Jet lag and liver cancer – what’s the story?

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.

Jet-setting mice

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.

Justine