Melatonin levels lower in prostate cancer patients

Patients with prostate cancer (PCa) have lower levels of melatonin than those without PCa, independent of urinary symptomatology or extension and aggressiveness of the tumour, a study has found.

A team of investigators analysed 40 PCa cases and 41 controls from the CAPLIFE study to determine the salivary melatonin rhythm through six saliva samples. Amplitude (maximum melatonin peak) was categorized as low or high using the median cutoff point of the controls, while acrophase (time of maximum melatonin peak) was classified as early or late using the same criteria.

The investigators also collected the following data: characteristics related to sleep habits and clinical and sociodemographic information. Using logistic regression models, they calculated the adjusted odds ratio (aOR) and 95 percent confidence interval (CI) to estimate the association between amplitude, acrophase, and PCa.

Melatonin rhythms were represented for cases and controls and analysed according to urinary symptoms, tumour aggressiveness, and tumour extension. Finally, generalized estimating equations on the ln-transformed values were used to assess variations in melatonin levels.

The mean age of PCa patients and controls was 67.0 and 67.5 years, respectively. PCa patients always had lower melatonin levels, with an average of ‒64.0 percent (95 percent CI, ‒73.4 to ‒51.4), than controls. Likewise, amplitude was lower in PCa patients compared with control participants (26.0 vs 46.3 pg/ml; p<0.001).

Of note, a high amplitude level correlated with a reduced risk of PCa (aOR, 0.31, 95 percent CI, 0.11‒0.86), while a late acrophase correlated with a higher PCa risk (aOR, 2.36, 95 percent CI, 0.88‒6.27).