THE key to cancer prevention may lie in an ageing immune system rather than genetics, according to researchers.

Researchers from Dundee University, Heriot Watt University, Edinburgh University and the Institut Curie in France, found a declining immune system with age may be a stronger reason for developing cancer.

Men are more likely than women to be diagnosed and the chance of developing the disease rises dramatically with age. Genetic predisposition, lifestyle or environmental factors can all cause cancer.

Researchers analysed the data on two million cancer cases over the 18-70 age range and developed a mathematical equation for how they would expect cancer incidence to rise.

They discovered their model fitted the data better than the multiple mutation hypothesis.

The immune system, researchers found, generally declines slower in women than men allowing them to account for gender differences in cancer incidence.

Thea Newman, formerly vice principal of research and professor of biophysics and systems biology at the University of Dundee, said: “This is still very early days but if we are proven right then you could be talking about a whole new way to treat and prevent cancer.

“Nearly all of the mainstream research into cancer is based on how we can understand genetic mutations, target them and thereby cure the disease.

“We’re not debating the fact that mutations cause cancer, but are asking whether mutations alone can account for the rapid rise in cancer incidence with age when ageing causes other profound changes in the body.”

The team tested their model on data from the US-based National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) programme.

The results showed many cancers appear to be strongly linked to the decline of the immune system, while others are linked to a combination of immune system decline and multiple mutations.

Professor Clare Blackburn, an expert in thymus biology at the University of Edinburgh, added: “We believe that our findings are extremely relevant and show the need to take the immune system even more seriously in cancer research.

“In addition to mutations, this suggests we should also focus on how to boost thymus function in a controlled way.”

The research, has been published in the latest edition of the Proceedings of the National Academy of Sciences.