Retroperitoneal Extragastrointestinal Stromal Tumors Have a Poor Survival Outcome: A Multicenter Observational Study

Area of Science:

• Oncology
• Gastroenterology
• Pathology

Background:

• Gastrointestinal stromal tumors (GISTs) typically originate in the GI tract.
• Extra-GISTs (eGISTs) are rare lesions resembling GISTs but found outside the GI tract.
• Prognostic factors and survival outcomes for eGISTs, particularly in Asian populations, require further elucidation.

Purpose of the Study:

• To identify risk factors for eGISTs.
• To assess the association of eGISTs with overall survival (OS) and disease-free survival (DFS).

Main Methods:

• Retrospective analysis of 55 surgically treated eGIST cases from four hospitals (2006-2017).
• Exclusion criteria included evidence of other primary lesions or adhesion to the GI serosa.
• Immunohistochemical, genetic testing, and staging using National Institutes of Health (NIH) criteria were performed.

Main Results:

• eGISTs commonly occurred in the retroperitoneum (36.4%) and were frequently high-risk (85.5%).
• KIT 11 mutations were most common (76.5%), with 25% wild-type.
• Retroperitoneal tumors and tumors >15 cm were independently associated with significantly poorer OS and DFS.

Conclusions:

• eGISTs are predominantly high-risk tumors, frequently located in the retroperitoneum.
• Tumor location (retroperitoneum) and size (>15 cm) are critical prognostic indicators for eGISTs.
• These findings highlight key factors influencing survival in patients with eGISTs.