Repeated jet lag may increase liver cancer risk

Repeated jet lag can increase both obesity related liver disease and the risk of liver cancer, researchers warned. "Liver cancer is on the rise worldwide, and in human studies we have now seen that patients can progress from fatty liver disease to liver cancer without any middle steps such as cirrhosis," said lead author David Moore, Professor at Baylor College of Medicine in the US.

The study found that chronically jet-lagged mice developed liver cancer in a very similar way as that described for obese humans. When we constantly travel through different time zones, work night shifts, or push ourselves to stay awake at the regular sleep time, our central circadian clock in the brain becomes chronically disrupted, the researchers said.

"We think most people would be surprised to hear that chronic jet lag was sufficient to induce liver cancer," Moore added. In the study, the researchers changed the times the lights went on and off during the night each week to understand the effects of chronic jet lag in normal mice who were fed a healthy diet.

They found that the mice gained weight and fat, and developed fatty liver disease, which progressed to chronic inflammation and eventually liver cancer in some cases. The jetlagged mice lost normal control of liver metabolism. This included not only the buildup of fat, but also increased production of bile acids acids produced by the liver to help us digest our food linked with liver cancer.

Further, the jetlagged mice were also lacking in receptors called FXR and CAR that help regulate liver bile acid metabolism, which works in a similar manner in humans. Although the researchers did not directly study jetlag in humans.

But as evidence have showed that sleep disruption increases both fatty liver disease and liver cancer risk in humans, they hypothesised that lifestyle changes that generate chronic jet lag can also disrupt the body's internal homeostasis and increase liver cancer risk in humans. The study appears in the journal Cancer Cell.