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Updated: Jul 23, 2025
Stereotactic Radiosurgery for Gynecologic Cancer
Published on: April 17, 2012
Volumetric Assessment of Nonfunctional Pituitary Adenoma Treated With Stereotactic Radiosurgery: An Assessment of
Sam Dayawansa1, Salma O Abbas2, Georgios Mantziaris1
1Department of Neurological Surgery, University of Virginia, Charlottesville , Virginia , USA.
Background And Objectives:
Stereotactic radiosurgery (SRS) is widely used to manage recurrent or residual nonfunctioning pituitary adenomas (NFPAs). Studies on the long-term volumetric response of NFPAs to SRS are lacking. Such a post-SRS volumetric study will allow us to set up appropriate radiographic follow-up protocols and predict tumor volumetric response.
Methods:
Two providers independently performed volumetric analyses on 54 patients who underwent single-session SRS for a recurrent/residual NFPA. In the case of discrepancy between their results, the final volume was confirmed by an independent third provider. Volumetry was performed on the 1-, 3-, 5-, 7-, and 10-year follow-up neuroimaging studies.
Results:
Most patients showed a favorable volumetric response, with 87% (47/54) showing tumor regression and 13% (7/54) showing tumor stability at 10 years. Year 3 post-SRS volumetric results correlated (R 2 = 0.82, 0.63, 0.56) with 5-, 7-, and 10-year outcomes. The mean interval volumetric reduction was 17% on year 1; further interval volumetric reduction was 17%, 9%, 4%, and 9% on years 3, 5, 7, and 10, respectively.
Conclusion:
Year 3 post-SRS volumetric response of patients with residual or recurrent NFPAs is predictive of their 7-10-year follow-up response. For patients demonstrating NFPA regression in the first 1-3 years, interval follow-up MRI's can likely be performed at 2-year periods unless otherwise clinically indicated. Further studies are needed to better define the volumetric response to adenomas more than a decade after SRS.
