Early Versus Delayed Fractionated Stereotactic Radiotherapy for Nonfunctioning Pituitary Adenoma.

Background: Fractionated stereotactic radiotherapy (FSRT) is a common modality used to treat pituitary adenomas with good control rates. It is not known whether FSRT should be performed early or delayed until progression occurs. We compared FSRT in treating nonfunctional pituitary adenomas (NFPA) as an adjuvant (ADJ) or on-progression (PRG) therapy.

Methods: A retrospective review of patients who underwent FSRT for an NFPA between January 2004 and December 2022 at a single institution was performed. We compared endocrinologic, ophthalmologic, and radiographic outcomes in FSRT delivered as ADJ and PRG treatment.

Results: Seventy-five patients were analyzed, with a median follow-up of 53 months. FSRT was administered to 35 and 40 patients as ADJ and PRG, with a median time to treatment of 5.5 and 40 months, respectively. The tumor control rate was 94.3% for ADJ and 95.0% for PRG. Treatment resulted in 4 (11.4%) versus 7 (17.5%) new endocrinopathies and 2 (5.7%) versus 1 (2.5%) new visual deficits for ADJ versus PRG. A survival analysis of time to new endocrinopathy showed no difference between the 2 cohorts. The median time from surgery to new endocrinopathy was significantly different between ADJ and PRG, at 15.5 and 102.0 months, respectively.

Conclusions: FSRT is effective in treating NFPA for residual and progressive tumors, with excellent tumor control rates and a low risk of developing new endocrinopathies and visual deficits. Delaying treatment delayed the development of new endocrinopathies, suggesting that observation with FSRT on tumor progression may delay the onset of hypopituitarism and maintain similar effectiveness in tumor control.