Roles of skull base surgery and particle radiotherapy for orbital malignant tumors involving the skull base

Purpose To investigate the oncological outcomes of orbital malignant tumors invading the skull base. Methods A retrospective analysis was conducted on 16 patients with orbital malignant tumors invading the skull base. Eleven patients were treated with skull base surgery, four patients were treated with particle therapies, and one patient was treated with chemoradiotherapy (CRT) as initial treatment. Results The most frequent histological type was adenoid cystic carcinoma in seven patients, followed by squamous cell carcinoma in two patients. Local recurrence occurred in two of the six surgically treated patients who did not receive postoperative radiotherapy (RT) or CRT. One of them was successfully salvaged by RT, and the other died of disease. With a median follow-up of 24 months, the 2-year overall, local control, and disease-free survival rates of all patients were 82.5%, 87.5%, and 59%, respectively. Conclusions Patients with positive surgical margins were at risk of local recurrence. Postoperative RT should be considered for all surgically treated patients. Level of Evidence: 4.