101 Facts About Ageing #14: The Biggest Risk Factor For Cancer Is Age

As Daniel Patrick Moynihan, an American sociologist, politician, and diplomat once said: “Everyone is entitled to his own opinion, but not his own facts”. And we wholeheartedly agree. A shared set of facts is the first step to building a better world with longevity for all. In that spirit, we are creating a series that covers 101 indisputable facts about ageing, health and longevity.

The most important risk factor for cancer is not genetics, diet or even smoking, but age. According to the National Cancer Institute (NCI), the median age for cancer diagnosis in the United States is 66 years, meaning that half of all cancers are diagnosed in those aged 66 or above. Cancer incidence is stochastic (random) – the probability of cancer occurring is determined by a range of genetic and environmental factors, but cannot be predicted precisely because it is the result of an inherently random process (genetic mutation).

There is no single explanation for why ageing increases the risk of cancer. Cancer is ultimately the result of random mutations within the DNA, which become more probable with age for a variety of reasons, while the body’s safeguards against mutation and cancer weaken. Cancer is also rarely the result of a single mutation within the genetic code. Rather, a series of mutations accumulating over the course of a lifetime are needed for a cancer to occur. The relationship between cancer and old age can therefore be partly explained simply by the fact that most cancers take a long time to develop.