Prognostic factors in High-Grade Localized Osteosarcoma of the Extremities: The Tunisian Experience.

Background: Osteosarcoma is the most frequent bone cancer occurring in children and adolescents aged 10-20 years. Several prognostic factors have been identified by studies done at western centers. The aim of our study was to identify the prognostic factors in Tunisian patients in order to improve their management.

Methods: We reviewed the data of localized limb osteosarcoma patients treated in Salah Azaïz Institute from January 1980 to December 2018. Patient's treatment and survival variables were assessed. Patients received a neoadjuvant chemotherapy and underwent surgery in an expert center. They received afterward an adjuvant chemotherapy depending on the tumor necrosis assessed by Huvos.

Results: Eighty-five patients were enrolled. Mean duration of follow-up was 30 months (range 1-297 months). Males were 1.6 times more frequent, median age was 17 (from 1 to 62 years). Conventional osteoblastic osteosarcoma was the most frequent histological subtype (77%). Median tumor size was 10 cm. Femoral location was the most frequent (60%). The overall average history of symptoms was 103 days (4 to 423 days). The 5-year overall-survival was 38% and the event free survival 32%. Tumor site, lactate dehydrogenase levels, high methotrexate levels at 24 h, clinical evaluation of the tumor perimeter, surgery type and delay of relapse were found to affect overall survival. Tumor site, Lactate dehydrogenase levels and clinical evaluation of the tumor perimeter affected the progression free survival.

Conclusion: Demographic characteristics of Tunisian patients are mainly the same than worldwide. Femoral site, normal level of lactate dehydrogenase, a clinical response during neoadjuvant treatment, an R0 surgery, a delay of relapse over 2 years and Median H24 Methotrexate level superior to 4.4 µmol/l were associated with a better prognosis in our study.