Computed tomography in the size measurement of gastric gastrointestinal stromal tumors: Implication to risk stratification and "wait-and-see" tactics

Association between calcification and risk stratification in gastric gastrointestinal stromal tumors

BACKGROUND

Risk assessment of gastric gastrointestinal stromal tumors (GISTs), particularly those with a diameter ≤ 5 cm, remains a clinical challenge. Previous research has primarily focused on tumor size, ulceration, necrosis, and enhancement patterns, with less emphasis on the role of tumor calcification, which remains controversial regarding its correlation with malignancy risk.

OBJECTIVE

This study aims to explore the characteristics of calcification in gastric GISTs and its correlation with risk stratification as defined by the National Institutes of Health (NIH), to improve preoperative risk assessment for gastric GISTs ≤ 5 cm.

METHODS

A retrospective analysis of 385 pathologically confirmed gastric GIST patients, including 178 with small gastric GISTs (< 2 cm), was conducted. Tumors were categorized into low-risk (very low / low) and high-risk (intermediate / high) groups based on NIH criteria. Variables such as age, gender, tumor long-axis diameter, calcification rates, calcification size, the number and distribution of calcification, calcification to tumor long-axis diameter ratio were analyzed. Logistic regression was used to identify independent predictors of malignancy for gastric GISTs, with predictive values assessed via receiver operating characteristic (ROC) curves.

RESULTS

Significant differences were found between high-risk and low-risk groups in treatment methods, tumor long-axis diameter, the ratio of calcification to tumor long-axis, and calcification distribution (P < 0.05). Calcification rates varied across risk categories, with 23.6% in very low-risk, 31.6% in low-risk, 9.8% in intermediate-risk, and 31.7% in high-risk categories (P < 0.05). In GISTs ≤ 5 cm, both tumor long-axis diameter (OR = 3.07, 95% CI: 2.29-4.10) and calcification (OR = 0.36, 95% CI: 0.13-0.97) were independent predictors of malignancy risk (both P < 0.05). ROC curve analysis yielded areas of 0.849 for tumor long-axis diameter, 0.578 for calcification, and 0.862 for their combination.

CONCLUSION

The study indicates lower calcification rates in intermediate-risk gastric GISTs and higher rates in other risk categories. Additionally, tumors of different sizes exhibit two distinct calcification patterns, suggesting possible differing mechanisms of calcification in tumors. Calcification in gastric GISTs ≤ 5 cm acts as a protective factor against higher malignancy risk, and when combined with tumor long-axis diameter, significantly enhances predictive accuracy over long-axis diameter alone.

The maximum transverse diameter: an effective indicator for predicting peroral en bloc retrieval rate of mesenchymal tumors after endoscopic resection

BACKGROUND

Gastrointestinal mesenchymal tumors (GIMTs) are being increasingly resected under endoscopy. Large GIMTs cannot be completely retrieved through the mouth, but the cut-off diameter of peroral en bloc retrieval (PEBR) for GIMTs completely resected is still unknown. This study aimed to investigate the ability of maximum transverse diameter (MTD) to predict the PEBR rate of GIMTs after endoscopic resection (ER).

METHODS

We retrospectively reviewed all patients who underwent ER for upper GIMTs from January 2009 to August 2023. The MTD was measured according to the maximum transverse diameter of specimen immediately retrieved after ER. For the PEBR rate, the independent predictors and optimal cut-off value of MTD were determined by logistic regression analysis and the receiver operating characteristic (ROC) curve analysis. The potential significance of preoperative CT for the evaluation of MTD was also clarified.

RESULTS

A total of 2032 patients were diagnosed with upper GIMTs after en bloc resection under endoscopy. The overall PEBR rate was 98.72% (2006/2032). The PEBR rate was 100% for 1943 GIMTs with MTD < 2.5 cm, 85.71% (60/70) for GIMTs with 2.5 cm but ≤ 3.0 cm, and 15.79% (3/19) for GIMTs with MTD > 3.0 cm, and these rates were significantly different (P < 0.01). In terms of the PEBR rate of GIMTs, the ROC curve revealed that the optimal cut-off MTD value was 3.0 cm, and logistic regression analysis revealed that MTD > 3.0 cm was an independent predictive factor (OR 71.07, 95% CI 9.14-552.43; P < 0.001). The MTD of CT was related to that of the resected specimen (r = 0.7149, P < 0.01), and CT underestimated the mean MTD of upper GIMTs by 0.17 cm (95% CI 0.09-0.24, P < 0.01).

CONCLUSION

MTD is an effective indicator for predicting the PEBR rate of GIMTs after ER. Resected specimens with MTD > 3.0 cm could not be routinely retrieved en bloc. Preoperative CT is suitable for evaluating the MTD of GIMTs, but underestimates the mean MTD of upper GIMTs by 0.17 cm.

Prediction of Ki-67 expression and malignant potential in gastrointestinal stromal tumors: novel models based on CE-CT and serological indicators

PURPOSE

To identify more reliable imaging and serological indicators for predicting Ki-67 expression and malignant potential in gastrointestinal stromal tumors, as well as to develop a preoperative prediction model with clinical utility.

PATIENTS AND METHODS

This study retrospectively analyzed patients with gastrointestinal stromal tumors (GIST) diagnosed at the First Affiliated Hospital of Jinzhou Medical University between May 2018 and May 2024. Univariate logistic analyses, two-way stepwise regression, P-value stepwise regression, and LASSO regression were employed to screen for Ki-67 high expression and high malignant potential risk factors associated with GIST. Models were established using various regression methods; Nomograms, calibration curves, and clinical decision curves were generated for the two best prediction models.

RESULTS

Two-way stepwise regression analysis revealed that diameter (P=0.037; OR=1.22; 95% CI: 1.01 - 1.46), growth pattern (extraluminal type: P=0.028; OR=3.54; 95% CI: 1.14 - 10.94), enhancement model (P=0.099; OR=0.39; 95% CI: 0.12 - 1.20), EVFDM (P=0.069; OR=0.43; 95% CI: 0.17 - 1.07), PLR (P=0.099; OR=3.06; 95% CI: 0.81 - 11.59), and OPNI (P=0.058; OR=2.38; 95% CI: 0.97 - 5.84) are identified as independent risk factors for Ki-67 expression. Utilizing the two-way stepwise regression model to predict Ki-67 expression, the area under the curve (AUC) for the training group was 0.865 (95% CI: 0.807-0.922), while for the validation group it was 0.784 (95% CI: 0.631-0.937). The Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) for the training group were 153.360 and 174.619, respectively. Two-way stepwise regression analysis revealed that volume (P < .001, OR = 1.06; 95% CI: 1.03 - 1.09), contour (P = 0.066; OR = 0.17; 95% CI: 0.05 - 0.62), ulcer (P = 0.094; OR = 0.16; 95% CI: 0.03 - 0.98), IBSC (P = 0.008; OR = 5.27; 95% CI: 1.57 - 17.69), and OPNI (P = 0.045; OR = 0.22; 95% CI: 0.05 - 0.96) are independent risk factors for malignant potential. Utilizing the two-way stepwise regression model to predict malignant potential, the AUC for the training group was 0.950 (95% CI: 0.920 - 0.980), while for the validation group it was 0.936 (95% CI: 0.867 - 1.000). The AIC and BIC values for the training group were 96.330 and 114.552, respectively.

CONCLUSION

Diameter, growth pattern, enhancement pattern, EVFDM, PLR, and OPNI are independent risk factors for GIST with high Ki-67 expression. Additionally, volume, contour, ulceration, IBSC, and OPNI serve as independent risk factors for GIST with high malignant potential. The preoperative models developed using CT images can predict the malignant potential and Ki-67 expression status of GIST to a certain extent. When combined with serological indicators, these models' predictive performance can be further enhanced.

Pathologic complete response to neoadjuvant imatinib of a gastric stromal tumor with concomitant mutations in KIT: A case report and literature review

Key clinical message

We report the first case of pathologic complete response (pCR) to neoadjuvant imatinib in a gastric stromal tumor harboring KIT mutations in both exons 11 and 9. The significance of this co-occurrence is unknown and might increase the responsiveness of gastrointestinal stromal tumors (GISTs) to imatinib.

Abstract

pCR of GIST to neoadjuvant imatinib is rare. We report a case of pCR to neoadjuvant imatinib in a gastric stromal tumor that harbored co-occurrence of multiple KIT mutations in exons 11 and 9. This co-occurrence in exons 9 and 11 is the first to be reported in the English literature.

Mesenchymal tumors of the stomach: radiologic and pathologic correlation

Mesenchymal tumors of the stomach are uncommon, with gastrointestinal stromal tumor (GIST) being the most common among them. Majority of the tumors may arise from cells of Cajal, smooth muscle cells, neural cells, totipotent stem cells, adipocytes or fibroblasts. Imaging plays an important role not only in staging but also in characterizing these tumors. Many of these tumors have characteristic imaging features. GISTs usually present as large cavitating and necrotic tumors with exophytic component. Presence of fat tissue within the tumor suggests a lipoma or a teratoma, early phase hyperenhancement indicates glomus tumor and hemangioma, and delayed contrast enhancement is seen in schwannoma. Their differentiation from epithelial tumors like carcinoma and neuroendocrine tumors is often possible based on the location (mesenchymal tumors are intramural), spread, morphological appearance and enhancement patterns. However, overlapping features exist between these tumors with imaging often being only suggestive. A biopsy is necessary for a definitive diagnosis in many cases.