An analysis of extraskeletal osteosarcoma based on the literature.

Extraskeletal osteosarcoma (ESOS) is a very rare malignant tumor. This study aimed to provide more evidence about the natural history and clinical features of ESOS, and clarify the impact of chemotherapy (CT) and radiotherapy (RT) on patient survival and postoperative recurrence for the sake of gaining a better understanding about the disease. Patient/tumor characteristics, recurrence, treatment, and follow-up durations were collected by searching studies in PubMed, Web of Science, Ovid, Elsevier, SpringerLink, Chinese National Knowledge Infrastructure (CNKI), and WAN FANG Data before June 30, 2023. Data were analyzed by SPSS-26. Altogether 1287 patients diagnosed with ESOS were retrieved from the literature. Of them, follow-up data were available in 981 patients, in whom 78 patients (7.6%) had metastases and 730 patients (74.5%) had localized disease at the time of diagnosis. Of the 730 patients with localized disease, 682 (93.4%) received surgical resection. The 5-year OS in all 981 patients, 78 metastatic patients, and 682 patients with localized disease was 33.40%, 4.9% and 41.1%, respectively. Of the 682 surgical patients, 367 patients underwent surgical resection alone, 170 received surgical resection + CT, 82 patients received surgical resection + RT, and 58 patients received both adjuvants. In addition, 348 (51%) of the 682 patients developed recurrence, including local recurrence (n = 102), metastasis (n = 130), and both (n = 116). Univariate analysis of 5-year PFS and 5-year OS showed that age, tumor size, CT, metastasis, and local recurrence were significant prognostic factors in the 682 patients with localized disease. There was no significant difference in 5-year OS between osteosarcoma-type and soft tissue-type regimens (P = 0.273). Multivariate analysis of 431 patients showed that postoperative recurrence and metastasis were significant prognostic factors for survival, and CT was not a significant prognostic factor, though CT decreased the incidence of local recurrence in ≤ 45-year age group (P = 0.047). RT reduced the incidence of local recurrence in patients ≤ 45years (P = 0.035) and patients with tumors > 5 cm (P = 0.044). So, we recommend that CT should be used for patients aged ≤ 45years, and RT can be used for patients ≤ 45years or those with tumors > 5 cm for the sake of decreasing the incidence of local recurrence, which we believe would indirectly benefit the survival of ESOS patients.