What's behind the latest headlines? Flickr/CC BY-NC 2.0
You may have seen some worrying headlines today suggesting that jet lag could cause liver cancer.
The reports followed a new study, published yesterday in the journal Cancer Cell, looking at the effects on the liver of disrupting the ‘body clock’ in mice.
So what did the research actually find? And is there cause for concern? We caught up with one of our liver cancer experts to dig into the details and answer these important questions.
Why were they studying this?
“Liver cancer rates are increasing, and undoubtedly modern lifestyle is the main reason behind this trend,” says Professor Derek Mann, one of our experts from the University of Newcastle.
“Our busy modern lives mean we’re eating later than we should, and we’re not sleeping at the right times. This disrupts our internal ‘body clock’, or circadian rhythm.”
Liver cancer rates are increasing, and undoubtedly modern lifestyle is the main reason behind this trend
– Professor Mann
And this circadian rhythm, which is ticking over in every cell of the body, is intimately linked to how cells make and process energy, says Mann. These processes – called cell metabolism – create energy by breaking down food, and the liver is heavily involved in this job.
When metabolism is disrupted, the liver can become fatty and stop working properly, leaving people at risk of further liver problems, of which cancer can be one.
So it looks like there could be close link between the body clock and metabolism by the liver, which is why the researchers, from Baylor College of Medicine in the US, decided to dig for details.
For their study, the team disrupted the circadian rhythm of mice in the lab by changing their exposure to light over prolonged periods, thus disrupting their sleeping patterns.
The idea was to mimic the effect of jet lag, where travelling causes people to be awake when their bodies are prepared for them to be sleeping and vice versa.
Compared to mice whose sleep wasn’t disturbed, the artificially ‘jet lagged’ mice gained weight, developed fatty livers and, in some cases, developed liver cancer.
On closer inspection, the team found that not only was the animals’ metabolism disrupted, but their livers were churning our more bile acids than normal.
“Bile acids are powerful chemicals that are important for the digestion of food and metabolism,” explains Mann.
“But we’re now finding that they’re also extremely important in the development of certain diseases.”
That’s why the researchers then looked at the effects of body clock disruption on mice without a molecule that helps regulate the levels of bile acids, called FXR.
Unsurprisingly, these mice had higher amounts of bile acids than normal. But they also developed more severe cases of liver cancer.
“That’s very interesting, because it suggests that the activity of FXR is protective against liver cancer,” says Mann.
What about us?
So what do these findings mean for people?
“This was a study carried out in mice under very strict conditions that don’t accurately mimic shift-work or jet lag,” Mann says.
“It’s a world away from humans. But from a biology perspective, the results are important.
It’s a world away from humans. But from a biology perspective, the results are important.
– Professor Mann
“That’s because there is actually a group of drugs being developed – one of which is in clinical trials for a specific liver disease – that protect the liver from damage by switching on FXR.
“So this study suggests that these drugs could have wider applications than we thought, and maybe one day could help protect against liver cancer in people at high risk of developing the disease.”
And although there is no hard evidence that shift work or staying up late at night causes liver cancer, Mann says, for him the message is simple.
“I think everybody needs to take a look at their lifestyle and be as healthy as they can. If you can avoid going to bed and eating at strange hours, then you can also avoid upsetting your body clock.”
So if this study has left you worried, there are things that you can do to lower your risk of developing liver cancer. According to Katie Edmunds, Cancer Research UK’s health information officer, “It’s important to remember that this particular study was carried out in mice, and there is no good evidence to suggest that jet lag increases the risk of liver cancer in humans.
“The best ways to reduce the risk of developing liver cancer are to be a non-smoker, keep a healthy weight, and cut down on how much alcohol you drink.”
So all in all, while the headlines may have painted a more bleak picture than deserved, there’s some interesting science here that warrants further study.
And for a cancer that can be hard to treat, finding a new avenue to pursue is an encouraging development.
Judy Owen February 10, 2017
My son is a long haul airline pilot who cannot avoid suffering from jet lag. The blog you mention is extremely worrying especially as it gives no definite link to humans. Do you really think that worrying people in this way will create extra revenue?
I have already lost my mother and my husband to cancer so the understanding of these awful illnesses is there engrained on my soul; I don’t need to be further upset to get me to support your charity.
Justine Alford February 13, 2017
We’re sorry to hear about your mother and husband, and that this article may have caused you to worry.
We wrote this article in response to headlines in the media and to clarify that the study was in mice, not humans. There is no good evidence that jet lag can cause liver cancer in people, but because long-term sleep disruption can cause certain health problems, it’s an area of research that scientists are looking into.
All the best,
Justine, Cancer Research UK
Kathryn Spurr February 2, 2017
It S interesting to note that any change to the circadian rhythm in the body could be a risk factor for liver cancer. I worked as a nurse for more than 2 decades working shifts in that time but had to take ill health rwtirement 21 yrs ago because of work associated back problems since which I have put weight on despite having a healthy lifestyle and drinking no more than the equivalent of a bottle of wine over a 7 day period. Because of my immobility I have become overweight in the years since finishing work. Because of this and my erratic sleep pattern due to the pain I am in 24hrs a day which means I sleep for noore than 4hrs a night, only falling asleep in the early hours of the morning it seems that I am at risk of developing liver cancer and I should like to know what else people such as myswlf can do to ameliorate that risk so further information about this would be gratefully received so that I can do something to improve the risk to me. I look forward to receiving further information from you.
Justine Alford February 7, 2017
We’re sorry to hear about the problems you’ve been having.
While some reports of this research may have made the results sound worrying, the study didn’t show that jet lag can cause liver cancer in people. At the moment it’s too early to tell whether this is the case, because the researchers looked at mice not people. The mice also had their sleep interrupted in a way that doesn’t accurately mimic jet lag in people, so it’s impossible to say whether the same effects will be found in people.
Currently there is no good evidence that jet lag or a lack of sleep is linked with the development of cancer in people and, recently, a large study concluded there’s no strong evidence that working night shifts can raise the risk of breast cancer in women. But Cancer Research UK continues to monitor new research in this area.
Although there is no guarantee against cancer, more than four in 10 cases could be prevented. You can read more about what people can do to help reduce the risk of cancer on our healthy living pages.
Heidi Coghlan February 2, 2017
Oh dear must re think I’m elderly go to bed 1 pm but do have 9 hours sleep.
David D Moore November 27, 2016
Thanks for a great summary of, and perspective on our work. I want to particularly credit the first author, Nicole Kettner and her mentor Loning Fu, who were primarily responsible for the story. And also to note that there actually is some direct evidence that sleep disorders are linked to increased risk for liver cancer:
This is the best study, but there are some others. It is certainly true that we only studied mice, but there is potential human relevance.