Survival Differences of Patients with Resected Extraskeletal Osteosarcoma Receiving Two Different (Neo)Adjuvant Chemotherapy Regimens: A Systematic Review and Meta-analysis

Aims: Extraskeletal osteosarcoma (ESOS) is a malignant tumour developing in soft tissues, characterised by the production of osteoid or bone matrix by tumour cells. The standard treatment for localised ESOS is wide resection. Radiotherapy and chemotherapy are usually incorporated into the management of patients. Two types of chemotherapy regimen are mostly used: an osteosarcoma-type chemotherapy, based on cisplatin, and a soft-tissue sarcoma (STS)-type chemotherapy, using the combination of doxorubicin and ifosfamide. To investigate the difference in survival between these two chemotherapy regimens, a systematic review of studies reporting the 5-year disease-free survival (DFS) rates among patients with ESOS submitted to surgery and who received (neo)adjuvant chemotherapy with osteosarcoma-type or STS-type chemotherapy was carried out.

Materials and methods: Of the 401 articles identified by systematically searching the PubMed, Embase and Cochrane Central Register of Controlled Trials databases, six retrospective studies were included in the final analysis. In total, 319 patients with localised/resected ESOS were included in the study.

Results: Our meta-analysis showed a benefit in 5-year DFS favouring the use of osteosarcoma-type chemotherapy (relative risk = 1.32, 95% confidence interval 1.03-1.69; P = 0.54); I² heterogeneity was 0%. The 5-year DFS rate was 56.3% (95% confidence interval 48.3-64.3) with osteosarcoma-type chemotherapy and 45.2% (95% confidence interval 34.5-55.9) with STS-type chemotherapy, with I² heterogeneity of 27% and 0%, respectively.

Conclusions: Our analysis suggests that there may be a difference regarding the type of (neo)adjuvant chemotherapy regimen used in the treatment of patients with resected ESOS in favour of osteosarcoma-type chemotherapy. Future studies evaluating the role of this treatment modality in this scenario need to consider the type of chemotherapy regimen when comparing with an arm of surgery with/without radiotherapy alone.