Long-term outcomes after endoscopic endonasal surgery for nonfunctioning pituitary macroadenomas.

OBJECTIVE: Nonfunctioning pituitary adenomas are benign, slow-growing tumors. After gross-total resection (GTR) or subtotal resection (STR), tumors can recur or progress and may ultimately require additional intervention. A greater understanding of long-term recurrence and progression rates following complete or partial resection and the need for further intervention will help clinicians provide meaningful counsel for their patients and assist data-driven decision-making.

METHODS: The authors retrospectively analyzed their institutional database for patients undergoing endoscopic endonasal surgery (EES) for nonfunctioning pituitary macroadenomas (2003-2014). Only patients with follow-up of at least 5 years after surgery were included. Tumor volumes were measured on pre- and postoperative MRI. Tumor recurrence was defined as the presence of a 0.1-cm3 tumor volume after GTR, and tumor progression was defined as a 25.0% increase in residual tumor after STR.

RESULTS: A total of 190 patients were included, with a mean age of 63.8 ± 13.2 years; 79 (41.6%) were female. The mean follow-up was 75.0 ± 18.0 months. GTR was achieved in 127 (66.8%) patients. In multivariate analysis, age (p = 0.04), preoperative tumor volume (p = 0.03), Knosp score (p < 0.001), and Ki-67 (p = 0.03) were significant predictors of STR. In patients with GTR, the probability of recurrence at 5 and 10 years was 3.9% and 4.7%, and the probability of requiring treatment for recurrence was 0.79% and 1.6%, respectively. In 63 patients who underwent STR, 6 (9.5%) received early postoperative radiation and did not experience progression, while the remaining 57 (90.5%) were observed. Of these, the probability of disease progression at 5 and 10 years was 21% and 24.5%, respectively, and the probability of requiring additional treatment for progression was 17.5% and 21%. Predictors of recurrence or progression in the entire group were Knosp score (p < 0.001) and elevated Ki-67 (p = 0.03). Significant predictors of progression after STR in those who did not receive early radiotherapy were cavernous sinus location (p < 0.05) and tumor size > 1.0 cm3 (p = 0.005).

CONCLUSIONS: Following GTR for nonfunctioning pituitary adenomas, the 10-year chance of recurrence is low and the need for treatment even lower. After STR, although upfront radiation therapy may prevent progression, even without radiotherapy, the need for intervention at 10 years is only approximately 20% and a period of observation may be warranted to prevent unnecessary prophylactic radiation therapy. Tumor volume > 1 cm3, Knosp score ≥ 3, and Ki-67 ≥ 3% may be useful metrics to prompt closer follow-up or justify early prophylactic radiation therapy.