A cancer diagnosis is perhaps one of the most challenging events that can occur within your lifetime, but the varying forms of the disease that might strike depend very much on your age.
Research from Cancer Research UK shows that a third of all cancers are diagnosed in the over-75s, but the type of cancers that impact us in old age tend to affect different organs and have very different underlying causes compared to the ones that strike people in their youth.
“People who carry a particular genetic mutation tend to develop cancers much earlier in their life, and it’s much more aggressive, while cancers which affect people over the age of 75 are related to the ageing of our cells and the cumulative effect of lifestyle-related damage over the course of a lifetime,” says Dr Carla Perna, a clinical oncologist in Surrey.
Oncologists explain that the particular cell types in which cancer develops can also greatly vary with age. To give an extreme example, Dr Stephen Ansell, deputy director of Mayo Clinic Cancer Center in Rochester, Minnesota, says that childhood cancers often occur in cell types that are still developing, such as stem cells.
However, in old age, one of the most common forms of cancer is adenocarcinoma, which develops in cells located in the glands that line your organs.
“This is a broad generalisation,” says Ansell. “Adenocarcinomas occur because your glands are increasingly stimulated over time as you age, and that makes them at risk of mistakes happening during cell division which lead to cancer.”
So how does the risk of various cancers change with age? Let’s take a look at three different life stages.
25-49
When you’re young, you tend to assume that you’ll live forever, but research shows that more and more young adults are developing cancer. According to Cancer Research UK, rates increased by 22 per cent between the early 1990s and 2018.
In young men, one of the biggest contributors is testicular cancer, for which the average age of onset is just 33. “The best way to pick it up early is really through monthly self-examination,” says Dr Saif Ahmad, Academic Consultant Oncologist at the University of Cambridge and Addenbrooke’s Hospital, Cambridge. “These tumours are usually not that well rounded, so you’d be feeling a hard and irregular-shaped lump. But anybody who feels any kind of lump should go see their doctor.”
The main risk factors for this cancer are either a family history of the disease, or testicles which are still inside the abdomen and have not descended into the scrotum, a condition known as cryptorchidism which can be fixed through surgery.
Head and neck cancers and cervical cancer in women are also among the most common forms in this age group, due to the strong link with sexually transmitted strains of human papillomavirus (HPV). These strains cause damage to cells in the throat and cervix, which can ultimately induce cancer. Ahmad says that regular cervical screening and having the HPV vaccine in early adolescence are the best forms of prevention, particularly against multiple strains.
Women under 40 who develop breast cancer are more likely to have a particularly aggressive form of the disease known as triple negative breast cancer. This is strongly linked to an inherited mutation in the BRCA1 gene.
“If there’s a family history of breast cancer, women should start checking for lumps around 25, 30,” says Perna. “If they notice anything concerning, they don’t need to have a mammogram. For a young woman, a simple ultrasound is sufficient to pick up any problems.”
Bowel cancer rates are also rising among young adults for reasons which are unknown, although possible risk factors include a high intake of processed meats, alcohol, a sedentary lifestyle, and rising rates of obesity. In 2020, the US National Cancer Institute listed bowel cancer as the deadliest form of cancer in men under 50, as well as the third deadliest among women in the same age group.
Melanoma is also one of the most common cancers diagnosed in young adults, particularly women. “If you have a new mole or something shows up in your skin, I would advise that you really should have that checked out,” says Ansell. “Particularly if there’s a change in the colour or the size or the consistency of those spots, it’s very important that you have a good skin assessment. And then just wearing sunscreen and reducing the amount of blistering sunburns you get could be very beneficial.”
50-74
Both men and women experience major hormonal shifts during middle age, which can trigger vulnerability to various cancers.
Women who begin menopause late, after the age of 55, are markedly more at risk of endometrial, ovarian and breast cancer because they have been exposed to more estrogen which causes increased cell production, a risk factor for cancer. Likewise, post-menopausal women who are overweight in their fifties and sixties are also more at risk of these cancers because the body can derive estrogen from body fat.
Overweight men in this age group are also more susceptible to aggressive prostate cancers, as the excess layers of fat around the prostate act as a source of nutrients for growing cancer cells. Researchers at Imperial College London have estimated that if the average 55- to 64-year-old male in the UK reduced their body mass index to within the ideal range of 18.5 to 24.9, there would be 1300 fewer prostate cancer deaths per year.
Ahmad explains that there are a range of tests available to men and women in this age range, from mammograms to the CA125 blood test for ovarian cancer.
Lung cancer also starts to become more common during midlife, comprising 12 per cent of cancer cases in men aged 50-74 and 13 per cent of cases in women within that age range.
The Royal Marsden Hospital recommends that all over 50s who either smoke or gave up in the last 15 years should have a private annual low-dose CT scan to screen for lung cancer.
However, Perna points out that there is still a limit to what scans can pick up, so the best option is to quit smoking as soon as possible. “You can only spot big tumours on those scans, and you can’t really spot small tumours,” she says. “So not smoking is still the best form of prevention of all.”
75 and older
While cancer diagnoses in general become more common with age, this is not true for every form of the disease.
Oncologists say the cancers that develop after the age of 75 tend to be heavily linked to accumulated DNA damage over the course of a lifetime, sometimes as a result of poor lifestyle habits.
In men, bladder and prostate diagnoses are very common, while breast cancer still comprises 21 per cent of female cancer diagnoses in the over-75s. Lung and bowel cancer remain highly prevalent as well.
“With lung cancer, if you’ve been a smoker, a lot of carcinogens have been breathed in on a regular basis,” says Ansell. “With bladder cancers, there can be various substances that you’re urinating out, which can cause long-term irritation of the bladder lining, putting you at risk. We have a lot to learn about bowel cancer, but dietary habits over the course of a lifetime may ultimately make a difference.”
Ansell says that anyone with a history of bowel cancer in their family should consider getting a colonoscopy. Various tests are also available for bladder cancer, a disease which men are three to four times more likely to develop than women, for reasons that remain unknown.
Anyone concerned due to family history or worrying symptoms such as urine in their blood can get an investigation called a flexible cystoscopy which involves local anaesthetic and inserting a thin tube through the urethra to examine the bladder lining.
Overall, on the bright side, one of the few advantages of getting older is that if you’re diagnosed with any form of cancer, it’s likely to be less aggressive. Perna points out that one of the reasons why the NHS Breast Screening Programme stops at 70 is because any woman diagnosed with breast cancer in later life is more likely to have a slower-growing form of the disease.
“All of your cells are less active, your metabolism is slower and therefore even the cancer cells have a more different time to grow because there are fewer demands for them,” says Perna. “But the most aggressive cancers are usually linked to genetic mutations, which mean they come earlier in life. So if you’ve reached 75 or 80, you’re much less likely to have a very aggressive disease.”