External Beam Radiation Therapy and Stereotactic Radiosurgery for Pituitary Adenomas

Department of Neurological Surgery, University of Virginia, 1240 Lee Street, Box 800212, Charlottesville, VA 22908, USA
Neurosurgery clinics of North America (Impact Factor: 1.54). 10/2012; 23(4):571-86. DOI: 10.1016/
Source: PubMed

ABSTRACT This article discusses contemporary use of external beam radiotherapy and stereotactic radiosurgery for pituitary adenoma patients. Specific techniques are discussed. In addition, indications and outcomes, including complications, are detailed.

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    ABSTRACT: Pituitary adenomas, although rare in the paediatric age range and mostly benign, represent very challenging disorders for diagnosis and management. The recent identification of genetic alterations in young individuals with pituitary adenomas has broadened the scope of molecular investigations and contributed to the understanding of mechanisms of tumorigenesis. Recent identification of causative mutations of genes such as GNAS, PRKAR1A, MEN1 and AIP has introduced the concept of molecular screening of young apparently healthy family members. Population-based studies have reported a significantly higher number of affected subjects and genetic variations than expected. Radiological techniques have advanced, yet many microadenomas remain undetectable on scanning. However, experience with transsphenoidal and endoscopic pituitary surgery has led to higher rates of cure. Prolactinomas, corticotroph and somatotroph adenomas remain the most prevalent, with each diagnosis presenting its own challenges. As paediatric pituitary adenomas occur very infrequently within the paediatric age range, paediatric endocrine units cannot provide expert management in isolation. Consequently, close co-operation with adult endocrinology colleagues with experience of pituitary disease is strongly recommended. © 2014 S. Karger AG, Basel.
    Hormone Research in Paediatrics 02/2014; 81(3). DOI:10.1159/000357673 · 1.71 Impact Factor
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    ABSTRACT: Background: Both fractionated external beam radiotherapy and single fraction radiosurgery for pituitary adenomas are associated with the risk of hypothalamic-pituitary (HP) axis dysfunction. Objective: To analyze the effect of treatment modality (Linac, TomoTherapy, or gamma knife) on hypothalamic dose and correlate these with HP-axis deficits after radiotherapy. Methods: Radiation plans of patients treated post-operatively for pituitary adenomas using Linac-based 3D-conformal radiotherapy (CRT) (n = 11), TomoTherapy-based intensity modulated radiation therapy (IMRT) (n = 10), or gamma knife stereotactic radiosurgery (n = 12) were retrospectively reviewed. Dose to the hypothalamus was analyzed and post-radiotherapy hormone function including growth hormone, thyroid stimulating hormone, adrenocorticotropic hormone, prolactin, and gonadotropins (follicle stimulating hormone/luteinizing hormone) were assessed. Results: Post-radiation, 13 of 27 (48%) patients eligible for analysis developed at least one new hormone deficit, of which 8 of 11 (72%) occurred in the Linac group, 4 of 8 (50%) occurred in the TomoTherapy group, and 1 of 8 (12.5%) occurred in the gamma knife group. Compared with fractionated techniques, gamma knife showed improved hypothalamic sparing for DMax Hypo and V12Gy. For fractionated modalities, TomoTherapy showed improved dosimetric characteristics over Linac-based treatment with hypothalamic DMean (44.8 vs. 26.8 Gy p = 0.02), DMax (49.8 vs. 39.1 Gy p = 0.04), and V12Gy (100 vs. 76% p = 0.004). Conclusion: Maximal dosimetric avoidance of the hypothalamus was achieved using gamma knife-based radiosurgery followed by TomoTherapy-based IMRT, and Linac-based 3D conformal radiation therapy, respectively.
    Frontiers in Oncology 04/2014; 4:73. DOI:10.3389/fonc.2014.00073
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    ABSTRACT: Purpose To investigate the safety and effectiveness of stereotactic radiosurgery (SRS) in patients with a silent corticotroph adenoma (SCA) compared with patients with other subtypes of non–adrenocorticotropic hormone staining nonfunctioning pituitary adenoma (NFA). Methods and Materials The clinical features and outcomes of 104 NFA patients treated with SRS in our center between September 1994 and August 2012 were evaluated. Among them, 34 consecutive patients with a confirmatory SCA were identified. A control group of 70 patients with other subtypes of NFA were selected for review based on comparable baseline features, including sex, age at the time of SRS, tumor size, margin radiation dose to the tumor, and duration of follow-up. Results The median follow-up after SRS was 56 months (range, 6-200 months). No patients with an SCA developed Cushing disease during the follow-up. Tumor control was achieved in 21 of 34 patients (62%) in the SCA group, compared with 65 of 70 patients (93%) in the NFA group. The median progression-free survival (PFS) was 58 months in the SCA group. The actuarial PFS was 73%, 46%, and 31% in the SCA group and was 94%, 87%, and 87% in the NFA group at 3, 5, and 8 years, respectively. Silent corticotroph adenomas treated with a dose of ≥17 Gy exhibited improved PFS. New-onset loss of pituitary function developed in 10 patients (29%) in the SCA group, whereas it occurred in 18 patients (26%) in the NFA group. Eight patients (24%) in the SCA group experienced worsening of a visual field deficit or visual acuity attributed to the tumor progression, as did 6 patients (9%) in the NFA group. Conclusion Silent corticotroph adenomas exhibited a more aggressive course with a higher progression rate than other subtypes of NFAs. Stereotactic radiosurgery is an important adjuvant treatment for control of tumor growth. Increased radiation dose may lead to improved tumor control in SCA patients.
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