Our Science Surgery series answers your cancer science questions.
Rich asked: Does cancer attack every age group?
Every two minutes someone in the UK is diagnosed with cancer. So whether it’s a friend, family member or your own diagnosis, cancer touches all of us, no matter how old.
But when it comes to who develops cancer, age plays a significant role.
“We see cases in every age group but many more cases in older people,” says Dr Katrina Brown, Cancer Research UK’s statistical information and risk manager.
“In the UK the highest rate of cancer cases is seen in the 85 to 89 age group,” says Brown. “Our risk of being diagnosed with cancer increases as we get older” she adds. And more than a third of all cancer cases in the UK are diagnosed in people aged 75 and over.
People under the age of 49 are much less likely to develop the disease, with only a tenth of cancer cases overall in the UK each year being diagnosed in people aged 25 to 49.
— Cancer Research UK (@CR_UK) July 12, 2019
These stats can largely be explained by biology. Cancer develops because of a build-up of DNA damage in genes that control how a cell grows. The older you are, the more your cells will have divided, increasing the chances that DNA errors will occur. As life goes on, you’re also exposed more to other factors that can damage your DNA, such as tobacco smoke and excess body weight.
And because cells are more likely to have more genetic faults as a person gets older, it’s more likely that some of these errors may lead to cancer.
Are some cancers more common in certain age groups?
Even though overall cancer is much more common in older people, there are three common cancer types that are more likely to diagnosed in younger people than older people.
The rates of people being diagnosed are highest at age 25 to 29 for cervical cancer, at age 30 to 34 for testicular cancer, and at age 0 to 4 for a type of blood cancer called acute lymphoblastic leukaemia. “But those are really the only common cancer types where the older age groups don’t have the main share of the cases,” says Brown.
Cervical cancer is more likely to be diagnosed around this age because virtually all cases are caused by the human papillomavirus (HPV), and exposure to this virus usually begins in adolescence. Cervical screening is offered to people with a cervix from the age of 25, which helps pick these cancers up at an early stage and also prevent future cases developing.
“For testicular cancer and acute lymphoblastic leukaemia, we are less clear why peak incidence rates are in younger people, because there’s limited evidence on the causes of these diseases,” says Brown.
Children’s cancers differ from adult cancers
The cancer types that children and young people are typically diagnosed with are different to those most common in adults. “The most common cancer types in children are leukaemias, lymphomas, tumours of the central nervous system and tumours in and around the brain” says Brown. But they are still rare. Each year around 160 children per million in the UK are diagnosed with any form of cancer. And biologically, these tumours can be quite different to those diagnosed in adults.
In fact, the number of cancer cases in children aged 0 to 14 and young people aged 15 to 24 each make up less than 1% of the total number of cancer cases diagnosed in the UK each year.
For almost every cancer type you look at, older adults are still the biggest contributor of cases.
– Dr Katrina Brown, Cancer Research UK
“For almost every cancer type you look at, older adults are still the biggest contributor of cases,” says Brown. And this is an important distinction to make. Brown says that one misconception she’s come across in her work is that leukaemia only affects children. “That’s absolutely not true,” she says.
Reducing cancer risk
Age is the biggest risk factor for cancer. And pinning down the causes in younger people can be hard. Some will have inherited faulty genes that increase their risk of developing particular types of cancer. While for others, it may just be bad luck.
We can’t always control random changes to our genes as we get older or those passed down the family line. But around 4 in 10 cancers are preventable, so there’s definitely a few things we can do to stack the odds in our favour. Not smoking and keeping a healthy weight are the best places to start.
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