The International Agency for Research on Cancer (IARC) has for years maintained its decision to classify shift work, especially night work, within the group of “probable human carcinogens”.
In fact, there are more and more epidemiological studies that establish a direct relationship between shift work, especially the night shift, and the development of hormone-dependent tumors, such as those of the breast, prostate or colon.
Jet lag is also responsible for other health conditions, both physical and psychological, ranging from being more vulnerable to catching a cold or flu, to falling into states of depression, metabolic disorders and errors in the immune system.
“It is documented that shift workers are 40% more likely to have these tumors. It is clear that something is happening, but molecularly there is still much to describe”, the doctor explains to EFEsalut Antonia Tomás Loba
“What we want is to understand molecularly what happens in order to know the early events that can lead us to develop cancerous tumors, and then be able to talk about prevention.”
Head of the Circadian Rhythm and Cancer Group at the University of Murcia and member of the working group of Chronobiology of the Spanish Dream Society (SES)Tomás Loba leads a research (Cancer and Chronodisruption) with which he aims to demonstrate how
In this study, preliminary data of which have just been published, diurnal rodents were subjected to a protocol of jet lag socialwhich consisted of two weekends of going to bed and getting up later than usual.
With just two weekends of jet lag social, the molecular clock of the liver has been desynchronized and has been sufficient for the animals to show a liver with more accumulated fat (steatosis) and with important changes in their lipid and carbohydrate metabolism, especially in the former.
According to the researcher, they have also detected another important change in the cells of the immune system.
Thus and due to the protocol of jet lag social, in the organs of animals subjected to changes in the light pattern a change in the infiltration of immune cells has been observed.
“We don’t know if they enter and exit in a desynchronized way compared to control animals or if there is an error in the exit of these cells from the organ (cleaning) causing a pro-inflammatory state.”
Inflammation, he explains, is necessary since it arises from the activity of the cells of the immune system when eliminating harmful agents (viruses, bacteria, damaged tissue, etc.).
But when this inflammation becomes chronic as a result of ongoing damage, it can lead to early stages of cancer.
Shift work: the circadian system
“Our circadian system is flexible. It’s like a rubber band that you can stretch and then it returns to the starting point. However, if we stretch it a lot, it starts to give way and it no longer recovers its original shape.”
That is to say, that obviously nothing happens to go out two weekends in a row, because our liver is very plastic, very adaptable, it will recover immediately.
The consequences that have been seen in the liver of the study animals after two weekends of jet lag social media could be constantly passing through the livers of shift workers.
This, points out Tomás Loba, we still do not know for sure, because the relevant studies have not been done, but we are there.
The hepatic circadian system recovers, “but there comes a time when the tissue, cellular, molecular and circadian damage is so great that it is no longer reversible”, he concluded.
The researcher makes it clear that her study is with mice, but indicates that there is already epidemiological data that does indicate that shift work can lead to tumors because it is a possible carcinogen.
With their research, they aim to find out what happens to shift workers, what characterizes them, and how the internal clock, the one inside the body, and the external (the social) clock, if they are not aligned, can cause tumors or other diseases.
And Tomás Loba reiterates that there are already studies that indicate that working in tones would cause tumors, obesity, type 2 diabetes, neurodegenerative diseases, anxiety, depression….
“What we – he says – want, with animal models, is to try to understand molecularly what is not yet clear”.
In their laboratory they also have a line of research with the Verge de l’Arrixaca University Hospital with patients with hepatocarcinoma, to analyze what rhythms of life they lead, if they have been altered and how they influence their disease.
The study is carried out in people with early liver disease who arrive at the hospital with fatty liver, and looks at whether there is a match between their biological and social rhythms (internal clock/external clock) to see if they influence for worse or better in his illness, “because what interests us is to study to prevent”.