Temporal profile of serum melatonin levels in paediatric pineal tumours subjected to surgery: newer insights.

Introduction: Pineal tumours (PTs) are rare and histologically variable. Serum melatonin is a well-known product of this gland, albeit with uncertain clinical implications vis-à-vis its utility as a potential tumour marker. In particular, the temporal profile of serum melatonin during the disease course remains unclear and infrequently studied.

Methods: Ten children with pineal tumours were prospectively studied over 2 years. Midnight serum melatonin levels were estimated before and after surgery (6-week postoperatively) and at the time of clinical-radiological progression. Different clinical, radiological, histological and treatment variables were correlated with the mean change in the pre- and postoperative serum melatonin levels using statistical methods.

Results: Histopathologically, 5 of these cases (50%) were pineal cell tumours, while the rest were tumours of non-pineal cell origin. The mean preoperative serum melatonin level was 94.9 pg/ml (range 20-397 pg/ml), while the mean postoperative level was 69.6 pg/ml (range 45-156 pg/ml; in one case, the levels became non-detectable). Tumour histology (p = 0.04) and gender (p = 0.03) correlated with high preoperative serum levels. While the change in overall mean value did not have any statistical significance (effect size 0.29, p value 0.340), postoperative serum melatonin elevation was significant in tumours of non-pineal cell origin (large effect size 0.93, p value 0.004).

Conclusion: The serum melatonin may be affected by age, gender and symptom duration. However, the dynamic of serum melatonin in the perioperative period is largely dependent on the cell of origin of the PT.