Researchers have found that regular exercise could help prevent the most common type of liver cancer called hepatocellular carcinoma by activating a gene that suppresses tumour growth.
The study, published in the Journal of Hepatology, in an animal model provides strong evidence that voluntary exercise could help prevent the most common type of liver cancer, hepatocellular carcinoma, and identifies the molecular signalling pathways involved.
Fatty liver disease is common with obesity and diabetes and contributes to rapidly increasing rates of liver cancer throughout the world.
More than 800,000 people worldwide are diagnosed with this cancer each year. It is also a leading cause of cancer deaths, accounting globally for more than 700,000 deaths each year.
"Some population data suggest that persons who exercise regularly are less likely to develop liver cancer but, studies addressing whether this has a real biological basis, and, if so, identifying the molecular mechanism that produces such a protective effect, are few and the findings have been inconclusive," explained study lead investigator Geoffrey C Farrell from Australian National University in Australia.
Test subjects were obese and diabetic mice
For the findings, the research team studied whether exercise reduces the development of liver cancer in obese/diabetic mice.
Mice genetically driven to eat so that they become obese and develop type 2 diabetes as young adults were injected early in life with a low dose of a cancer-causing agent. Half of the mice were allowed regular access to a running wheel; the other half were not and remained sedentary.
The mice ran up to 40 kms a day as measured by rotations of the exercise wheel.
This slowed down the weight gain for three months, but at the end of six months of experiments, even the exercising mice were obese. At six months, most of the sedentary mice had liver cancer while none of the exercising mice had developed it.
This research shows that exercise can stop the development of liver cancer in mice that have fatty liver disease related to obesity and type 2 diabetes.
Specifically, while nearly all obese mice injected with a low dose of a cancer-causing agent developed liver cancer within six months, mice that regularly exercised failed to do so.
They were completely protected against liver cancer development in the timeframe of these experiments. Weight control did not mitigate the development of liver cancer.
Exercise has already been shown to improve some outcomes for patients with cirrhosis.
"If the present studies in an animal model that closely resembles humans with fatty liver disease can be replicated in patients, it is likely that exercise could delay the onset of liver cancer and mitigate its severity, if not completely prevent it - thereby greatly improving patient outcomes," Farrell added.