Early versus Delayed Fractionated Stereotactic Radiotherapy for Residual and Progressive Nonfunctioning Pituitary Adenomas

Objective Radiation therapy is a common modality used to treat residual and recurrent pituitary adenomas. Stereotactic radiosurgery (SRS) is frequently used with good control rates. Fractionated stereotactic radiotherapy (FSRT) has recently been shown to be a viable alternative with similar outcomes to SRS. It is currently unknown whether the radiation should be performed early for residual tumor, or should be delayed until progression occurs. We sought to compare the role of FSRT in the early treatment of residual versus delaying treatment until progression occurs.

Methods A retrospective review was performed on all patients who underwent FSRT for a nonfunctioning pituitary adenoma between January 2004 and November 2016 at Thomas Jefferson University. A subgroup analysis was performed comparing the endocrinologic, ophthalmologic, and radiographic outcomes in residual versus progressive disease in pituitary adenoma.

Results A total of 66 patients were analyzed, with a mean follow-up of 45.3 months. Cavernous sinus involvement and optic apparatus abutment were present in 63.6 and 43.9% of patients, respectively. The median FSRT treatment dosage was 50.4 Gy over 28 fractions, with a mean treatment volume of 12.3 mm³. All patients achieved radiographic control, with 15.2% attaining a decrease in tumor size. The incidence of a new endocrinopathy was 3.0%, and visual deficit was 1.5%.

FSRT for residual and progressive disease occurred in 34 (mean time to treatment: 8.4 months) and 32 (mean time to treatment: 55.8 months; p < 0.01) patients, respectively. The mean treatment volume was 17.2 versus 6.9 mm³ (p < 0.05). Treatment for progressive disease resulted in two new endocrinopathies, whereas the one case of postradiation visual deficit occurred in the treatment for residual disease. There was no significant difference in tumor control rates with FSRT for residual versus progressive disease.

Conclusion FSRT is a durable treatment modality for the treatment of progressive and residual pituitary macroadenomas, and can decrease tumor size in up to 15% of patients. It results in in excellent tumor control rates comparable to SRS with a low risk of developing new endocrinopathies and visual deficits. The early and delayed FSRT results in excellent tumor control rates with low morbidities.