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

Abstract

Introduction: This study aimed to compare the radiologic size of gastric gastrointestinal stromal tumors (GISTs) on computed tomography (CT) with the pathologic size in a Chinese population, and elucidate the potential significance of the CT size in the preoperative risk stratification. Materials and methods: The study enrolled 314 patients treated by endoscopic/surgical resection of gastric lesions that proved postoperatively to be GISTs. Bland-Altman analysis and intraclass correlation coefficient (ICC) were adopted to assess the size agreement between CT and pathology. Independent predictors of risk category underestimation and the optimal cut-off value of CT size were determined by logistic regression analysis and the receiver operating characteristic (ROC) curve. Results: CT underestimated gastric GISTs size by 0.30 cm [95% confidence interval (CI): (À0.42, -0.19); p < 0.001]. In the subgroup analysis, the size underestimation was 0.10 cm in GISTs 5 cm [95% CI: (À0.19, À0.01); p ¼ 0.024]; and 0.75 cm in GISTs >5 cm [95% CI: (À1.05, 0.45), p < 0.001]. Though ICC values showed well reliability for the corresponding pathologic size, with 0.95 in all size, 0.86 in size 5 cm, and 0.92 in size >5 cm respectively. Risk underestimation by CT imaging mainly occurred in gastric GISTs with smaller size ( 5 cm; p ¼ 0.010) and lower mitotic index ( 5 per 50 high-power fields; p ¼ 0.011). CT size of 3.65 cm was defined as an absolute cut-off to differentiate intermediate/ high-risk patients from low-risk group, with 87.5% sensitivity at a specificity of 57.8%. Conclusion: Preoperative CT underestimated the mean size by 0.30 cm in gastric GISTs. A CT size of 3.65 cm would facilitate the selection of potential intermediate/high-risk patients, instant intervention should be encouraged in the absence of contraindications.

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

“…Nevertheless, watch and wait could be an option in particular cases such as elderly with co-morbidities, strong wishes for "wait-andsee", or in long surgery waiting lists. 37 Imatinib-sensitive biomarkers of GISTs: KIT expression (CD117), KIT mutations in exons 9 and 11, PDGFRA mutations in exons 12 and 18. However, resistance biomarkers are BRAF mutation, 38 secondary mutation in the ATP binding domain or the activation-loop domain of KIT (exon 13 and 14 and rarely 17), 39 or codon 842 in exon 18 of PDGFRA, over expression of KIT in Neurofibromatosis Type 1 associated GIST cells and loss of KIT expression 6 accompanied by activation of alternative pathways.…”

“…Surgery remains the standard of care in resectable forms. Nevertheless, watch and wait could be an option in particular cases such as elderly with co‐morbidities, strong wishes for “wait‐and‐see”, or in long surgery waiting lists 37 …”