Development of hypopituitarism after fractionated pituitary radiotherapy for pituitary disease: a single-centre audit

Ramu Vathenen; Suhaniya Samarasinghe; Aiman Haddad; Luke Boyle; Karim Meeran; Emma Hatfield; Florian Wernig; Nigel Mendoza; Ramesh Nair; Asadullah Khan; Alison Falconer; Niamh Martin

doi:10.1530/endoabs.117.P179

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Endocrine Abstracts (2026) 117 P179 | DOI: 10.1530/endoabs.117.P179

SFEBES2026 Poster Presentations Neuroendocrinology and Pituitary (40 abstracts)

Development of hypopituitarism after fractionated pituitary radiotherapy for pituitary disease: a single-centre audit

Ramu Vathenen ¹ , Suhaniya Samarasinghe ² , Aiman Haddad ¹ , Luke Boyle ^1,3 , Karim Meeran ¹ , Emma Hatfield ¹ , Florian Wernig ¹ , Nigel Mendoza ⁴ , Ramesh Nair ⁴ , Asadullah Khan ⁵ , Alison Falconer ⁵ & Niamh Martin ¹

Author affiliations

¹Department of Endocrinology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom; ²MRC Laboratory of Medical Sciences, Imperial College London, London, United Kingdom; ³Department of Endocrinology, St Bartholomew’s Hospital, Barts Health NHS Trust, London, United Kingdom; ⁴Department of Neurosurgery, Charing Cross Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom; ⁵Department of Oncology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom

Introduction: Modern pituitary radiotherapy utilises techniques such as intensity modulated radiotherapy (IMRT) to reduce damage to healthy tissue. Rates of hypopituitarism vary significantly between studies (from 10% to greater than 40%). In this audit, we evaluated the frequency and timing of hypopituitarism in our centre in patients undergoing radiotherapy for pituitary tumours.

Methods: A retrospective review of all adult patients undergoing pituitary radiotherapy at a single centre between 2011 and 2018. Exclusion criteria included missing baseline or follow-up biochemistry. We recorded demographics, previous surgery, histology and radiotherapy technique from radiotherapy records and clinic letters. Each pituitary axis was documented as intact or deficient at baseline, and annually for 5 years post-radiotherapy. Deficiency was defined similarly to previous studies and Endocrine Society guidelines. Women over 50 years were excluded from gonadotrophin analysis.

Results: 40 patients fulfilled the above criteria of whom 33/40 received IMRT and 7/40 conformal radiotherapy. Of these, 55% were female with a mean age of 47.8 years and 39/40 had undergone previous pituitary surgery. Most tumours were adenomas (58% non-functioning) with 3 craniopharyngiomas. 43% of patients developed at least one new hormone deficiency by 5 years.

Table 1. Percentage of patients developing new hormone deficiency post-radiotherapy (n=number of patients included in analysis).
	Years after radiotherapy
	1	2	3	4	5
ACTH (n = 20)	30	35	35	35	35
TSH (n = 24)	12.5	20.8	20.8	29.2	29.2
Gonadotrophins (n = 15)	33.3	33.3	40	40	40
Growth hormone (n = 28)	17.9	17.9	17.9	17.9	17.9

Discussion: Our data shows that ACTH, gonadotroph and GH deficiency occurred mostly within the first year, with ACTH deficiency being diagnosed earlier than expected. The retrospective design and non-standardised assessments may introduce ascertainment biases (including potential over-diagnosis). Nevertheless, we suggest clinicians remain vigilant for hypopituitarism, with potential focus on ACTH deficiency within the first 1-2 years post-IMRT.