Long-term anterior pituitary function in patients with paediatric Cushing's disease treated with pituitary radiotherapy

Background/objective: Pituitary radiotherapy (RT) is an effective second-line treatment for paediatric Cushing's disease (CD). Although the short-term effects of pituitary RT are well documented, there are less data on possible long-term sequelae. We report the long-term anterior pituitary function in a cohort of paediatric CD patients treated with pituitary RT. Patients and methods: Between 1983 and 2006, 12 paediatric CD patients (10 males and 2 females) of mean age 11.4 years at diagnosis (range 6.4-17.4) underwent second-line pituitary RT (45 Gy in 25 fractions), following unsuccessful transsphenoidal surgery. Out of 12, 11 patients were cured by RT (cure interval 0.13-2.86 years) defined by mean serum cortisol of < 150 nmol/l on 5-point day curve and midnight sleeping cortisol of < 50 nmol/l. Long-term data are available for six male patients, who received RT at the age of 7.0-17.6 years. The mean follow-up from the completion of RT was 10.5 years (6.6-16.5). Results: At a mean of 1.0 year (0. 11-2.54) following RT, GH deficiency (peak GH < 1-17.9 mU/l) was present in five out of six patients. On retesting at a mean of 9.3 years (7.6-11.3) after RT, three out of four patients were GH sufficient (peak GH 19.2-50.4 mU/l). Other anterior pituitary functions including serum prolactin in five out of six patients were normal on follow-up. All the six patients had testicular volumes of 20-25 ml at the age of 14.5-28.5 years. Conclusion: This series of patients illustrates the absence of serious long-term pituitary deficiency after RT and emphasises the importance of continued surveillance.