Acromegaly is a disease characterized by GH hypersecretion, and is typically caused by a pituitary somatotroph adenoma. The primary mode of therapy is surgery, and radiotherapy is utilized as an adjuvant strategy to treat persistent disease. The aim of this study was to determine the efficacy and tolerability of CyberKnife stereotactic radiosurgery in acromegaly.
A retrospective review of biochemical and imaging data for subjects with acromegaly treated with CyberKnife stereotactic radiosurgery between 1998 and 2005 at Stanford University Hospital.
Nine patients with active acromegaly were treated with radiosurgery using the CyberKnife (CK).
Biochemical response based on serum insulin-like growth factor-1 (IGF-1), anterior pituitary hormone function, and tumor size with MRI scans were analyzed.
After a mean follow up of 25.4 months (range, 6-53 months), CK radiosurgery resulted in complete biochemical remission in 4 (44.4%) subjects, and in biochemical control with the concomitant use of a somatostatin analog in an additional subject. Smaller tumor size was predictive of treatment success: baseline tumor volume was 1.28 cc (+/- 0.81, SD) vs. 3.93 cc (+/- 1.54) in subjects with a normal IGF-1 vs. those with persistent, active disease, respectively (P = 0.02). The mean biologically effective dose (BED) was higher in subjects who achieved a normal IGF-1 vs. those with persistent, active disease, 172 Gy(3) (+/-28) vs. 94 Gy(3) (+/-17), respectively (P < 0.01). At least one new anterior pituitary hormone deficiency was observed after CK in 3 (33%) patients: two developed hypogonadism, and one developed panhypopituitarism.
CK radiosurgery may be a valuable adjuvant therapy for the management of acromegaly.
"In a report of nine patients with acromegaly treated with CyberKnife to doses of 18–24 Gy in one to three fractions, biochemical remission was observed in 4 patients at a mean followup of 25.4 months . Whilst these results are promising, the short followup and the small number of patients do not permit any conclusion about the low risk of optic neuropathy in patients treated with hypofractionated regimens. "
[Show abstract][Hide abstract] ABSTRACT: Radiotherapy (RT) is often employed in patients with acromegaly refractory to medical and/or surgical interventions in order to prevent tumour regrowth and normalize elevated GH and IGF-I levels. It achieves tumour control and hormone normalization up to 90% and 70% of patients at 10-15 years. Despite the excellent tumour control, conventional RT is associated with a potential risk of developing late toxicity, especially hypopituitarism, and its role in the management of patients with GH-secreting pituitary adenomas remains a matter of debate. Stereotactic techniques have been developed with the aim to deliver more localized irradiation and minimize the long-term consequences of treatment, while improving its efficacy. Stereotactic irradiation can be given in a single dose as stereotactic radiosurgery (SRS) or in multiple doses as fractionated stereotactic radiotherapy (FSRT). We have reviewed the recent published literature on stereotactic techniques for GH-secreting pituitary tumors with the aim to define the efficacy and potential adverse effects of each of these techniques.
International Journal of Endocrinology 02/2012; 2012:482861. DOI:10.1155/2012/482861 · 1.95 Impact Factor
"Initial experiences with the application of CyberKnife SRS or hypofractionated SRT in treating patients with acromegaly are promising [52,53]. In a report of nine patients with acromegaly treated with CyberKnife to doses of 18-24 Gy in one to three fractions, biochemical remission was observed in 4 patients at a mean follow up of 25.4 months . The efficacy of hypofractionated treatment schedules which may offer a reduced risk of radiation-related adverse effects as compared to single fraction radiosurgery needs to be evaluated in future studies. "
[Show abstract][Hide abstract] ABSTRACT: Radiotherapy (RT) remains an effective treatment in patients with acromegaly refractory to medical and/or surgical interventions, with durable tumor control and biochemical remission; however, there are still concerns about delayed biochemical effect and potential late toxicity of radiation treatment, especially high rates of hypopituitarism. Stereotactic radiotherapy has been developed as a more accurate technique of irradiation with more precise tumour localization and consequently a reduction in the volume of normal tissue, particularly the brain, irradiated to high radiation doses. Radiation can be delivered in a single fraction by stereotactic radiosurgery (SRS) or as fractionated stereotactic radiotherapy (FSRT) in which smaller doses are delivered over 5-6 weeks in 25-30 treatments. A review of the recent literature suggests that pituitary irradiation is an effective treatment for acromegaly. Stereotactic techniques for GH-secreting pituitary tumors are discussed with the aim to define the efficacy and potential adverse effects of each of these techniques.
[Show abstract][Hide abstract] ABSTRACT: Optimal management of pituitary adenomas involves consideration of the roles of medical therapy, surgery, and radiation therapy. The different forms of radiation therapy and their results are reviewed here.
A literature search through the U.S. National Library of Medicine was used to identify and review clinical experiences of radiation therapy in the management of pituitary adenomas. Emphasis was placed on studies within the last 5-10 yr, with 5 or more years of follow-up data, and of reasonable quality of data. Older studies with larger numbers or particular significance are also highlighted.
Success of radiation therapy in controlling tumor growth is high, 90-100% in most series, regardless of radiation technique and adenoma subtype. Success in achieving hormonal normalization in secretory tumors is more variable because of differences in patient population, radiation technique, and doses employed and variation of the definition of success. Complete biochemical remission is generally achieved in 50% of patients at 10 yr after treatment for most adenomas. Higher rates of normalization can be achieved with additional medical therapy. Hypopituitarism is an expectant result of radiation therapy. Overall rate of other treatment-related adverse effects is low.
Radiation therapy should be considered in the management of patients with pituitary adenomas, particularly when medical and surgical options have been exhausted. Because response evolves slowly over many years and because hypopituitarism is likely to occur, patients should be counseled on the importance of continued endocrinological surveillance and medical management.
The Journal of Clinical Endocrinology and Metabolism 04/2011; 96(7):1992-2003. DOI:10.1210/jc.2011-0251 · 6.21 Impact Factor
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