Solitary fibrous tumor: A Brazilian cohort analysis.

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11068 Background: Solitary fibrous tumor (SFT) is a rare mesenchymal tumor that account for less than 2% of all soft tissue sarcomas. SFT has been identified in multiple anatomic locations and can arise anywhere in the body. Surgical management is the mainstay of treatment for localized disease. However, about 20% will develop locoregional recurrences or distant metastasis with a role for systemic treatment. Methods: A retrospective analysis was carried out in a large cancer center in Brazil. Our primary objective was to evaluate clinical and treatment aspects of metastatic/ locally advanced (Mtx/LA) SFT cohort and secondary to describe clinical characteristics of entire population diagnosed with SFT. Descriptive statistics was used for main results. Survival curves were estimated using Kaplan-Meier. Data were retrieved from electronic patient medical records. Results: From April, 1971 to October, 2017, 82 patients with SFT were treated. Median follow-up was 45.5 months. 67 (81.7%) were alive on the cut-off date. Median age at diagnosis was 51 (14-78). 40.2% men. Most common primary sites (PS) were pleura (19.8%), central nervous system (CNS - 11%) and pelvis (11%). 18 (21.9%) underwent chemotherapy for Mtx/LA disease. In this subgroup, 61.1% were men; PS retroperitoneal (22.2%), extremities (16.7%), CNS (16.7%). 66.7% had pulmonary, 44.4% hepatic, 27.8% bone metastasis and one (5.5%) local recurrence. All patients had at least one adverse prognostic factor (tumor size ≥ 10cm, positive margins, necrosis, ≥ 4/10 mitosis). One (5,5%) had Doege-Potter syndrome. 7 (38.9%) did one, 5 (27.8%) two and 6 (33.3%) ≥ 3 lines of treatment. First line was temozolomide/bevacizumab (TMZ/Bev) in 55.6%, followed by chemotherapy (Ch) in 27.8% and tyrosine kinase inhibitors (TKI) in 16.7%. Median progression-free survival was 3.5 months (95% IC: 0.0-7.4) and overall survival 27.3 months (95% IC: 18.7-36.0). Response rate using RECIST criteria was 12.5% for TMZ/Bev and 62.5% had stable disease. TKI and Ch had no response. Conclusions: SFT is rare and with heterogeneous clinical presentation. In our analysis, patients received a wide range of therapy, reflecting the lack of well-established systemic treatment option. TMZ/Bev showed consistent activity in Mtx/LA scenario.