Harmful work
Working the night shift increased the risk of developing cancer
Maria Krivochenko, Naked Science
A group of researchers from the University of Washington found out how the work schedule affects the risk of developing cancer, and checked what role the biological clock plays in this. Details of the work are published in the Journal of Pineal Research (Koritala et al., Night shift schedule causes circadian dysregulation of DNA repair genes and elevated DNA damage in humans).
The team conducted an experiment. Biologists selected 14 adult and physically healthy volunteers. They spent seven days in the university laboratory: half of them "worked" in the night shift, and the other half – in the daytime.
After completing the simulated shifts, all participants were subjected to a protocol that is used to study the internal biological rhythms of people regardless of any external influences. As part of the protocol, they were not allowed to sleep for 24 hours in a reclining position with constant light and room temperature, and they were given the same snacks every hour. A blood sample was taken from them every three hours.
Analyses of white blood cells taken from the samples showed that the rhythms of many cancer-related genes were different in those who were awake during the night shift. In addition, leukocytes isolated from the blood of night shift participants showed more signs of DNA damage. In addition, they were more vulnerable to external damage from radiation – a risk factor for DNA damage and cancer development.
The results also showed that night shifts disrupt the natural 24-hour cycles of activity of some genes associated with cancer. This makes night shift workers more vulnerable to DNA damage. "Night shift workers face problems ranging from high risk of metabolic and cardiovascular diseases to mental disorders and cancer. Our task is to find new methods of diagnosis and treatment of this group of people," he added The co-author of the study is Professor Hans van Dongen.
The scientists noted that additional research is to be carried out. Their next step is to repeat the same experiment with people who, in reality, have been constantly working day or night shifts for many years, and determine whether they accumulate DNA damage over time. If what happens to these workers is consistent with the findings obtained during the experiment, the study can be used to develop prevention and treatment strategies that could solve the problems of night shift workers.
In addition, they will help optimize the timing of cancer treatment and make sure that the effectiveness of therapy is higher and side effects are minimal. The procedure, called chronotherapy, according to scientists, should be precisely tuned to the internal rhythms of night workers.
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