUSION

We find that disease recurrence remains prevalent in one-third of patients treated during the imatinib-era.

A Population-Based Study of the Incidence and Survival of Anorectal Gastrointestinal Stromal Tumor

Background

Gastrointestinal stromal tumor (GIST) is the most common type of primary gastrointestinal mesenchymal tumor, but GISTs arising in the anus and rectum are rare. This study aimed to undertake a population-based analysis of the incidence, patient demographics, and survival of patients with anorectal GIST compared with patients with GIST arising from other sites based on the Surveillance, Epidemiology, and End Results (SEER) Program database.

Material/Methods

The SEER database was used to identify all patients diagnosed with GIST and patients diagnosed with anorectal GIST from 2000 to 2015. The incidence of GIST, baseline clinical and demographic data, tumor stage, and patient survival data were analyzed, including overall survival (OS) and cancer-specific survival (CSS).

Results

A total of 277 patients with anorectal GIST were identified, with an incidence of 0.018 per 100,000. The incidence of GIST arising from other sites was 0.719 per 100,000. The median age at diagnosis for anorectal GIST was 57.5 years (range, 26–92 years), median tumor size was 6.55 cm (range, 0.6–20 cm), and surgery, but not chemotherapy, improved OS and CSS. Patients with anorectal GIST had a mean 1-year, 3-year, 5-year, and 10-year OS of 91.1%, 82.5%, 75.2%, and 58.5%, respectively. Patients with GIST arising at other sites had a mean 1-year, 3-year, 5-year, and 10-year OS of 88.3%, 76.4%, 66.5%, and 46.8%, respectively.

Conclusions

Anorectal GIST is a rare tumor that has a better outcome compared with GISTs arising at other sites in the gastrointestinal tract.

Possible Role and Therapeutic Target of PDGF-D Signalling in Colorectal Cancer

Platelet-derived growth factor D (PDGF-D) has been shown to mediate cellular processes of importance in cancer progression. This study aimed to investigate the expression and putative involvement of PDGF-D signaling in colorectal carcinogenesis. PDGF-D was expressed in vascular endothelial cells in tumor and normal tissues. PDGF-D stimulation of cells altered genes of importance in carcinogenic processes. In addition, PDGF-D increased the proliferation rate while imatinib inhibited these effects. PDGF-D and its PDGF receptor beta (PDGFR-β) are expressed in colorectal cancer and blockage of PDGF-D/PDGFR-β signaling using tyrosine kinase inhibitors, such as imatinib, might be important in inhibiting tumor-promoting actions.

Neoadjuvant and adjuvant therapy for gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GIST) are rare and mesenchymal in origin with a yearly incidence of 10-15 cases per million people. If it is technically resectable, surgical resection is the mainstay of therapy regardless of tumor location,. Although complete (R0) resection can be achieved in up to 85% of patients with primary disease, approximately 50% of patients experience recurrence or metastases within 5 years of primary resection. Moreover, prior to 2000, the prognosis of patients with advanced, inoperable GIST was poor because the molecular mechanism had not sufficiently been elucidated, thus effective therapy was lacking. The tyrosine kinase inhibitor imatinib, which selectively inhibits tyrosine kinase KIT, has shown substantial clinical benefit for patients with GIST. In clinical trials, imatinib treatment resulted in response rates of 40%-55% and longer progression-free survival for patients with a KIT-positive unresectable or metastatic GIST. Furthermore, recent clinical trials have shown that giving imatinib after curative resection for high-risk cases prolonged recurrence-free survival and overall survival in an adjuvant setting. Several clinical trials of imatinib treatment in a neoadjuvant setting are ongoing; however, in clinical settings, there are problems to resolve, such as optimal agents, duration of administration, and postoperative management. In this review, we discuss the application of surgical options, combined with adjuvant/neoadjuvant or perioperative imatinib treatment and their potential impact on survival for patients with primary, recurrent, or metastatic GIST.

Prolonging Gastrointestinal-Stromal-Tumor-free life, an optimal suggestion of imatinib intervention ahead of operation

Background: Imatinib has been regarded as the first successful synthetic small molecule targeting at blocking tyrosine kinase. Its high efficacy stabilized disease in above 80% of chronic myeloid leukemia (CML) patients over 10 years survival. Due to the similar canceration of gastrointestinal stromal tumor (GIST) as to CML, imatinib has been approved to be used as first-line treatment. Study design: Our retrospective study was proposed to enroll 191 GIST patients with larger tumor size (≥8 cm) who preoperative accepted imatinib from those with direct operation. Analysis included demographics, cancer specific survival and relationship of their risk factors. Results: Male patients and gastrointestinal (GI) tract location took higher proportion in total cases, detection of KIT mutant took 89.7% among all traceable genetic testing. Patients with preoperative imatinib can achieve higher cancer specific survival (CSS) after both in 1 year and 3 years duration than their counterpart. Tumor size above its threshold of 8 cm would be a hazardous factor for poor prognosis. Conclusion: In conclusion, as for regressing tumor progression and creating operative chance, preoperative imatinib should be considered for the patients with high risk, although the precise duration of this intervention needs further validation.

Neoadjuvant Therapy to Downstage the Extent of Resection of Gastrointestinal Stromal Tumors

INTRODUCTION

Gastrointestinal stromal tumors (GIST) are rare malignant tumors in terms of incidence, and they are not linked to specific symptoms. Often, primary tumors, particularly of the stomach, rectum, or rectovaginal space, are quite large when detected, and multivisceral resection seems to be the treatment of choice as the mainstay of therapy is complete tumor removal. If a gain-of-function mutation in the KIT gene is present, drug therapy with receptor tyrosine kinase inhibitors (RTKIs) might significantly downstage primary GIST tumors.

METHODS

A review of the literature was performed to identify the current evidence for preoperative treatment of GIST regarding toxicity, efficacy, and oncological outcome, including mutational data from our own database.

RESULTS

Four phase II as well as several cohort studies showed acceptable toxicity and no increased perioperative morbidity of preoperative imatinib. Progressive disease during preoperative treatment was a rare event, and partial response was achieved in 40-80% of all patients. For methodological reasons, the trials cannot prove an oncological long-term superiority of preoperative treatment.

CONCLUSION

Preoperative therapy with imatinib is safe and recommended for patients with locally advanced GIST. Neoadjuvant imatinib therapy may enable less invasive and organ-sparing surgery, avoid tumor rupture during extensive resectional procedures, and improve the quality of perioperative RTKI treatment.

Gastrointestinal Stromal Tumors of the Distal Gastrointestinal Tract

Gastrointestinal stromal tumors (GISTs) are rare in occurrence, but comprise the most common mesenchymal tumors of the gastrointestinal tract and affect between 15 and 20 individuals per million per year. Due to recent advancements in molecular classification of these tumors, medical therapy has provided improved outcomes to a historically surgically managed disease. This review article briefly discusses the molecular characteristics, medical and surgical therapies, and future of GIST management.

Radiotherapy for Gastrointestinal Stromal Tumors

OBJECTIVE

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal tumors of the gastrointestinal tract, which frequently cause intraabdominal metastases. The current standard of care is surgery for localized cases, and adjuvant imatinib is recommended for tumors with a high risk of recurrence. To date, radiotherapy has not been commonly accepted as a part of multimodality treatment approach other than palliation. However, recently published case reports and some small series suggest that radiotherapy is a valuable option for controlling locally progressive, drug-resistant disease. The aim of this review is to provide a viewpoint from a radiation oncologist concerning the management of GISTs, especially rectal GIST, and clarify the role and technical aspects of radiotherapy in the treatment approach.

DATA SOURCES

A comprehensive search in PubMed using the keywords "radiotherapy for rectal GIST" and "rectal GIST" was undertaken. The literature search included the related articles after 1995.

STUDY SELECTION

The main articles including rectal GIST case reports and GIST series containing rectal cases were the primary references.

RESULTS

Surgery is the mainstay of treatment. However, to date, radiotherapy is included in the multidisciplinary treatment strategy of rectal GISTs in some circumstances with palliative, adjuvant, or definitive intent using different treatment doses and fields.

CONCLUSIONS

Recently reported long-term local control rates indicate that GIST is a radiosensitive disease. This makes radiotherapy a valuable alternative in GIST management with curative intent, especially in patients who (1) cannot tolerate or are resistant to chemotherapy agents, (2) have an unresectable disease, (3) have a gross or microscopic residual disease after surgery, and (4) have a recurrent disease.

Management of a case of high-risk gastrointestinal stromal tumor in rectum by transanal minimal invasive surgery

BACKGROUND

Rectal gastrointestinal stromal tumor (GIST) is a very rare tumor of gastrointestinal tract. Surgical management of rectal GIST requires special attention for preserving of anal and urinary functions. Transanal minimal invasive surgery (TAMIS) is a well-developed minimally invasive technique for local excision of benign and early malignant rectal tumors; however, the application of TAMIS for rectal GIST is rarely and inadequately reported. We report the novel application of TAMIS for rectal GIST with considerations for anal and urinary functions.

CASE PRESENTATION

A 67 years old female, who presented with history of per rectal bleeding, was diagnosed with submucosal GIST of 4.5 cm in diameter at right posterior wall of 7 cm from anal verge. Histology of biopsy showed abundant spindle-shaped cells arranged in bundles that were positive for CD34 and negative for C-Kit, desmin, smooth muscle actin (SMA), and S-100. The tumor was excised by TAMIS successfully. Final histopathology showed pT2 tumor with C-Kit positive and mitosis count 10 per 50 HPF. Postoperative period was uneventful, and she was discharged on adjuvant imatinib mesylate for 3 years.

CONCLUSION

TAMIS can be used safely in the management of rectal GIST after appropriate evaluation of tumor size, extent, location, and experience of operating surgeon.

Gastrointestinal stromal tumors: A multidisciplinary challenge

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors located in the alimentary tract. Its usual manifestation is gastrointestinal bleeding. However, small asymptomatic lesions are frequently detected as incidental finding. Characteristically, most GISTs (> 95%) are positive for the KIT protein (CD117) by IHC staining and approximately 80%-90% of GISTs carry a mutation in the c-KIT or PDGFRA genes. Mutational analysis should be performed when planning adjuvant and neoadjuvant therapy, due to its possible resistance to conventional treatment. The arise of tyrosine kinase inhibitor has supposed a revolution in GISTs treatment being useful as adjuvant, neoadjuvant or recurrence disease treatment. That is why a multidisciplinary approach to this disease is required. The correct characterization of the tumor at diagnosis (the diagnosis of recurrences and the evaluation of the response to treatment with tyrosine kinase inhibitors) is fundamental for facing these tumors and requires specialized Endoscopist, Radiologists and Nuclear Medicine Physician. Surgery is the only potentially curative treatment for suspected resectable GIST. In the case of high risk GISTs, surgery plus adjuvant Imatinib-Mesylate for 3 years is the standard treatment. Neoadjuvant imatinib-mesylate should be considered to shrink the tumor in case of locally advanced primary or recurrence disease, unresectable or potentially resectable metastasic tumors, and potentially resectable disease in complex anatomic locations to decrease the related morbidity. In the case of Metastatic GIST under Neoadjuvant treatment, when there are complete response, stable disease or limited disease progression, complete cytoreductive surgery could be a therapeutic option if feasible.

Management of rectal gastrointestinal stromal tumor

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the gastrointestinal tract. However, rectal GIST is rare, the incident rate of it is approximately 5% of all GISTs. Rectal GIST symptoms generally include bleeding and/or pain and occasionally, urinary symptoms. Immunohistochemical evaluation finds that most rectal GIST tumors are CD117 (KIT) positive, and are sometimes CD34, platelet-derived growth factor receptor alpha (PDGFRA), smooth muscle actin, S-100, or vimentin positive. The National Institutes of Health (NIH) classifies rectal GIST as very-low risk, low risk, intermediate risk, or high risk, and the frequencies have been estimated as 0-23.8% for very-low risk, 0-45% for low risk, 0-34% for intermediate risk, and 21-100% for high risk tumors. The first-line treatment for localized GIST is curative resection, but is difficult in rectal GIST because of anatomical characteristics such as the deep, narrow pelvis and proximity to the sphincter muscle or other organs. Several studies noted the efficacy of the minimally invasive surgery, such as trans-anal, trans-sacral, trans-vaginal resection, or laparoscopic resection. The appropriate surgical procedure should be selected depending on the case. Imatinib mesylate (IM) is indicated as first-line treatment of metastatic or unresectable GIST, and clinical outcomes are correlated with KIT mutation genotype. However, the KIT mutation genotypes in rectal GIST are not well known. In this review, as in other GISTs, a large proportion (59-100%) of rectal GISTs carry exon 11 mutations. Although curative resection is indicated for localized rectal GIST, a high rate of local recurrence is a problem. Multimodal therapy including perioperative IM may improve postoperative outcomes, contributing to anus-preserving surgery. Moreover, KIT mutation analysis before IM treatment is important. This review summarizes current treatment strategies for rectal GIST.

Neoadjuvant therapy for gastrointestinal stromal tumor

Molecular-targeting therapy using tyrosine kinase inhibitor imatinib mesylate is effective for metastasis/recurrent gastrointestinal stromal tumors (GISTs). Likewise, imatinib would be effective in the neoadjuvant therapy for high-risk GIST. Neoadjuvant therapy may have the potential to increase the complete resection rate and to avoid the surgical rupture by decreasing the tumor size. Thereby, it is expected that improvement of recurrence rate and survival rate can be obtained by neoadjuvant therapy. Neoadjuvant therapy is also expected to be favored from the viewpoint of organ/function preservation by tumor shrinkage. The existing results of clinical trials established the feasibility of neoadjuvant imatinib therapy. However, proof of the survival effectiveness of neoadjuvant imatinib therapy has not been sufficiently demonstrated. The aim of this article is to introduce previous evidence and strategies regarding neoadjuvant therapy for GIST.