[Synchronous multicentric osteosarcoma: treatment and prognostic factor analysis].

To identify the clinical outcome and prognostic factors of synchronous multicentric osteosarcoma (SMOS). The clinical data of 2 602 conventional osteosarcoma patients admitted to Beijing Jishuitan Hospital from January 1995 to June 2018 were retrospectively analyzed. Finally, 56 (2.1%) cases were confirmed as SMOS according to clinical and imaging database, medical record and pathological results.All epidemiological data of SMOS cases,initial diagnosis time, tumor site, number of lesions, chemotherapy, surgical treatment, alkline phosphatase (AKP),lactate dehydrogenase (LDH) and oncological results were collected in our institution. The Survival rate, comparison of various parameters, univariate analysis and multivariate Cox regression were performed with statistical software. There were 41 males and 15 females enrolled in this research, the median and mean ages were 15 and 18 years (range, 8-50 years) respectively. All of them were multi-site involved, whereas the initial complaints of sites distribution were 32 cases of femur, 13 cases of tibia, 4 cases of humerus, 3 cases of fibula, 2 cases of spine, 1 case of sternum and 1 case of calcaneus. Forty-four of 56 cases performed adjuvant chemotherapy and 31 of them underwent surgical treatment. The mean follow-up time was 15.4 (range, 1-186) months. Thirty-five cases died of disease at the end of the follow-up. The 5-year survival rate was 10.4%. According to the number of lesions stratification, the 2-year survival rates in patients with low (<5 sites) and high (≥5 sites) tumor load was 33.6% and 0, respectively (χ(2)=6.697, 0.010). The 2-year survival rate of chemotherapy and non-chemotherapy patients was 20.8% and 0, respectively (χ(2)=6.998, 0.008), the value of AKP after chemotherapy(median: 272 IU/L) significantly decreased when compared with that at the initial diagnosis (median: 454 U/L) (-3.274, 0.001).The 2-year survival rate in patients with and without standard chemotherapy was 55.6% and 0, respectively (χ(2)=8.798, 0.003). The 2-year survival rate was 25.0% in the surgical group and 0 in the non-surgical group, respectively (χ(2)=7.942, 0.005). Multivariate cox regression analysis with the forward Wald method indicated that standard chemotherapy was the only variable contributor to survival and prognosis of multifocal osteosarcoma. SMOS has low survival rate and poor prognosis. Chemotherapy and surgery can improve the survival rate, standard chemotherapy is an independent prognostic factor.