Task: Answer Verification
Input (English): Question: Are differences in dural penetration of clival chordomas associated with different prognosis and expression of platelet-derived growth factor receptor-β?
Answer: Clival chordomas have different degrees of dural penetration. Patients with chordomas with serious dural penetration have poorer prognosis. Higher expression of PDGFR-β is related to more serious dural penetration of clival chordomas.
Output (English): yes