Hábitos de sueño como factor de riesgo de cáncer de próstata

Abstract

In Spain, prostate cancer (PCa) is the first in incidence and fourth in mortality in men. Age, race, and family history are known, non-modifiable risk factors for PCa. Various factors related to lifestyle have been postulated as possible risk or protective factors for PCa, including sleep habits. To date, various approaches have been used to evaluate the relationship between PCa and sleep habits. We have worked with the duration and quality of sleep, the chronotype or the role of work shifts. The results of these approaches are not consistent. Additionally, few studies have directly evaluated the circadian cycle by determining melatonin levels. Through the data obtained from the CAPLIFE study, a population-based casecontrol study, we aim to: 1. Estimate the number of mean hours of sleep in the healthy population and the population with PCa and analyze its relationship with PCa based on the aggressiveness of the tumor. 2. Analyze the association between the person's chronotype - morning, evening and intermediate - and the risk of PCa, considering tumor aggressiveness. 3. Evaluate the impact of the work shift - daytime, permanent at night and rotating - on the risk of PCa based on the aggressiveness of the tumor. 4. Evaluate whether the chronotype behaves as a modifier of the effect of work shifts, as well as the individual's sleep habits on the risk of PCa. 5. Assess the circadian cycle, based on the rate of melatonin secretion in saliva, of men with PCa and healthy men, and its association with PCa. To carry out this study, men with and without PCa were selected from the Virgen de las Nieves and San Cecilio University Hospital (Granada). The following selection criteria were used: i) age 40-80 years; ii) residence for at least 6 months in the coverage area of the aforementioned hospitals; and iii) histologically confirmed diagnosis of PCa (only for cases). All cases were incident and selected before treatment. The sources of information used were: personal interview, medical history and biological samples of blood and saliva. This allowed the availability of sociodemographic information, lifestyle, Body Mass Index, occupational history, personal and family medical history, including the presence of a primary history of PCa, as well as dietary information. For the group of cases, information was also collected on urinary symptoms, aggressiveness and tumor extension. The main exposure variables were: i) duration of sleep; ii) chronotype; iii) work shifts (daytime, permanent at night or rotating) and their indicators (accumulated duration and intensity); and iv) melatonin rhythm measured through six determinations in 24 hours in saliva, and its amplitude and acrophase. Adjusted Odds Ratios and their 95% CIs were calculated using multivariate logistic regression models to estimate the association between sleep duration, chronotype, work shifts and PCa. The role of melatonin and CaP levels was analyzed using generalized estimation equations (GEE). Sleep duration and chronotype were not associated with PCa risk. Night shift occupation, specifically rotating shift, increased the risk of CaP. An interaction was observed between chronotype and years with night shift on PCa risk. When analyzing the rhythm of melatonin in saliva, the cases presented lower levels than the controls. This finding was independent of the urinary symptoms, aggressiveness and extension of the tumor. Furthermore, the greater the amplitude of the melatonin levels, the lower the risk of PCa. A late acrophase could be associated with an increased risk of PCa. The night shift, mainly rotating, the delay in acrophase and a low amplitude in the melatonin levels are associated with the risk of PCa, regardless of the urinary symptoms, aggressiveness and extension of the tumor. Sleep is a factor that should be considered in the etiology of PCa.