Last updated February 6, 2018 at 10:56 am
Do genetic mutations alone account for the rapid rise in cancer incidence with age?
Most anti-cancer efforts across the world focus on genetic mutations as the cause, but age-related increases in cancer risk may actually be linked to the immune system, according to a new study.
For decades it has been known that mutations arising as a result of genetic predisposition or lifestyle and environmental factors cause cancer and that the chance of developing most cancers rises dramatically with age.
The traditional view is that the way cancer incidence increases with age could be understood and quantified if multiple (typically five to six) mutations in one cell are required to initiate cancer.
A mathematical model
However, the research team from the University of Dundee, Heriot Watt University, the University of Edinburgh and the Institut Curie in France, has shown that the declining immune system with age may actually be a stronger reason for the increasing incidence of developing cancer than multiple mutations.
Following the hypothesis that an aging immune system may result in higher rates of cancer, just as it leads to older people being more prone to other diseases, the team looked at data on two million cases of cancer in people aged 18-70.
They then developed a mathematical equation for how they would expect cancer incidence to rise in relation to a declining immune system and compared it to the age profiles for 100 different cancers.
Their model fitted the data better than the multiple mutation hypothesis. Because the immune system generally declines more slowly in women than men, they were also able to account for the gender difference in cancer incidence, something that mutations alone cannot easily explain.
Implications for cancer prevention
This suggests that the immune system, particularly as it declines, may play a far bigger role in the development of cancer than previously thought. If borne out by further studies, this could have significant implications for cancer prevention and treatment across the globe.
“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,” said senior author Dr Thea Newman, formerly Vice Principal of Research and Professor of Biophysics and Systems Biology at Dundee.
“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 study was published in the Proceedings of the National Academy of Sciences.