Endocrine Abstracts

Objective: Melatonin is a hormone secreted by the pineal gland which modulates sleep and wakefulness rhythms. Decreased melatonin secretion has been shown to be associated with increased daytime sleepiness and disturbed circadian rhythm in (irradiated) survivors of childhood craniopharyngeoma. The present study was performed to explore possible relationships between disturbed sleep, psychosocial impairment and melatonin secretion in patients treated with cranial radiotherapy as a part of brain tumour or leukaemia treatment.

Patients and methods: Thirty four (16 m, 18 f) patients who had received radiotherapy as part of brain tumour treatment or leukaemia were investigated at least 3 year after completion of radiotherapy. In all patients overnight urine was collected and melatonin concentration and melatonin secretion/h was measured. Sleep quality was assessed using the pittsburgh sleep quality index (PQ3I) and daytime sleepiness using the epworth sleepiness scale (ESS). Quality of life was assessed with the short form- 36 (SF–36) and depression with the beck depression inventory-II (BDI-II). Tumors were divided into midline or near-midline tumours (n=15; i.e. germinoma medulloblastoma), non-midline (n=12; i.e.hemispheric) tumours and patients with leukaemia (n=7).

Results: Self-assessed sleep quality in the PQ3I or daytime sleepiness (ESS) were not linked to melatonin secretion and neither were BDI-II nor SF-36 scores. Melatonin concentrations were not dependent on radiation dose, elapsed time since radiotherapy, age at radiotherapy, or childhood versus adult-onset of brain tumour disease (n.s.). Patients irradiated for midline tumours had a significantly lower overall melatonin secretion and hourly melatonin secretion than patients irradiated for non-midline tumours (P=008).

Conclusion: Melatonin secretion was linked to brain tumour site and, thus, perhaps also radiation dose to the pineal gland. Since melatonin secretion was not associated with sleep quality or psychosocial impairment, the medical use of exogenous melatonin in such patients must be questioned.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.