SURG-56. TRANSCRIPTION FACTOR CELL LINEAGE DETERMINES AGGRESSIVE BEHAVIOR AMONG NONFUNCTIONAL PITUITARY ADENOMAS

Abstract INTRODUCTION Pituitary neuroendocrine tumors (PitNETs) are the second most common intracranial neoplasm. Silent or non-functional PitNETs represent a common neuro-oncological challenge due to their size and unpredictable invasion of parasellar structures. This makes their complete surgical resection difficult and puts patients at higher risk for recurrence. OBJECTIVE To characterize differences in tumor volume, cavernous sinus invasion, and recurrence in nonfunctional PitNETs. METHODS Out of 615 transsphenoidal surgeries from 2012 to 2024, there were 309 overall PitNETs and 181 nonfunctional PitNETs. Based on new WHO criteria for transcription factor profiling (PIT-1, TPIT, and SF-1), there were 98 silent gonadotroph adenomas (SGA), 31 silent corticotroph adenomas (SCA), 10 silent pleurihormonal tumors (PHT), and 2 null cell adenomas. Tumor volume was calculated using (AxBxC/2). Knosp grade was calculated. Cavernous sinus invasion was defined as Knosp ≥ 3. Residual disease at 3 months postoperative was recorded and surgical intervention for growing residual disease was captured. RESULTS Average tumor volume of PHT (18.08 cm3) was significantly higher than SGA (8.44 cm3, p=0.007) and similar to SCA (10.33 cm3, p=0.11). Percentage of cavernous sinus invasion was significantly different between SCA (31.82%) and SGA (10.20%, p=0.003), but not PHT (33.33%; p>0.05). There was a significantly higher residual rate in SCA compared to SGA (31.71% vs. 11.22%, p=0.006). There were significantly more reoperations in the SCA group compared to SGA and PHT. CONCLUSIONS Despite similar tumor volume between SCA and SGA, there was a significantly higher rate of cavernous sinus invasion and residual disease among SCA. This has important neuro-oncological implications regarding surgical technique, postoperative surveillance, and need for adjuvant therapy to mitigate aggressive recurrent disease.