So what does the evidence say is causing this increase? And what can we do about it?
Why does cancer mostly affect older people?
Each cell in your body contains a copy of your DNA – the instructions needed to keep that cell functioning properly.
However, DNA can be damaged or “mutated” in such a way that a cell will no longer do the job it’s supposed to.
Some mutations will allow a cell to make too many copies of itself and grow out of control. Others can protect it from dying. And others still allow it to and travel to other organs where it doesn’t belong.
Accumulating too many of these DNA mutations can lead to cancer.
Every time a new cell is made in our body, a copy of our DNA is made too. Sometimes, due to random chance, mistakes occur which introduce genetic mutations.
Think of it like making a photocopy of a photocopy, and so on. Each copy will be slightly different than the original.
Most DNA mutations are harmless.
But your cells are making billions of new copies of themselves each day. So the older you get, the more DNA copies you will have made during your lifetime, and the you are to have dangerous mistakes in those copies.
As we get older, our bodies aren’t as good at recognising and removing cells with dangerous mutations. That’s why cancer is .
What’s causing cancer in younger people?
One of the reasons increased cancer rates in younger people is so worrying is it means there are likely environmental factors involved .
Environmental factors are anything outside of our bodies: things such as chemicals, viruses and bacteria, the amount we exercise, and the foods we eat.
Many of these environmental factors can increase the likelihood of DNA copying mistakes, or even directly damage our DNA, increasing our risk of cancer.
One well-known example is ultraviolet (UV) radiation from the sun, which can lead to skin cancer. Another is smoking, which can lead to lung cancer.
Fortunately, public awareness campaigns about the dangers of sun exposure, and reduced rates of people smoking cigarettes, have led to of skin and lung cancer cases in Australians under 50 over the past 30 years.
But other types of cancer – including cancers of the liver, pancreas, prostate, breast and kidney – are in Australia. The trend is , particularly among richer, western countries.