111P Oncologic outcomes of the pelvic bone tumors

Primary bone sarcomas of the pelvis represent the most challenging problem in limb-saving surgery. Chondrosarcoma is the most common type, followed by osteosarcoma and Ewing's sarcoma. We propose to study a group of patients with primary bone sarcoma of the pelvis treated with limb salvage surgery and analyze overall survival, local recurrence rates and functional outcomes. A retrospective review was performed, and all patients diagnosed with pelvic primary bone sarcomas at a specialized oncology centre in the Republic of Uzbekistan between 2017 and 2022 were analyzed. Patients treated with limb salvage surgery and with a minimum of 12-month follow-up for patients alive were included. The overall survival and the local recurrence rate were calculated for the assessment of oncological results. The associations with gender, age, histological grade, type of surgery, margins chemotherapy response and use of navigation were examined. Thirty-two patients were included in the study. The mean age was 37 years (range 16-58), and mean follow-up was 34 months (range 6-129). Among the tumor lesions on the first place patients with chondrosarcoma - 18 (56,25%), Ewing's sarcoma - 2 (6,25%), osteosarcoma - 8 (25%), GCT - in 4 (12,5%). Four (12.5%) tumors were histologically classified as high-grade sarcomas, four (12.5 %) as low-grade sarcomas and three (75 %) as dedifferentiated sarcomas. Cancer-specific overall survival was 37.5 % for 5 years and 31 % for 10 years. Local recurrence rate was 30 %. High-grade tumors and chemotherapy necrosis below 90 % were negative prognosis factor. Postoperative complication rate was 34.5 % (n:11), being deep infection the most prevalent (n:3). Reconstruction of the pelvis after an oncology resection for primary pelvic sarcomas increased the incidence of complication significantly (p < 0.001). Patients with low grade pelvic sarcomas have a good prognosis after pelvic resection, but those with high grade sarcomas continue to have a poor prognosis. Independent prognostic factors are few; an adequate surgical margin is critical to prevent local recurrence, and the surgical stage is related to the risk of distant metastasis.