NCOG-31. GIANT PITUITARY ADENOMA (GPA) SCORE: A NOVEL SCORING SYSTEM TO PREDICT POSTOPERATIVE OUTCOMES OF GIANT PITUITARY ADENOMAS

Abstract

Abstract BACKGROUND Giant pituitary adenomas (GPA) are uncommon and highly variable in morphology and extension. There is no scoring system that considers all the dimensions of adenoma invasion. We developed a new Giant Pituitary Adenoma score and report our surgical experience and evaluate outcomes after resection of these tumors in accordance with the preoperative score. METHODS We developed a novel scoring system for classifying giant pituitary adenomas, and 11-year data of GPA surgery at our center was collected retrospectively, based on this scoring system. GPA Score considered tumor’s parasellar extension, encasement of cavernous internal carotid artery (ICA), suprasellar extension > 2 cm, suprasellar extension > 4cm and retrosellar extension. Maximum possible score was 9. The scoring system was applied to 53 patients of GPA who underwent surgical resection between January 1, 2006, and December 2017. The Lundin-Pederson (ABC/2) method was used to calculate the tumor volume both pre- and post-resection and linear regression was used to assess the relationship between extent of tumor resection and GPA score. RESULTS The median age of the study population was 42.08 ± 16.49 years. The mean maximum diameter of the pituitary adenomas was 5.0 cm (range 4.0 cm-8.5cm) while the mean volume of the adenomas was 27.3 cm3 (range 10 cm3-149 cm3). There were 3 cases of score 2, 5 cases of score 3, 13 cases of score 4, 20 cases of score 5, 9 cases of score 6 and 3 cases of score 7. The range of tumor volumes of tumors for scores from 2-7 was 17.3 cm3 to 65.8 cm3 and GPA score was correlated with the percent residual tumor using linear regression that was statistically significant (p= 0.001). CONCLUSION GPA Score is a reliable scoring system to predict the extent and subsequent difficulty in tumor resection in GPA.