**8. Prognosis**

Weber and his colleagues have recognized histology, gross tumor volume, and brain compression as prognostic feature for local control for chondrosarcomas and chordomas as well as overall survival (OS) based on multivariate investigation [55]. Dedifferentiated chordomas usually display a poor prognosis and this subtype contains a 60% 3-year OS compared to an 89.4% 3-year OS for classical chordomas [8]. Bloch and his colleagues have revealed that grade III chondrosarcomas appear with aggressive behavior and are related with the most reduced survival rates [56]. They calculated a 5-year mortality rate was 11.5% in a systematic review of 560 patients with intracranial chondrosarcomas and median survival time of 2 years. The conventional and chondroid variants of chordoma have a favorable long-term prognosis, with a 3-year survival rate of 90% [57]. The dedifferentiated subtype shows aggressive behavior and the 3-year overall survival rate is around 60% [58].

### **9. Future aspects**

Chordoma may be a malignant tumor with a few confusing highlights, such as its origin, and its neighborhood invasiveness, and moderate aggressive character. To conclude, in spite of the fact that the myxoid variation of chondrosarcoma and chondroid chordoma are comparative in a few viewpoints, they vary in their origin. Cranium base myxoid chondrosarcoma carries an extraordinarily more favorable result with negligible recurrence though chordomas counting its chondroid variant illustrates an aggressive clinical course with consistently destitute outcome after disease recurrence. Radiotherapy is usually suggested after surgery in chordoma, while resection of the tumor suffices in the myxoid variant of chondrosarcoma. Immunohistochemistry is the most common application of immunostaining and it is also widely used to differentiate chondrosarcoma and chordoma and understand the scattering and localization of biomarkers and differentially expressed proteins in different cellular parts of chondrosarcoma and chordoma.

In spite of the advance in current surgical strategies and some encouraging results with the use of targeted therapy, control of the disease and long-term patient prognosis are still not satisfactory. However, understanding of the molecular basis of chordoma pathophysiology hopefully will give us a better understanding to improve the prognosis of this rare malignancy. Currently, surgical resection is the favored treatment for chordoma, whereas recent advances are focused on curative treatment and advanced radiotherapy may play for the treatment of chordoma, and surgery will be done only for the most advanced cases of chordoma.
