Men with prostate cancer have lower levels of melatonin, the sleep-inducing hormone, than the population without cancer

Research led by researchers from the University of Granada (UGR), belonging to the Preventive Medicine and Public Health research group of the Granada Biosanitary Research Institute (ibs.GRANADA), has revealed that men with prostate cancer have high levels lower levels of melatonin, the sleep-inducing hormone, than men without cancer, regardless of urinary symptoms, the extent and aggressiveness of the tumor they suffer from.

This work is part of the CAPLIFE study (prostate cancer and lifestyles), whose main researcher is Professor Rocío Olmedo Requena, from the Department of Preventive Medicine and Public Health of the University of Granada, and has been published in the journal Journal of Urology. It is part of the results of the doctoral thesis of Macarena Lozano Lorca, supervised by professors Jiménez-Moleón and Olmedo-Requena.

As Rocío Olmedo explains, “circadian cycles regulate a large part of the functions of our body, they last approximately 24 hours and are regulated by melatonin levels. This hormone is produced in the absence of light, and is linked to the light-dark cycle.

Its maximum levels are reached at night, although its production is conditioned by age and can be affected by the season of the year (lower levels at advanced ages and during the spring-summer months). Light pollution can also affect melatonin levels, including the use of electronic devices at night. The International Agency for Research on Cancer classifies night shift work as a probable carcinogen, and melatonin may be one of the factors that may underlie this association.

Despite the fact that we spend a third of our lives sleeping, to date little attention has been paid to this lifestyle and its relationship with health. The study of sleep can be carried out from multiple approaches (sleep duration and quality, work shift including night or rotating work, level of existing light pollution, etc.), although the most objective measurement is through the analysis of the circadian rhythm at from melatonin levels at different points of the day.

To analyze for the first time the relationship between melatonin levels and prostate cancer, in this study six saliva samples per participant were collected over a 24-hour period, in 40 subjects newly diagnosed with prostate cancer and 41 men without prostate cancer. this pathology. This allowed us to know the melatonin levels in each of the points, its amplitude (defined by the maximum production peak), as well as the acrophase (time at which the maximum production peak occurs).

A lower melatonin spike

The scientists observed that in subjects with prostate cancer, melatonin levels were systematically lower than those of men without this pathology, regardless of age, season of the year, symptoms associated with prostate cancer and the degree of progression of the disease. In addition, the time in which it occurred was later. Concluding that, in the sample studied, melatonin levels in men with prostate cancer, regardless of urinary symptoms, tumor extension and aggressiveness, were always lower than those of men without this pathology.

This research has been carried out within the ibs.GRANADA Institute thanks to the collaborative work between researchers from the University of Granada, the International Institute of Melatonin, the Urology Services of the Virgen de las Nieves University Hospital and the San Cecilio Clinical University Hospital, the Andalusian School of Public Health and the Granada-Metropolitan Health District. Being, in addition, part of the authors of this article members of the CIBER of Fragility and Healthy Aging (CIBERFES) and of the CIBER of Epidemiology and Public Health (CIBERESP).