How obesity can shut off anti-cancer defences
Irish research has revealed people who are obese are more prone to cancer due to their weakened ability to destroy tumour cells.
The link between obesity and increased risk of cancer is well established, but Irish scientists have now thrown fresh light on the major health threat.
More than 300 cancer deaths a year are caused by being overweight or obese in this country.
The scientists in Trinity College Dublin examined the body's immune surveillance systems. This is where a person's immune system patrols the body to recognise and destroy host cells that become cancerous.
Potential cancer cells arise frequently throughout life, but the immune system usually destroys them as fast as they appear.
But they can operate differently in people who suffer from obesity and leave them with fewer defences to fight off cancer.
This is because fat-clogged cells do not have the energy to function at their optimum levels and this affects their ability to stop infected cells or tumours from growing.
The research has found possible ways the killer cells can be reprogrammed and jolted back in to action to ways they behave in a person of normal weight.
Nearly one-quarter of Irish people are now obese, increasing their chances of developing cancer.
Half of certain cancers are attributed to obesity. But until now, little had been known about the impact obesity has on immune surveillance.
The research was led by associate professor in immunology at Trinity College Lydia Lynch, who also conducts research at Harvard Medical School and Brigham and Women's Hospital in the US.
"Despite increased public awareness, the prevalence of obesity and related diseases continue," she said.
"Therefore, there is increased urgency to understand the pathways whereby obesity causes cancer and leads to other diseases, and to develop new strategies to prevent their progression.
"These cells are like marines in the army. They go in first, they're rapid and they are professional killers.
"They can be overcome and outnumbered but they're the first thing to detect a tumour and infected cells.
"So basically, obesity then causes more diseases and more severe diseases because these aren't working."
The new research, which has just been published in leading international journal 'Nature Immunology', shows overweight people are at a greater risk of developing cancerous cells, but experts now hope new treatments can be developed to inject energy into the cells in a process of "reprogramming" them.
"They say by 2030, nine out of 10 adults will be obese in Ireland.
"And there is such an increase in cases of cancer with obesity.
"That is why its such a scary problem," she added.
"And there are other things which we have no idea about the consequences yet - things like Alzheimer's and auto-immune diseases."
More than 1.9 billion people globally are classified as overweight and obese.