Issues in formidable skull base tumors

Treating skull base tumors require long-term tumor control and preservation of neurological functions. Malignant skull base tumors, such as cancers or sarcomas originating in the nasal or paranasal sinuses, are treated by en bloc resection with tumor-free margins. Five-year survival rates of en bloc resection have been 60~70%. Analysis of long-term outcome is necessary to clarify the role of proton beam or heavy ion radiotherapies. Chordomas require surgical resection and high-dose radiation. Five-year survival rates have been 60~80%. Radical resection including the surrounding bone is important for tumor control. Extended endonasal endoscopic surgery and proton beam or heavy ion radiotherapies could become standard treatments after confir-mation of their long- term outcomes. Skull base meningiomas are currently treated using surgical resection and stereotactic radiotherapy. Precise planning of surgical procedures and the goals of tumor removal are important to obtain satisfactory surgical outcomes. Skull base meningiomas can be clinically malignant with invasive and rapid growing characteristics, quick recurrence, or malignant- transformation. Diagnosis of clinically malignant men-ingiomas might change surgical strategies in the future. Also, the timing of stereotactic radiotherapy (immedi-ately after surgery vs. after confirming remnant tumor growth) has been controversial. Consequently, the analysis of long-term outcomes (more than 10 or 20 years) of stereotactic radiotherapy is mandatory to elucidate the best timing and possibility of malignant transformation or second cancer formation.