Domestic research on extra-gastrointestinal stromal tumors: A ten-year review

There is currently no consensus on whether extra-gastrointestinal stromal tumors (EGISTs) and gastrointestinal stromal tumors (GISTs) are the same type of tumor, and whether the diagnosis and treatment of EGISTs can directly replicate the current diagnostic and treatment standards for GISTs. This study aims to further elucidate the clinical and pathological characteristics, diagnosis, treatment, and prognosis of EGISTs by analyzing the research results of domestic scholars in the field of EGISTs in the past decade.

A review was conducted on original Chinese and English research articles published from 2013 to 2022 focusing on EGISTs. A descriptive approach was used to extract key information from the literature, including patient demographics, tumor location, tumor diameter, mitotic figures, risk stratification, immunohistochemical markers, cell type, and prognostic factors. The data were subjected to statistical analysis.

A total of 12 articles containing 780 EGIST patients were included. The male-to-female incidence of EGISTs was 0.92꞉1. The most common sites of EGISTs were mesentery (30.96%), peritoneum or retroperitoneum (28.53%), omentum (20.32%), and pelvic cavity (12.52%). 52.77% of EGISTs had tumor diameters greater than 10 cm, and the proportions of EGISTs with nuclear fission patterns greater than 5/50 high power field (HPF) and greater than 10/50 HPF were 51.24% and 26.11%, respectively. The proportion of high-risk EGISTs was 79.05%. The positive rates of immune markers CD117, CD34, and DOG-1 in EGISTs were 82.3%, 69.0%, and 79.5%, respectively. The proportion of Ki-67 >5% was 49.2%, and the proportion of Ki-67 >10% was 24.8%. The proportions of EGISTs in spindle cells, epithelial cells, and mixed cells were 74.4%, 14.8%, and 13.1%, respectively. The diameter of the tumor, resection method, risk level, Ki-67 index, mitotic counts, presence of rupture/bleeding/necrosis/peripheral tissue invasion/recurrence and metastasis, as well as the use of imatinib treatment after surgery were important factors affecting the prognosis of EGISTs.

Current medical research is relatively well cognizant of GISTs with primary sites in the gastrointestinal tract. Compared with GISTs, EGISTs have large tumor diameters, high mitotic counts, a high percentage of high-risk grades, relatively unique molecular expression, and high aggressiveness. EGISTs differ from GISTs in clinicopathological characteristics. Whether EGISTs and GISTs share a common origin remains unclear. If they are distinct tumor entities, separate diagnostic and treatment guidelines for EGISTs should be established. If EGISTs are ultimately confirmed to be a special subtype of GISTs, then directly applying existing GIST-based standards to EGISTs may be inappropriate. A more scientific approach would involve subclassifying EGISTs based on anatomical location and then tailoring treatment strategies accordingly with reference to GIST guidelines.