ECE2022 Oral Communications Young Investigator Awards (12 abstracts)
1Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom; 2Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, United Kingdom; 3Department of Endocrinology, Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom; 4Oxford Centre for Diabetes, Endocrinology and Metabolism, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom; 5Department of Diabetes and Endocrinology, Leeds Teaching Hospitals NHS Trust, St Jamess University Hospital, Leeds, United Kingdom; 6Department of Diabetes and Endocrinology, University Hospitals of Leicester NHS Trust, Leicester Royal Infirmary, Leicester, United Kingdom; 7Section of Endocrinology & Internal Medicine, Department of Medical Sciences, University of Ferrara, Ferrara, Italy, Italy; 8Department of Oncology, Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom; 9Department of Clinical Oncology, Oxford University Hospitals NHS Trust, Oxford, United Kingdom; 10Bristol Haematology and Oncology Centre, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, United Kingdom; 11Department of Endocrinology, Bristol Royal Infirmary, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, United Kingdom
Background: The risk of a second brain tumour following radiotherapy for pituitary adenoma or craniopharyngioma in adults is currently unclear. Studies are methodologically limited by small patient sample size, few case events, selection biases or the use of inappropriate controls.
Objective: To ascertain whether radiotherapy delivered to adults with pituitary adenoma or craniopharyngioma is associated with an increased second brain tumour risk using appropriate methodology.
Design: Multicentre, retrospective cohort study involving six adult endocrine centres.
Methods: 4,292 patients with pituitary adenoma or craniopharyngioma detected until 31st December 2013 were identified from departmental registries. Patients with one image, unknown radiotherapy exposure status, genetic predisposition, history of brain tumour prior to study entry, or aged <18 years at the time of radiotherapy, were excluded (n=598). Recipients of proton or stereotactic radiotherapy (n=81) were also excluded from statistical analyses, such that data were explored for 930 patients exposed to conventional, 3D-CRT or IMRT and 2,683 controls. Follow-up was defined by imaging dates from the time of radiotherapy until last imaging in the exposure group, and from the time of pituitary tumour detection until last imaging in the control group.
Results: Over 43,887 patient-years (12,674 radiotherapy, 31,213 controls), second brain tumours were reported in 58 patients (27 radiotherapy, 31 controls): 6 were malignant (4 radiotherapy, 2 controls, and 52 benign (23 radiotherapy, 29 controls). Older age at pituitary tumour diagnosis and radiotherapy exposure were associated with increased risk of second brain tumour (HR 1.036, 95%CI 1.018-1.055, P<0.0001 and HR 1.744, 95% CI 1.040-2.927, P=0.035, respectively), but tumour type and sex were not. After adjusting for age, radiotherapy exposure was associated with an increased risk of second brain tumour (HR 1.728, 95%CI 1.029-2.902, P=0.031). Cumulative probability of second brain tumour at 20 years was 4.2% and 2.1%, for the radiotherapy group and control group, respectively. Incidence rate ratio of irradiated versus controls was 2.15 (95%CI 1.27-3.60, P=0.005). Median latency after radiotherapy was 8.1 years (7.5-27.3) for malignant and 17.2 years (3.0-50.8) for benign tumours, respectively.
Conclusions: This is the first study assessing the risk of a second brain tumour in a cohort of non-selected irradiated adults and appropriate controls with confirmed long-term imaging surveillance. The risk of second brain tumour following radiotherapy (conventional, 3DCRT or IMRT) for pituitary tumours is increased, although less than previously reported. Our results inform clinical practice and provide data to be used when counselling patients on the risks of radiotherapy.