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Pituitary radiotherapy 

Pituitary radiotherapy
Chapter:
Pituitary radiotherapy
Author(s):

Thankamma Ajithkumar

and Michael Brada

DOI:
10.1093/med/9780199235292.003.2109
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date: 14 December 2019

External beam radiotherapy remains an important component of management of patients with pituitary adenoma and a considerable proportion of patients receive it during the course of their illness. Traditional policy had been to use radiotherapy for all patients with residual nonfunctioning pituitary adenoma after surgery as the majority were considered to progress (1). With improvement in surgical techniques and access to MRI, postoperative radiotherapy is no longer routinely employed even in the presence of residual tumour. The use of radiotherapy is based on relative risk assessment, generally withholding further treatment until progression unless there is a perceived threat to function, particularly vision, if the tumour was to progress. Currently radiotherapy is used in patients with progressive nonfunctioning adenoma demonstrated on interval imaging and achieves tumour control in over 90% of patients at 10 years and 85–92% in 20 years (1–9). Radiotherapy remains an integral component of treatment of patients with secreting adenoma who fail to achieve biochemical cure following surgery and medical treatment and in patients with progressive/recurrent tumour mass regardless of the status of hypersecretion. The slow rate of decline in hormone levels means that normalization takes months to years and the delay is primarily related to pretreatment hormone levels. Nevertheless radiotherapy leads to normalization of excess hormone secretion in the majority of patients.

The past two decades have seen developments in radiotherapy, which can largely be considered as refinement of existing technology. The principal aim of modern high-precision, localized radiotherapy is to treat less normal tissue to significant radiation doses therefore minimizing the risk of late normal tissue injury. The higher precision relies on increased accuracy of tumour delineation using modern imaging. The overall success of modern high-precision treatment is more likely to be related to the treatment centre infrastructure and expertise and the accuracy in identifying the tumour than the exact equipment used.

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