Pattern of recurrence in patients with ruptured primary gastrointestinal stromal tumor (GIST).

Abstract

10053 Background: It is often recommended to regard patients with a ruptured of GIST as having a very high risk for recurrence. Patients have been entered to phase III adjuvant trials of imatinib. However there are only case reports and a series on abdominal leiomyosarcoma available with real data. Methods: 554 pts. with histologically confirmed GIST were retrieved from our database. The written reports from surgical resection were reviewed in detail for circumstances of emergency, intraoperative findings, handling of the specimen, signs of tumor rupture, margins of clearance, and concordance with the pathology report. Review pathology and mutation analysis in genes encoding KIT and platelet-derived growth factor alpha (PDGFRA) was done in 61%. Median follow-up is 52 months. Results: We identified 27pts (17 f, 10 m; median age 51, range 26-69 yrs) with a documented tumor rupture: n=19 with spontaneous tumor perforation indicating laparotomy, n=2 with a ruptured tumor detected incidentally during operation for intra-abdominal hemorrhage after trauma, n=6 with rupture of the specimen during resection. Primary tumor location: stomach n=7, duodenum n=1, small bowel n=19. Median tumor size was 10.5 cm (range, 4-28 cm). According to the Miettinen & Lasota system the distribution of very low : low : intermediate : high risk tumors was 1:2:7:17. Of the 23 pts. without metastases at presentation, 18 remained untreated and all but one developed tumor recurrence. Median time to relapse (RFS) was 22 months (range, 5-83+ months, 95% CI: 8.5-35.4 mos). One patient remains free from disease at 83+ mos. The single most often detected mutation involved codon 557-558 in 11/24 pts: W557_558Kdel (n=5), other mutation types n=6. The RFS of this subgroup was 11 mos. vs. 26 mos. with mutations at other exons of KIT, PDGFRA or wt. Conclusions: Patients with a perforation or rupture of a GIST to the abdominal cavity have a close to 100% risk of tumor recurrence. Patients with deletion mutation of codons 557-558 show a less than 1 year RFS. This group of patients are clear candidates for adjunctive drug therapy even if size and mitotic count of the primary tumor would not make them eligible according to risk classification systems. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Novartis, Pfizer Novartis, Pfizer Novartis Novartis