Quality of Surgery and Outcome in Localized Gastrointestinal Stromal Tumors Treated Within an International...

Area of Science:

• Oncology
• Surgical Oncology
• Gastroenterology

Background:

• The impact of surgical margin quality on survival in localized gastrointestinal stromal tumors (GIST) requires further clarification.
• Microscopic positive margins (R1 resection) may affect patient outcomes, but the role of adjuvant therapy in this context is not fully understood.

Purpose of the Study:

• To evaluate the association between microscopic surgical margins (R0 vs. R1) and overall survival (OS) in patients with localized GIST.
• To assess the influence of adjuvant imatinib treatment on OS in relation to R1 resection status.

Main Methods:

• A post hoc analysis of a randomized phase III trial involving 908 patients with localized GIST.
• Patients were randomized to receive 2-year adjuvant imatinib or no adjuvant treatment after surgery.
• Overall survival was estimated using Kaplan-Meier and compared between R0/R1 groups using Cox models, with stratification for key factors. Tumor rupture was analyzed separately.

Main Results:

• A total of 908 patients were included, with 17.8% having R1 resections. Overall survival was significantly worse for patients with R1 resections (HR, 2.05).
• The association between R1 resection and worse OS was observed both with (HR, 2.65) and without (HR, 1.86) adjuvant imatinib.
• When tumor rupture was excluded from the R1 category, the significant difference in OS between R1 and R0 resections disappeared (HR, 1.05).

Conclusions:

• The negative impact of R1 resection on overall survival in localized GIST is primarily associated with the presence of tumor rupture.
• Microscopic positive margins (R1) alone, without tumor rupture, do not appear to significantly worsen overall survival in patients treated with or without adjuvant imatinib.