1511P - Surgery in the treatment of metastatic and recurrent Gastrointestinal Stromal Tumors

Abstract

Background: Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal tumors of the gastrointestinal tract. Surgery is the method of choice in treatment of localized GISTs but it also plays a great role in the treatment of advanced forms. The main goal of our study is to define the role of surgery for locally advanced and metastatic/recurrent lesions. Methods: We have performed a retrospective analysis from a prospectively documented database. All histologically proven GISTs, diagnosed and treated between 2003 and 2016, were enrolled from 4 clinics in Saint-Petersburg, Russia. Cases of recurrent or metastatic GISTs were selected from the registry, and baseline characteristics and survival outcomes were analyzed. Patients were classified into two groups. The surgical treatment group (ST group) included those who underwent surgical treatment in addition to tyrosine kinase inhibitor (TKI) therapy after recurrence or metastasis, whereas the drug treatment group (DT group) included those who were treated only with TKI therapy. Results: Metastasis or recurrence developed in 34 (22,8%) of the 149 patients with GISTs who had undergone surgery for primary localized or locally advanced tumors, 13 (38,2%) of whom were assigned to the ST group and 21 (61,8%) to the DT group. Median follow-up was 68 (4-162) months. In the ST group the 3-year overall survival rate (OS) was significantly higher than in DT group (92,3 vs. 61,9%, p < 0,05) but these groups didn't differ with respect to the 5-year overall survival rate (61,5 vs. 52,4%, p > 0,05). Median time to progression (TTP) was 23,9 months in the DT group and 29,7 months in the ST group (p > 0,05). OS was correlated with the pattern of recurrence: local-regional recurrence vs. distant metastasis – 3-year OS (94,4 vs. 50%, p < 0,05), 5-year OS (77,8 vs. 31,25%, p < 0,05). Median TTP didn't differ in both groups (18,5 vs. 20 months, p > 0,05). Conclusions: Continuous TKI therapy appears to be important primarily for the prognostic improvement of patients with recurrent/metastatic GISTs. Surgical resection may have benefits when combined with TKI therapy for patients with stable disease or disease responsive to TKI therapy especially in the cases of local-regional recurrence. Legal entity responsible for the study: Orlova Rashida Funding: None Disclosure: All authors have declared no conflicts of interest.