Residual tumor volume in nonfunctional pituitary adenomas as a predictor of tumor recurrence: a volumetric study
Steven Waguespack, Ian McCutcheon, Amparo M. Wolf
Introduction: Nonfunctional pituitary adenomas (NFPA) recur postoperatively in 25-60% of patients. Analysis of impact of overall/subregional tumor volumes on postoperative recurrence is lacking for NFPAs, but would help in predicting recurrence risk for individual patients after resection.
Objective: To establish the relationship of preoperative and postoperative tumor volumes and extent of resection with recurrence in patients with NFPA.
Methods: This single-institution study includes NFPAs (n=276) operated 1993-2016 with follow-up > 1 year. Initial total tumor and cavernous sinus tumor volumes, postoperative residual volume, extent of resection, Hardy–Wilson classification, and Knosp grade were assessed.
Results: Median follow-up was 60 months. Tumor recurred in 19.9% (median 33 months; IQR, 22-50 months). 61.2% underwent gross total resection (GTR). Recurrence occurred after GTR (9.5%) and subtotal resection (36.4%) (X2 = 29.9, p < 0.001). Mean preoperative volume was 7.58 cm3 (95% CI 6.3-8.9%), mean preoperative cavernous sinus tumor volume 0.51 cm3 (95% CI 0.29-0.73%), mean residual volume 1.05 cm3 (95% CI 0.6-1.5%); mean extent of resection 91.8% (95% CI 89.4-94.2%). At 5 years 36% with resection<85% were recurrence-free vs. 71% after resection>85% (log rank X2 = 18.0 p < 0.001). Residual tumor>2 cm3 progressed in 44% by 5 years vs. 17% with residual<2 cm3 (log rank X2 = 18.0, p < 0.001). Significant predictors of recurrence on univariate analysis included prior surgery, higher preoperative Knosp grades (3 and 4), invasive Hardy grades (3 and 4, D and E), and silent corticotroph adenoma.
Conclusions: Residual NFPA volumes >2 cm3 or extent of resection <85% should prompt additional resection, adjuvant treatment, or close monitoring; they are most likely to progress within 5 years postoperatively.