Prognostic factors of primary gastrointestinal stromal tumors: a cohort study based on high-volume centers

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.

A radiomics-clinical combined nomogram-based on non-enhanced CT for discriminating the risk stratification in GISTs

PURPOSE

To discriminate the risk stratification in gastrointestinal stromal tumors (GISTs) by preoperatively constructing a model of nonenhanced computed tomography (NECT).

METHODS

A total of 111 GISTs patients (77 in the training group and 34 in the validation Group) from two hospitals between 2015 and 2022 were collected retrospectively. One thousand and thirty-seven radiomics features were extracted from non-contract CT images, and the optimal radiomics signature was determined by univariate analysis and LASSO regression. The radiomics model was developed and validated from the ten optimal radiomics features by three methods. Covariates (clinical features, CT findings, and immunohistochemical characteristics) were collected to establish the clinical model, and both the radiomics features and the covariates were used to build the combined model. The effectiveness of the three models was evaluated by the Delong test.

RESULTS

The experimental results showed that the clinical models (75.3%, 70.6%), the radiomics models (79.2%, 79.4%) and the combined models (81.8%, 82.4%) all had high accuracy in predicting the pathological risk of GIST in both training and validation groups. The AUC values of the combined models were significantly higher in both the training groups (0.921 vs 0.822, p= 0.032) and the validation groups (0.913 vs 0.792, p= 0.019) than that of the clinical models. According to the calibration curve, the combined model nomogram is clinically useful.

CONCLUSIONS

The clinical-radiomics combined model and based on NECT performed well in discriminating the risk stratification in GISTs. As a quantitative technique, radiomics is capable of predicting the malignant potential and guiding treatment preoperatively.

Survival outcome of local versus radical resection for jejunoileal gastrointestinal stromal tumors: a propensity score-matched population-based analysis

PURPOSE

Survival after local resection (LR) versus radical resection (RR) has been revealed comparable for patients with rectal and duodenal gastrointestinal stromal tumors (GISTs), but is unknown for jejunoileal (JI) GISTs. This study aimed to compare the long-term survival between patients with JI GISTs who underwent LR and RR, and to find out the prognostic factors for JI GISTs.

METHODS

Patients diagnosed with JI GISTs in 1975-2019 were identified from Surveillance, Epidemiology, and End Results (SEER) database and grouped according to surgical modality. Propensity score matching (PSM) was performed to balance the LR and RR groups. Overall survival (OS) and disease-specific survival (DSS) were compared in the full and matched cohorts using Kaplan-Meier (KM) analysis. Subgroup sensitivity analyses were also performed. Risk factors associated with DSS were analyzed in multivariate Cox analysis following model selection.

RESULTS

1107 patients diagnosed with JI GISTs were included in the study cohort. After PSM, OS and DSS were comparable in LR and RR groups. Consistently, the two groups had similar DSS in all subgroup analyses. Moreover, multivariate Cox analysis identified lymphadenectomy, older age, larger tumor size, distant metastasis, high and unknown mitotic rate, but not LR, as independent prognostic risk factors for JI GISTs.

CONCLUSIONS

We conducted the first population-based comparison between the effect of different surgical modes on survival for patients with JI GISTs. LR can be carried out safely without compromising oncological outcome, and should be considered as a treatment option in selected patients with JI GISTs.

Gastro-intestinal stromal tumor (GIST): Experience from a tertiary care center in a low resource country

Objectives

The aim of this retrospective study was to review the overall survival (OS) and disease-free survival (DFS) of GISTs treated surgically at our center over the past decade.

Material and Methods

We undertook a 12-year retrospective review of our experience in treating this condition with a focus on long-term outcomes of treated patients in a resource-constrained environment. Incomplete follow-up information continues to be a major problem with studies conducted in low resource settings, and in order to overcome this, we undertook telephonic contact with patients or their relatives to get the necessary information about their clinical status.

Results

Fifty-seven patients with GIST underwent surgical resection during this period of time. The stomach was the most common organ involved in the disease, with 74% of the patients. Surgical resection was the main treatment approach, with R0 resection possible in 88%. Nine percent of the patients were given Imatinib as neoadjuvant treatment and 61% were offered the same, as adjuvant therapy. The duration of adjuvant treatment changed from one year to three years over the study period. Pathological risk assessment categorized the patients as Stage I, 33%; Stage II, 19%; Stage III, 39%; and Stage IV, 9%. Of the 40 patients who were at least three years from surgery, 35 were traceable giving an 87.5%, overall three-year survival. Thirty-one patients (77.5%) were confirmed to be disease-free at three years.

Conclusion

This is the first report of mid-long-term outcomes of the multimodality treatment of GIST from Pakistan. Upfront surgery continues to be the main modality. OS & DFS in resource-poor environments can be similar to those seen in a better-structured healthcare setting.

Gastric Pouch Gastrointestinal Stromal Tumour Post-Roux-en-Y Gastric Bypass: A First Reported Case

Gastric gastrointestinal stromal tumour is an extremely rare condition to occur after bariatric surgery. To the authors’ knowledge, only two cases of gastric gastrointestinal stromal tumours after Roux-en-Y gastric bypass have been reported in the medical literature, both occurring in the excluded gastric remnant. Herein, the authors report the third case of gastric gastrointestinal stromal tumour post-Roux-en-Y gastric bypass, and the first case to occur in the gastric pouch, which was managed surgically by laparoscopic resection. From here, combining the observations of clinicians treating and following up patients post-bariatric surgery in an international database will be beneficial to patients, and aid in development of surveillance guidelines.

Prognostic Nomogram for Gastrointestinal Stromal Tumors after Surgery Based on the SEER Database

We aimed to determine prognostic factors and develop an effective and practical nomogram for predicting cancer-specific survival in gastrointestinal stromal tumor (GIST) patients. Postoperative data were obtained from the SEER database (2000-2018). Patients were divided into training and validation cohorts at random (7 : 3). Prognostic factors were screened, and a prognostic nomogram was established using log-rank testing and Cox regression. We used DCA, ROC curves, C-index, and calibration curves to evaluate our model's predictive performance. The clinical value of the nomogram and the modified National Institute of Health (M-NIH) classification were compared using the NRI and IDI. The Kaplan-Meier method was applied to examine survival by risk group, and log-rank tests were applied to compare variations in survival curves. Independent prognostic risk factors associated with cancer-specific survival on multivariate Cox proportional hazards regression analysis were age, race, and tumor location, size, grade, and stage. Clinically relevant variables need to be considered in addition to statistically significant variables when developing prognostic models to aid clinical decision-making. We included two additional variables (mitotic rate and chemotherapy) when constructing the prognostic model. The C-index was 0.766 (95% confidence interval (CI): 0.737-0.794) in the training cohort and 0.795 (95% CI: 0.754-0.836) in the internal validation group suggesting robustness. The areas under the ROC curve for three-year and five-year survival were >0.700, indicating satisfactory discrimination. The calibration curves showed good agreement between the predictions of the nomogram and the actual results. The NRI (0.346 for 3-year and 0.265 for 5-year cancer-specific survival for patients with GIST (GSS) prediction; validation cohort: 0.356 for 3-year and 0.246 for 5-year GSS prediction) and IDI values (0.047 for 3-year and 0.060 for 5-year GSS prediction; validation cohort: 0.071 for 3-year and 0.084 for 5-year GSS prediction) suggested that the established nomogram performed significantly better than the M-NIH classification. The DCA indicated that the nomogram was clinically useful and had a high discriminative ability in identifying patients who were at high risk of poor outcomes. According to nomogram findings, patients were divided into three groups (high, moderate, and low risk), with significantly different prognoses in both cohorts. Our nomogram satisfactorily predicted survival in postsurgical GIST patients, which may assist clinicians to evaluate the postoperative status and guide subsequent treatments.

The analysis of prognostic factors of primary small intestinal gastrointestinal stromal tumors with R0 resection: A single-center retrospective study

OBJECTIVE

We aim to assess factors that affect overall survival in patients with primary small intestinal gastrointestinal stromal tumors (GISTs) who had undergone R0 resection.

METHOD

A retrospective analysis reviewed the data of 82 consecutive confirmed GIST patients at a single medical center in China from January 2012 to June 2020. The survival curve was estimated using the Kaplan-Meier method, and independent prognostic factors were confirmed using the Cox regression model.

RESULTS

A total of 82 patients were included in the study: 42 men and 40 women, the mean age was 59 years old (23-83 years old). Tumors were commonly found in the jejunum (46.3%), ileum (20.7%), and duodenum (32.9%). The median tumor size was 6.0 cm (range: 1.0-15.0 cm). The number of mitoses per one 50 high-power field was used to define the mitotic rates. In our present study, 56 patients presented a mitotic rate ≤5 (68.3%) and 26 patients showed a rate >5 (31.7%) at the time of diagnosis. All patients accepted tumor resection without lymph node resection. The positivity rate was 97.6% for CD117, 96.3% for delay of germination 1, 65.9% for CD34, 6.1% for S-100, and 59.8% for smooth muscle actin using immunohistochemistry. Tumor size, tumor rupture, Ki67 index, mitotic index, and postoperative imatinib were independent prognostic factors for small intestinal GISTs.

CONCLUSIONS

In this study, larger tumor size, high Ki67 index, high mitotic index, the occurrence of tumor rupture, and use of imatinib were independent unfavorable prognostic indicators.

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.

Clinical and Prognostic Significance of Tumor-Infiltrating CD8+ T Cells and PD-L1 Expression in Primary Gastrointestinal Stromal Tumors

Purpose

Immunotherapy for gastrointestinal stromal tumors (GISTs) remains a clinical challenge. The present study aimed to explore the clinical and prognostic significance of immune cell infiltration and PD-L1 expression in GISTs.

Methods

A total of 507 clinical tissue specimens of primary GISTs were collected for immunohistochemical analysis of immune cell infiltration and PD-L1 expression. Influencing factors of survival were evaluated by Kaplan–Meier analysis. Univariate and multivariate analyses were performed using the Cox regression model.

Results

There were significant differences in sex, tumor location, size, mitotic index, NIH risk grade, and cell morphology between different gene mutation types of GISTs. Immune cell infiltration in GISTs mainly involved macrophages and T cells. PD-1 was expressed in 48.5% of the tissue specimens, and PD-L1 expression was detected in 46.0% of the samples. PD-L1 expression was negatively correlated with the tumor size and mitotic index but positively correlated with the number of CD8+ T cells. There were significant differences in the number of CD8+ T cells between different gene mutation types. Wild type-mutant GISTs were enriched with CD8+ T cells as compared with KIT- and PDGFRA-mutant GISTs. The number of CD8+ T cells was higher in non-gastric GISTs. PD-L1 and CD8+ T cells were independent predictors for better relapse-free survival of GISTs.

Conclusions

PD-L1 expression is a predictive biomarker for better prognosis of GISTs. Non-gastric GIST patients with wild-type mutations may be the beneficiaries of PD-1/PD-L1 inhibitors.

DOG1 expression is common in human tumors: A tissue microarray study on more than 15,000 tissue samples

DOG1 (Discovered on GIST1) is a voltage-gated calcium-activated chloride and bicarbonate channel that is highly expressed in interstitial cells of Cajal and in gastrointestinal stromal tumors (GIST) derived from Cajal cells. To systematically determine in what tumor entities and normal tissue types DOG1 may be further expressed, a tissue microarray (TMA) containing 15,965 samples from 121 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. DOG1 immunostaining was found in 67 tumor types including GIST (95.7%), esophageal squamous cell carcinoma (31.9%), pancreatic ductal adenocarcinoma (33.6%), adenocarcinoma of the Papilla Vateri (20%), squamous cell carcinoma of the vulva (15.8%) and the oral cavity (15.3%), mucinous ovarian cancer (15.3%), esophageal adenocarcinoma (12.5%), endometrioid endometrial cancer (12.1%), neuroendocrine carcinoma of the colon (11.1%) and diffuse gastric adenocarcinoma (11%). Low level-DOG1 immunostaining was seen in 17 additional tumor entities. DOG1 expression was unrelated to histopathological parameters of tumor aggressiveness and/or patient prognosis in cancers of the breast (n = 1002), urinary bladder (975), ovary (469), endometrium (173), stomach (233), and thyroid gland (512). High DOG1 expression was linked to estrogen receptor expression in breast cancer (p < 0.0001) and absence of HPV infection in squamous cell carcinomas (p = 0.0008). In conclusion, our data identify several tumor entities that can show DOG1 expression levels at similar levels as in GIST. Although DOG1 is tightly linked to a diagnosis of GIST in spindle cell tumors, the differential diagnosis is much broader in DOG1 positive epithelioid neoplasms.

A Retrospective Study of Postoperative Outcomes in 98 Patients Diagnosed with Gastrointestinal Stromal Tumor (GIST) of the Upper, Middle, and Lower Gastrointestinal Tract Between 2009 and 2019 at a Single Center in Poland

BACKGROUND Gastrointestinal stromal tumors (GISTs) arise in the smooth muscle pacemaker interstitial cells of Cajal, or similar cells. The aim of this retrospective study between 2009 and 2019 from a single center in Poland was to assess the selected prognostic factors (location, tumor size, mitotic index, body mass index (BMI), length of hospital stay, age, sex, and coexistent neoplasm) and to investigate postoperative outcomes in 98 patients with GIST of the upper, middle, and lower gastrointestinal tract. MATERIAL AND METHODS Between 2009 and 2019, 98 patients (50 women and 48 men) with an average age of 63.8 years (range from 38 to 90 years) were operated on for GIST in the Department of Gastrointestinal Surgery in Katowice, Poland. Based on the intraoperative and postoperative investigations, the tumor size and mitotic index were determined in each case. RESULTS A statistically significant correlation between age and mitotic index (MI) was found (p=0.02). The higher the MI, the younger the age of the patients. However, regardless of sex, younger patients had a tendency to survive longer. A >60-year-old male patient's probability of survival was around 65% after 40 months. Higher mitotic index was also associated with larger tumor size (p<0.0001). Female patients had a tendency to survive longer than males. CONCLUSIONS The findings from this small retrospective study support the importance of preoperative evaluation and frequent postoperative follow-up for patients with GIST of the gastrointestinal tract, particularly in older male patients, and patients with malignant comorbidities, which are associated with increased mortality.

Controversies in EUS: Do we need miniprobes?

This is the fifth in a series of papers entitled "Controversies in EUS." In the current paper, we deal with high-resolution catheter probes, otherwise known as EUS miniprobes (EUS-MPs). The application of miniprobes for early carcinomas in the entire intestinal tract, for subepithelial lesions, and for findings in the bile duct and pancreatic duct as well as endobronchial use is critically discussed. Submucous lesions, especially in the colon, but also early carcinomas in special cases are considered the most important indications. The argument is illustrated by numerous examples.

Evaluation of Ki67 Index in Endoscopic Ultrasound-Guided Fine Needle Aspiration Samples for the Assessment of Malignancy Risk in Gastric Gastrointestinal Stromal Tumors

BACKGROUND

The risk of malignancy in resected gastrointestinal stromal tumors (GISTs) depends on tumor size, location, and mitotic index. Reportedly, the Ki67 index has a prognostic value in resected GISTs. We aimed to analyze the accuracy of endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) samples with reference to Ki67 index, using surgical specimens as the gold standard.

METHODS

Fifty-five patients who underwent EUS-FNA followed by surgical resection for gastric GISTs were retrospectively analyzed. Patients' age and sex; tumors' size and location; mitotic index, cell type, cellularity, pleomorphism, presence of ulceration, hemorrhage, necrosis, mucosal or serosal invasion, growth pattern, and Ki67 index based on pathology were investigated.

RESULTS

Location in fundus, ulceration, hemorrhage, mucosal invasion, and Ki67 index in surgical specimens were significant in predicting high-risk groups (p < 0.05) on univariate analysis. Frequency of bleeding (p = 0.034) and the Ki67 index (p = 0.018) were the only independent significant factors in multivariate analysis. The optimal cutoff level of Ki67 was 5%, with 88.2% sensitivity and 52.8% specificity (p = 0.021). The mean Ki67 index was lower in EUS-FNA samples than in surgical specimens (2% [1-15] versus 10% [1-70], p = 0.001). The rank correlation coefficient value of Ki67 was 0.199 (p = 0.362) between EUS-FNA and surgical samples and showed no reliability for EUS-FNA samples.

CONCLUSION

The Ki67 index in resected specimens correlated with high-risk GISTs, although it had no additive value to the current criteria. The Ki67 index in EUS-guided FNA samples is not a reliable marker of proliferation in GISTs.

Unusual presentations, management and outcomes of gastric stromal tumors: a single-center case series

Background

Gastrointestinal stromal tumors (GISTs) are uncommon mesenchymal tumors of the gastrointestinal tract. This study explores the safety of laparoscopy and the long-term oncological outcome in gastroesophageal GIST treatment.

Methods

A prospectively maintained single-institution database was examined. The variables collected were patient demographics and comorbidities, surgical access (laparoscopic/open), type of surgery, length of stay, and complications.

Results

A total of 69 patients underwent GIST resection between January 2011 and June 2018, of whom 56.5% were male; the median age was 68 years (interquartile range 60-76). The majority of patients (78.3%, n=54/69) had a laparoscopic resection. Median length of stay was 6 days in the laparoscopic group and 9 days in the open group (P=0.003). Most patients had wedge excision (n=57/69, 82.6%), while 12 patients (17.4%) required a gastrectomy (one a Merendino type). All patients had an R0 resection and 1 patient (1.4%) had a recurrence, despite having a low-risk grade original tumor with negative margins. Patients in the open group had a significantly higher proportion of patients with a high-risk tumor (50%) compared to the laparoscopic group (3.7%, P=0.001). The mean survival was 92.7 months (95% confidence interval 86.3-99.2). Survival was better in the laparoscopic group (100.4 months) compared with the open group (55.1 months, P<0.001).

Conclusion

Laparoscopic gastric GIST resection is an oncologically safe alternative to open surgery and is associated with a shorter hospital stay with no difference in complication rates or recurrence rates.

Gastrointestinal stromal tumor of the excluded stomach after Roux-en-Y gastric bypass: A case report and literature review

•

This is the second reported case of GIST post-RYGB.

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GISTs generally present good prognosis after surgical resection.

•

The case reported after RYGB did not present the patient follow-up.

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The case reported after gastric banding presented recurrence 3 years after resection.

Background

Gastric cancer is an extremely rare condition to occur after bariatric surgery, and most of the reported cases are adenocarcinomas. Regarding gastrointestinal stromal tumors (GISTs), there are only two reported cases occurring after bariatric surgery (one after gastric banding and the other following Roux-en-Y gastric bypass (RYGB)).

Case presentation

A 48-year-old woman with previous history of obesity and type 2 diabetes, treated with a Roux-en-Y gastric bypass 2 years earlier, was referred to our center due to complains of diffuse abdominal pain and distension associated with asthenia. Magnetic resonance imaging showed a cystic-solid mass located in the right hypochondrium, measuring 19.5 × 13.5 × 16 cm, suggesting the diagnosis of a retroperitoneal tumor. Based on these findings, a laparotomy, evidencing that the larger cystic-solid tumor was originating from the excluded stomach post-RYGB. The gastrectomy of the excluded stomach was performed aside with a conventional cholecystectomy. Histopathology and immunohistochemistry confirmed to be a gastric GIST with epithelioid cells. Currently, 12 months after surgery, the patient presents no signs of recurrence.

Conclusion

This is the second case of gastric GIST occurring after RYGB to be reported in the literature.

Adjuvant systemic therapy for small bowel gastrointestinal stromal tumor (GIST): Is there a survival benefit after R0 resection?

BACKGROUND

The utility of adjuvant systemic therapy in small bowel gastrointestinal stromal tumor remains unclear.

METHODS

We queried the National Cancer Data Base for individuals having enterectomy to negative margins for small bowel gastrointestinal stromal tumor between 2010 and 2015. Subjects were categorized by tumor size (2.1-5 cm, 5.1-10 cm, >10 cm) and histologic grade (≤5 mitoses/50 high-power field and >5 mitoses/50 high-power field). Cox proportional hazard analysis was performed to evaluate the association between adjuvant therapy and overall survival.

RESULTS

One thousand five hundred fifty-nine patients met the inclusion criteria. On univariate comparison to resection alone, adjuvant therapy was associated with improved overall survival for individuals with high-grade tumors of intermediate and large size (85% vs 48%, P = .010; 75% vs 47%, P = .003) but not for those with high-grade tumors of small size or low-grade tumors of any size. On multivariable analysis adjusted for age, comorbid disease state, and tumor size, adjuvant therapy was independently associated with reduced risk of mortality for high-grade (hazard ratio 0.37, 95% confidence interval: 0.21-0.64) but not low-grade tumors.

CONCLUSION

Adjuvant therapy after R0 resection for small bowel gastrointestinal stromal tumor should be administered after careful consideration of the size and grade of a patient's tumor.

The current status of and prospects in research regarding gastrointestinal stromal tumors in China

China still lacks statistical data regarding the incidence of gastrointestinal stromal tumors (GISTs). Data from 3 regions have demonstrated that the incidence of GISTs in China is similar to that in the United States. Furthermore, no significant differences between both nations with regard to epidemiological characteristics and genotyping of GISTs have been reported. Chinese physicians are demonstrating an increased interest in studies regarding GISTs. Currently, to the authors' knowledge, China publishes the most research articles regarding GIST annually worldwide. Despite the paucity of relevant research regarding the clinical practices for GISTs, a series of studies performed by Chinese physicians in the fields of recurrence risk classification, laparoscopic surgery, and adjuvant therapy have contributed to the diagnosis and treatment of GISTs. The lack of innovative drugs, slow approval of new drugs, and insufficient research funds have limited further advancements in GIST-related research in China. In recent years, increased investment in scientific research has allowed for these advancements to be made by creating conditions for Chinese physicians to conduct high-level clinical research. Chinese researchers hope to further shorten the gap between China and the rest of the world in the field of GIST research within a relatively short period. The purpose of the current review article was to present the most updated information regarding the diagnosis and treatment of GISTs in Chinese medical practice and to suggest prospective research in this field.

Risk stratification in GIST: shape quantification with CT is a predictive factor

Background

Tumor shape is strongly associated with some tumor’s genomic subtypes and patient outcomes. Our purpose is to find the relationship between risk stratification and the shape of GISTs.

Methods

A total of 101 patients with primary GISTs were confirmed by pathology and immunohistochemistry and underwent enhanced CT examination. All lesions’ pathologic sizes were 1 to 10 cm. Points A and B were the extremities of the longest diameter (LD) of the tumor and points C and D the extremities of the small axis, which was the longest diameter perpendicular to AB. The four angles of the quadrangle ABCD were measured and each angle named by its summit (A, B, C, D). For regular lesions, we took angles A and B as big angle (BiA) and small angle (SmA). For irregular lesions, we compared A/B ratio and D/C ratio and selected the larger ratio for analysis. The chi-square test, t test, ROC analysis, and hierarchical or binary logistic regression analysis were used to analyze the data.

Results

The BiA/SmA ratio was an independent predictor for risk level of GISTs (p = 0.019). With threshold of BiA at 90.5°, BiA/SmA ratio at 1.35 and LD at 6.15 cm, the sensitivities for high-risk GISTs were 82.4%, 85.3%, and 83.8%, respectively; the specificities were 87.1%, 71%, and 77.4%, respectively; and the AUCs were 0.852, 0.818, and 0.844, respectively. LD could not effectively distinguish between intermediate-risk and high-risk GISTs, but BiA could (p < 0.05). Shape and Ki-67 were independent predictors of the mitotic value (p = 0.036 and p < 0.001, respectively), and the accuracy was 87.8%.

Conclusions

Quantifying tumor shape has better predictive efficacy than LD in predicting the risk level and mitotic value of GISTs, especially for high-risk grading and mitotic value > 5/50HPF.

Key Points

• The BiA/SmA ratio was an independent predictor affecting the risk level of GISTs. LD could not effectively distinguish between intermediate-risk and high-risk GISTs, but BiA could.

• Shape and Ki-67 were independent predictors of the mitotic value.

• The method for quantifying the tumor shape has better predictive efficacy than LD in predicting the risk level and mitotic value of GISTs.

Gastrointestinal stromal tumor: epidemiology, diagnosis, and treatment

PURPOSE OF REVIEW

The purpose of this review is to review the past year's literature to provide comprehensive information to researchers, physicians, and the general public regarding the epidemiology, diagnosis, and treatment of gastrointestinal stromal tumors (GISTs). Common ground as well as divergent viewpoints will be highlighted and discussed.

RECENT FINDINGS

The diagnosis of GISTs may involve imaging tests such as computed tomorgraphy scan and MRI, endoscopy with or without endoscopic ultrasound, and biopsy. Only biopsy, however, can yield a positive diagnosis. As most GISTs express KIT protein, immunostaining for KIT and/or molecular genetic testing for mutations in KIT can diagnose 95% of GISTs. Regorafenib, a drug that inhibits various protein genes that lead to GIST development is a relatively new treatment modality.

SUMMARY

The current review should enable clinicians to best select the diagnostic and treatment approaches to GIST.

Chondroid gastrointestinal stromal tumor in the stomach with early adenocarcinoma

OBJECTIVE

To explore the pathologic features of gastric chondroid gastrointestinal stromal tumors.

METHODS

The clinicopathologic data of one case of gastric chondroid gastrointestinal stromal tumor were collected and the features were analyzed by literature review.

RESULTS

The male patient was 64 years old and had suffered from upper abdominal fullness discomfort without obvious cause for 5 years. Gastroscopic examination showed a rough area located in the lesser curvature of the gastric antrum, measuring 6 cm × 4 cm. CT scan showed the stomach wall was unevenly thick at the gastric antrum and stomach outlet. Multiple enlarged lymph nodes were seen nearby. The biopsy pathology showed adenocarcinoma of gastric antrum. The patient underwent laparoscopic gastrectomy and gastric chondroid gastrointestinal stromal tumor was found with adenocarcinoma of the stomach. Asp842Val mutation was found in the PDGFRα 18 exon.

CONCLUSION

Gastric chondroid gastrointestinal stromal tumors are rare and low risk. Tumor cells express CD117 and Asp842Val mutation in the PDGFRα 18 exon revealed by genetic sequencing suggesting this kind of tumor might be resistant to imatinib.

Establishment and Verification of Prognostic Nomograms for Patients with Gastrointestinal Stromal Tumors: A SEER-Based Study

With gastrointestinal tract as the origin, gastrointestinal stromal tumor (GIST) is recognized as the very widespread mesenchymal tumor. A precise prognostic model of survival is required to guide the treatment options of patients with GIST. This study was designed to map the overall survival (OS) and cancer-specific survival (CSS) of GIST patients. According to the Surveillance, Epidemiology, and End Results (SEER) program database, we acquired the data of 6,713 patients with GIST who were diagnosed between 2004 and 2014. We randomly separated the patients into training (n = 4,699) and validation (n = 2,014) groups. To assess the prognostic impact of multiple clinical parameters, the Kaplan-Meier approach and the Cox proportional hazards regression model were adopted, where essential prognostic variables were combined to create nomograms. The consistency index and curve of calibration had been adopted to assess nomogram discrimination ability and prediction accuracy. A multifactor analysis of the training cohort showed that age, gender, size of tumor, location, and primary surgery were remarkably related to survival, and these variables were applied to create nomograms. The nomogram demonstrated excellent accuracy in estimating 2-, 3-, and 5-year OS and CSS, with a C-index of 0.740 (95% confidence interval [CI], 0.723-0.757) for OS and 0.743 (95% CI, 0.718-0.768) for CSS. In the validation cohort, the nomogram-predicted C-index was 0.741 for OS (95%CI, 0.717-0.765) and 0.746 (95%CI, 0.713-0.779) for CSS. All calibration curves showed good consistency between predicted and actual survival. A new nomogram was created and verified to predict the OS and CSS of patients with GIST. These new prognostic models can help enhance the accuracy of survival outcome predictions, thus facilitating to provide constructive therapeutic suggestions.

A new nomogram for recurrence-free survival prediction of gastrointestinal stromal tumors: Comparison with current risk classification methods

BACKGROUND

This study aimed to build a new risk stratification nomogram for gastrointestinal stromal tumors (GISTs) focused on a popular factor Ki-67 to enable individualized and precise predictions of the most suitable candidates for imatinib therapy.

METHODS

We retrospectively collected clinicopathologic data of the patients diagnosed with GISTs from January 1998 to December 2015 at Southern Medical University Nanfang Hospital as the experiment group. And patients with GISTs at the Sun Yat-sen University Cancer Center from January 2007 to December 2012 were included as the validation group. The nomogram was built using Kaplan-Meier method and the Cox proportional hazards regression model. The receiver operating characteristic (ROC) curves were established to compare the discriminative ability of the new nomogram with other risk stratification systems, including the modified National Institute of Health (modified NIH) criteria, Armed Forces Institute of Pathology (AFIP) criteria, Memorial Sloan Kettering Cancer Center (MSKCC) prognostic nomogram, and contour maps.

RESULTS

In univariate analysis, the tumor size, site, mitotic count, tumor rupture and Ki-67 labeling index were significant factors (all P < 0.05) and included in the Cox model to build our nomogram. According to the ROC curve, our new nomogram showed the largest AUC value (0.778) compared with that of the other classification methods (contour maps, AUC = 0.743; AFIP, AUC = 0.719; MSKCC, AUC = 0.712; and modified NIH, AUC = 0.719).

CONCLUSION

Our new nomogram exhibits an excellent performance and might become a potential risk stratification to support therapeutic decision-making for GISTs.

Standard Approach to Gastrointestinal Stromal Tumors - Differences between China and Europe

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. With the considerable research and application of molecular-targeted therapy for GISTs in the last two decades, GISTs have become a model of multidisciplinary oncological treatment. Although Western clinical guidelines are available for GISTs, such as those by the European Society of Medical Oncology (ESMO), the clinical situations in China are different from those in European countries. There are distinct differences between the clinical practice, diagnostic methods, surgical approach, and availability of new targeted agents in China and those in Europe. This review summarizes the Chinese GIST consensus guidelines compared to the European ones, which may provide an optimal approach to the diagnosis and management of GIST patients.