Efficiency of Stereotactic Radiotherapy in Acromegaly

Presentation Number: SUN 459
Date of Presentation: April 2nd, 2017

Gonca Oruk*1, Ali Olmezoglu2, Melda Apaydin3, Nurullah Yuceer3 and Eyüp Çoban3
1Izmir Katip Celebi University Ataturk Training and Research Hospital, Izmir, Turkey, 2Celal Bayar University, Manisa, Turkey, 3Izmir Ataturk Traininig and Research Hospital, IZMIR, Turkey


BACKGROUND: 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. Pituitary tumors are well-suited for Stereotactic Radiotherapy, since radiation can be focused on a well circumscribed region, while adjacent neural structures in the suprasellar and parasellar regions are precisely spared. The rates of hormonal normalization in patients with hypersecretory adenomas can vary considerably, and tends to be higher in patients with Cushing’s Disease and acromegaly (remission rate of approximately 53% and 54%, respectively) when compared with patients who have prolactinomas (24% remission) and Nelson’s syndrome (29%) remission. The aim of this study was to determine the efficacy and tolerability of fractionated Stereotactic Radiotherapy by CyberKnife in acromegaly.

METHODS: A retrospective review of biochemical and imaging data for subjects with acromegaly treated first with surgery and thereafter with Stereotactic Radiotherapy by CyberKnife (CK) for residual adenoma between 2011 and 2016 at Izmir Ataturk Training and Research Hospital was performed. In our institution 47 patients with active acromegaly were treated with fractionated Stereotactic Radiotherapy by CyberKnife (CK). Biochemical response rates based on serum insulin-like growth factor-1 (IGF-1), an oral glucose tolerance test with growth hormone (GH) measurements at 1st hour have been analyzed before CK treatment and during follow-up of the 1st, 3rd and 5 th years. Patients with GH ≤ 1 μg/L at 1st hour and/or IGF-1 < ULN (upper limit of normal; age and sex matched) levels were accepted as at normalised hormone level (under hormonal control).

RESULTS: In our study, median follow-up is 53 months (30-71 months) [SD: 11,40]. Eight of 47 patients had normalised hormone levels after the first year of CK radiation treatment concurrently using somatostatin analogue (SA) treatment. In addition to these patients, three years after receiving CK Radiotherapy, 9 patients also reached normal hormone levels with SA treatment. Two of 17 patients after first year, 3 of those after 3 years of CK treatment, totally 5 patients had hormonal and radiological complete response. Cumulative treatment assessment meant that 17 of 47 patients (36,10 %) had reached hormonal balance after 3 years of follow-up. Medical treatment was discontinued among complete responders (10.7 % of 47 patients). There has been no side effect of radiation treatment demonstrated after a mean follow-up of 50,61 months.

CONCLUSION: CyberKnife is considered extremely safe and effective among selected patients with acromegaly. However, longer follow-up is needed for a more detailed assessment of late toxicity and overall treatment efficacy.


Nothing to Disclose: GO, AO, MA, NY, EÇ