Therapeutic Strategy for Cavernous Sinus-Invading Non-Functioning Pituitary Adenomas Based on the Modified Knosp Grading System

BACKGROUND: Non-functioning pituitary adenomas (NFPA) invading into the cavernous sinus are surgically challenging. To decrease recurrence rate, surgeon makes a strong endeavor to resect tumor gross totally. However, gross total resection (GTR) is difficult to achieve with cavernous sinus invasion. Recently, a new classification system for cavernous invasion of pituitary adenomas was suggested. The aim of this study is to validate this new classification system and to identify limitations and considerations in designing treatment strategies for patients with NFPA involving the cavernous sinus. METHODS: Between January 2000 and January 2012, 275 patients who underwent operation for NFPA were enrolled in the study. Median age was 50 years (15–79 years). There were 145 males and 130 females. The median follow-up duration was 4 years (range 1–12.5 years). RESULTS: Related to extent of tumor removal, GTR was obtained in 184 patients (66.9%), near total resection (NTR) was obtained in 45 patients (16.3%), and sub-total resection (STR) was obtained in 46 patients (16.7%) of a total 275 patients. There were statistically significant differences between the extent of resection and the new Knosp classification (p<0.001). In the high-grade group of the new Knosp classification, there was no difference in recurrence between patients who underwent GTR or NTR only and those who underwent STR with adjuvant radiation therapy (p=0.515). CONCLUSION: In case of high risk of surgical complications, STR with adjuvant radiation therapy can be considered as an alternative strategy for safe treatment of cavernous-invading adenomas.