Una sistematica revisione della letteratura concernente la possibile associazione tra lavoro e turni/tumori

In 2007, IARC classified “shiftwork that involves circadian disruption” as “probably carcinogenic to humans (2A)”, referring to breast cancer in particular, but with some evidence for prostatic, colorectal and endometrial cancers. The plausible physiopathological mechanisms deal with light exposure at night and dis-regulation of the biological clock and connected circadian rhythms, alterations in clock gene expression and function, and interference on neuroendocrine system and immune surveillance due to chronic sleep deprivation. Many experimental studies on animals clearly show an association between “circadian disruption”, resulting from manipulation of the light/dark cycle, and cancer growth
per se
or after exposure to chemical carcinogens or tumor xenografts. The 27 (15 positive) epidemiological studies on humans carried out so far show major limitations with respect to both the rather crude definition of shift and night work, and the partial control for confounding or concurrent risk factors. In this perspective, a group of experts suggested that new studies should report more detailed information about shift schedules (e.g. rotating/fixed, night shifts, speed/direction of rotation) able to define the potential for circadian disruption, as well as other information on exposure to light at night, sleep habits, personal characteristics (i.e. morningness) and biomarkers (i.e. melatonin) able to influence and better detect circadian desynchronization. Such issues need urgent attention since breast and prostate cancers are two of the three prevalent cancers in the general population, and people involved in shift and night work are increasing all over the world. Ergonomic criteria concerning shift system organization less disruptive of the circadian system and more complying with the biological and social well-being should be duly considered.