Inherent Tumor Characteristics That Limit Effective and Safe Resection of Giant Nonfunctioning Pituitary Adenomas.

BACKGROUND: Surgical treatment of giant pituitary adenomas is sometimes challenging. We present our surgical series of giant nonfunctioning adenomas to shed light on the limitations of effective and safe tumor resection.

METHODS: The preoperative tumor characteristics, surgical approaches, outcome, and histology of giant nonfunctioning adenoma (>40 mm) in 128 consecutive surgical patients are reviewed. The follow-up period ranged from 19 to 113 months (mean 62.2 months).

RESULTS: A transsphenoidal approach was used in the treatment of 109 patients and a combined transsphenoidal transcranial approach in 19 patients. A total of 93 patients (72.7%) underwent total resection or subtotal resection apart from the cavernous sinus (CS). The degree of tumor resection, excluding the marked CS invasion, was lower in tumors that were larger (P = 0.0107), showed massive intracranial extension (P = 0.0352), and had an irregular configuration (P = 0.0016). Permanent surgical complications developed in 28 patients (22.0%). Long-term tumor control was achieved in all patients by single surgery, including 43 patients with adjuvant radiotherapy. Most tumors were histologically benign, with a low MIB-1 index (<3.0%) beside a few tumors mainly silent adenomas of pituitary-specific transcription factor lineage.

CONCLUSIONS: Irrespective of the surgical approach, massive intracranial extension, an irregular configuration, and marked CS invasion are inherent factors that independently limit effective resection. These high-risk tumors require an individualized therapeutic strategy.