Treatment strategy for sinonasal malignant tumor with skull base invasion

We examine considerations for determining treatment strategies in sinonasal malignancies with skull base invasion. A retrospective study was conducted of 92 patients (including 68 sinonasal malignancies) who had been treated in Tohoku University Hospital. Twenty patients underwent skull base surgery after pretreatment diagnostic imaging for dural invasion. Gadolinium enhanced MRI showed dural enhancement in 18 of these patients. Subsequent histological examination indicated that 10 of these 18 had dural invasion. Low apparent diffusion coefficients (ADC) had been previously detected in these patients. Eighteen patients in our study had been treated with RADPLAT. In 7 of the 18 patients, computed tomography angiography (CTA) and digital subtraction angiography (DSA) revealed that the blood flow to the tumor was from a branch of an internal carotid artery such as the ophthalmic artery, rendering the treatment ineffective. Six of these 7 patients were T4b patients. For the 20 TPF-CCRT patients the five-year overall survival rate was 58.3% and the five-year progression-free survival rate was 50% . Based on these results, we suggest that diagnostic imaging prior to either surgery or RADPLAT treatment is important. The combination of dural enhancement and low ADC appears to indicate that surgery is an appropriate treatment. ADC and DSA imaging is critical prior to RADPLAT since only tumors fed from the external carotid will respond to treatment. When surgery and RADPLAT are not indicated, TPF-CCRT would be the best treatment option.