Advanced therapeutic strategy for radiation-induced osteosarcoma in the skull base: a case report and review

A review of patients with skull base osteosarcoma secondary to radiation (radiation-induced osteosarcoma: RIOS) of the pituitary tumor shows the mean survival of approximately 7 months (2 weeks – 16 months). This warning prognosis seems to stem from two factors, 1) the anatomical complexity of the skull base for total resection of the tumor, and 2) standard adjuvant therapies for the tumor yet to be established. Contrary to the general belief, the authors report an unusually long survival of a 75-year-old woman with a history of osteosarcoma that developed in the same sequence 20 years after pituitary tumor radiation. On her recent admission, she complained of frontal headaches and MRI studies showed a tumor in the sphenoid sinus. Endoscopic trans-nasal tumor removal allowed for histological diagnosis of an osteosarcoma. However, further rapid tumor growth necessitated a radical tumor resection followed by a combined chemotherapy with ifosfamide, cisplatin, and etoposide (ICE). Despite temporary suppression of the tumor growth, the chemotherapy was discontinued due to severe pancytopenia that occurred after three courses of treatment. Shortly after the discontinuation of ICE therapy, the tumor size increased again rapidly, requiring a novel radiation therapy, Cyber-knife treatment. Following this radiation, the tumor growth was arrested, and the patient remains healthy without neurological symptoms over 24 months. The outcome of Cyber-knife in this case suggests that this specific therapy must be considered for the unresectable skull base RIOS.