Abstract 4706: Wide surgical margins are of prognostic importance in GIST.

Abstract

Abstract Background: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumor of the gastrointestinal tract and even in the era with molecularly targeted agents is surgery the mainstay of treatment and the only treatment that could lead to cure. Microscopically negative margins are today accepted as sufficient margins for cure while tumor rupture is known to result in poor prognosis and therefore taken into account in prognostic models. In other types of soft tissue sarcoma has wide margins been known to be of importance for recurrence while this has not been shown in GIST. Methods: 116 patient were included in the study, 55 male and 61 female, mean age 61 years (10-86) and mean follow-up 73 month (4,6-365) that has been evaluated for surgical margins at the time for surgery or at referral to our institution. The criteria used has been those used for sarcoma in other locations were “Wide margins” are defined as 3 cm marginal in the organ of origin combined with an completely intact peritoneal surface covering the tumor. In cases where the tumor is stucked to surrounding tissue or organ, that part has been resected “un bloc” with the tumor. “Marginal margins” are defined as R0 resection with less then 3 cm and “Intralesional margin” is when the tumor is shelled out or damage to surrounding peritoneal surface or judged as R1 resection. Local recurrence has been defined as recurrence at site of origin or intraabdominal recurrence of tumor in the peritoneum and metastatic disease when recurrence is distant metastasis. Results: We found 48 cases with wide margins(3 recurrence), 39 with marginal margins (15 recurrence) and 29 with intralesional margins (17 recurrence). There was significant difference calculated as Kaplan-Meier for both local recurrence (p=0,00016), distant metastasis (p= 0,004) and survival (p= 0,0047) and in cox regression analysis hazard ratio were 7,4 for marginal margins and 8,08 for intralesional margins compared to wide margins and this was not correlated with size or site (p= 0,007). Conclusion: Surgical margins is of great importance in GIST both for local recurrence, distant metastasis and survival and patient with GIST should be operated with wide margins, in accordance with principals of other sarcoma. Citation Format: Jan Ahlen, Robert Branstrom, Inga-Lena Nilsson. Wide surgical margins are of prognostic importance in GIST. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4706. doi:10.1158/1538-7445.AM2013-4706