Osteosarcomas of the mandible: Are they different from other tumor sites?

Background: Osteosarcomas of the mandible (MOS) affect 1/10. million. persons/year, mostly the young adult. Due to lack of specific data, the treatment of MOS is extrapolated from that of extragnathic OS but varies widely between institutions. Materials and methods: We aimed at providing a focused description of MOS histologies and grades through the English literature, at determining the evidence-based role of chemotherapy, of adjuvant radiation therapy and the potential of reconstructive surgery tailored through modern pre-operative multi-modal imaging. Results: The estimated proportion of high grade MOS was 58%. However, low-grade MOS may be underestimated as they are mostly reported as case reports. The intermediate grade was hardly found in the literature. Estimated weighted-mean proportions of chondroblastic and osteoblastic MOS were 37% and 46%, respectively. Multimodal imaging modalities including MRI has a great potential for accurate pre-operative assessment of tumor extensions into bone and soft tissues. Surgery is the mainstay of treatment and margins the most important factor. The role of neoadjuvant chemotherapy in treating occult systemic metastases and in increasing the probability of clear margins is controversial, as well as the histology-dependent response to chemotherapy. The role of adjuvant radiotherapy (mostly proposed for positive margins) and/or adjuvant chemotherapy is still controversial. Crude survival is around 77% and local control around 67%. Local failure is the main cause of death in MOS compared to extragnathic sites.