If we’re to stop the rise in under 50s getting cancer, things need to change

A disturbing generational shift appears to be underway in the rates of cancer in people in their 30s and 40s.

Cancers that have always been far more prevalent in older people are now affecting younger people in higher and higher rates. This increased risk is likely to follow them for the rest of their lives.

So what do we do about it?

Remember during COVID how we talked about bending the curve? Well, this trend is going to be a very hard one to bend.

But it’s not a hopeless task. There are ways to change the steep cancer trajectories that generation X and millennials might be on. They include screening at younger ages, earlier detection and possibly most importantly of all, more assertive preventive strategies by governments and regulators.

Age counts in cancer

To understand what we can do, it helps to have a clearer idea of the new challenges we’re facing.

What hasn’t changed is that increasing age is still the major risk factor for cancer.

The older you are, the more likely you are to develop cancer.

That’s thought to be due to the time needed for the multiple genetic mutations which transform a healthy cell into a malignant one. So, in crude numbers, most people with cancer are older.

What has changed is a dizzying and scary increase in the rates of cancer in the under 50s. It’s happening in at least 10 different types of cancer.

You can see the rise in figures provided to Four Corners by Cancer Australia.

It’s not just Australia. US research using large datasets found rises in about half the cancers they record in their cancer registries.

The actual numbers of young people with cancer are still low relative to older people, but they’re unlikely to stay low. The upward trajectory we’re hoping to bend will likely rise inexorably as gen X and millennials age (more research on millennials is needed, but the signs are there).

It’s because of what’s called the cohort effect. If researchers are right, the rise in younger adults will get worse as it’s compounded by the effects of aging.

One of the US’s leading cancer bio-statisticians, Philip Rosenberg, says what he’s seeing is “astonishing”.

“If things stay on their current trajectories, then we can expect that they would continue to experience those proportionate increases as they get older.”

He says rates of cancer for people born in the 70s could be double those born in the 50s.

The other disturbing feature of some of these early-onset cancers is that they tend to be diagnosed at a later stage than tumours diagnosed in older people. That means they’re more likely to have invaded the surrounding tissues and spread, leading to more surgery, chemotherapy and radiation therapy, and ultimately poorer outcomes.

This puts more urgency on doing something to bend the trajectory downwards to stop or slow this inexorable rise.

The reasons these cancers are being diagnosed at a late stage aren’t clear. One possibility is people and their doctors not thinking that certain symptoms such as lumps, discomfort or bleeding could be cancer when someone is young and as a result delaying appropriate tests.

Professor Jon Emery who studies cancer in general practice at the University of Melbourne, isn’t so sure that’s happening — at least in bowel cancer. He’s studied time to diagnosis in Victorian general practices in people over and under 50 and found no delays in younger adults.

Another and chilling reason may be that early-onset tumours are not the same as cancers in older people. They may be more aggressive to start with. Anecdotally, there are people who haven’t delayed their diagnosis, yet have advanced cancer from the get-go. If this is true, then it has enormous implications for bending the trend.

Screening

How can we find these cancers in young people earlier?

One way is to reduce the age of cancer screening.

The national bowel cancer screening program, in response to the rise in early-onset cancers, now starts at age 45 instead of 50. But is that early enough especially since between 45 and 49 you have actually got to ask or agree to participate?

The breast screening program still only begins at 50 despite 20 per cent of breast cancers being detected in women under 50. Women between 40 and 49 can have free screening mammograms but again they have to ask to participate.

A significant percentage of lung cancer these days occurs in people who’ve never smoked, particularly women. And while the data can be hard to dissect, organisations such as the Lung Foundation believe the rates in younger “never smokers” are rising. But the lung cancer screening programme, which has just begun, is only for present and past heavy smokers aged between 50 and 70.

Given the trends in early-onset cancers, shouldn’t we be doing a lot better?

“Well, we don’t lower the age of screening because it’s not that simple,” says Dorothy Keefe of Cancer Australia, who herself is an oncologist. “It has to be safe and effective.”

What Professor Keefe is referring to is the risk of unnecessary tests and invasive treatments — weighing up the harms against benefits.

That’s because screening isn’t diagnosis. It’s about finding abnormalities in healthy people who have no symptoms. These abnormalities might not be cancerous or never turn out to be malignant.

At a minimum, a person with an abnormality will undergo a further diagnostic test like a colonoscopy or biopsy.

Even with the rise in early-onset cancers, these abnormalities found during screening are more likely to be cancer in older people than younger ones. And even once you’ve done a biopsy and it looks cancerous, there’s no guarantee with some of these lesions that they’ll turn into cancer.

Increasing, screening can mean younger people are subjected to invasive tests and even treatments that they might not have ever needed.

It could also mean longer public waiting lists for colonoscopies due to increased demand.

In the end though, changing screening programs is about governments deciding on the cost and resource availability.

And even if screening was expanded to younger ages, the bottom line is that at the moment only four cancers are screened for. Those are bowel, breast, cervix and lung.

One reason we don’t screen for all cancers is that you need simple, cost-effective, reliable tests to determine who needs further testing and who doesn’t. That technology doesn’t exist yet for most cancers.

Another reason is that detecting cancers earlier doesn’t always make a difference to the outcome. With some cancers diagnosing early could just mean you spend more years with the knowledge that you have cancer, being subjected to treatments with side effects that could have been as effective later in the course of the disease. So the end point is the same. That may be true, say, of ovarian cancer.

With those limitations, it still means that something needs to be done for the broad range of cancers on the rise. For that, what we’re left with at the moment is to do better with people who have developed symptoms. Are we doing enough to catch cancer early enough once it’s causing problems? That puts the onus on health professionals such as GPs.

Earlier diagnosis

If you have symptoms, the process is entirely different from screening healthy people. It’s about targeted diagnosis, often with blood tests, imaging and biopsies.

“The people that you talk to, the young people with cancer, they actually do have symptoms,” Professor Keefe argues.

“One of the problems is that they have symptoms that aren’t easily recognised because of their young age as being associated with cancer.”

The first stop that most of us have (after Google) when we have an unexplained symptom is our general practitioner. Could GPs be making diagnoses sooner?

Professor Jon Emery studies the diagnosis and treatment of people with cancer in general practice — or primary care. He argues that GPs face a needle in a haystack problem with early-onset cancers.

“Diagnosing cancer in general practice is challenging,” he says.

“If we think about a change in bowel habit, which is a common symptom of bowel cancer. Let’s say there are a hundred people over 50 who come to see their GP with a change in bowel habit, about three to four of those will actually have bowel cancer. If you’re over 70, it’ll be about six (in a hundred).

“But in under 50-year-olds, a hundred people presenting to their GP with a change in bowel habit, less than one of those will actually have a bowel cancer. So that’s part of the challenge.”

Dr Emery thinks one answer is a process he calls safety netting. It’s about all of us getting better at recognising symptoms that we should see our GP about without delay. Bleeding and symptoms you’ve never had before are examples.

It also involves doctors making use of the simple tests they do have if they’re uncertain there’s an issue, having follow up checks, and ensuring the patient knows to come back if the symptom doesn’t go away or returns.

“It never should be said that someone is too young to have cancer,” Professor Keefe says.

“What we need to do is make sure that everybody to whom a patient might present has knowledge of what symptoms are red flags and what symptoms should trigger some sort of investigation.”

Dr Emery is also working on using artificial intelligence to analyse complex patterns of symptoms in someone’s history to raise red flags across a number of cancer types that GPs might not have otherwise noticed.

In the near future, blood tests which can measure cancer markers and make detection easier may be shown to be accurate and usable in the population at large.

We assume that early detection will bend the curve downwards but can’t be certain.

All this adds up to prevention strategies being essential.

Prevention

To prevent cancer you really want to know what’s caused it — and when. Sure, we can put the responsibility for this onto individuals — not smoking burnt plants, eating more veg, keeping our weight down and getting the recommended amount of physical activity.

That will likely make a difference to cancers that are strongly lifestyle in origin like uterine and liver, but our lifestyle has been pretty lousy for a long time and the causes of early-onset cancers may be beyond individual control.

Given cancer can take decades to develop, decades in a 30-year-old takes you back to early childhood or even your mum’s pregnancy.

One theory is that back then, something happened to mothers’ and kids’ microbiomes — the bugs in their bowels. Eating ultra-processed foods, antibiotic use, and increased caesarean births (where babies don’t acquire the normal microbiome) potentially made our guts more vulnerable to dangerous bacteria.

Then there’s damage from chemicals all those years ago, which might only be emerging today.

“We have a blind spot around environmental chemicals and cancer,” says Christos Symeonides, a paediatrician who works with the Minderoo Foundation on the health effects of chemical and plastic exposures.

And it’s a big blind spot with micro and nano plastics in our food and drinking water, and persistent chemicals like PFAS in products like cosmetics, non-stick frying pans and stain resistant fabrics. Much is still unknown, and there’s little transparency.

While some chemicals have been restricted or banned, there are still thousands that haven’t been properly assessed for their health impacts — and that’s just those used in plastics.

“We would want to have a system where we know what we’re exposed to,” argues Dr Symeonides.”Right now, I have a deep interest in plastics and the chemicals in certain plastics, but I can’t tell you what chemicals have been used in any plastic that you show me and the brand that produced that plastic product. They also don’t know which chemicals are sitting in the plastic that they use to make their product.”

Dr Symeonides says that given the potential impacts are irreversible, governments and regulators shouldn’t be waiting for conclusive proof to mitigate the risks.

“The precautionary principle indicates that where you do have uncertainty and where, the potential impacts are irreversible or serious, then that could be grounds for acting before you wait for conclusive evidence of harm.”

These concerns aren’t new.

In the course of researching this issue we found a Four Corners from 1975 which ironically sounded the alarm about toxins in plastics, particularly PVCs which were known to be hazardous and persistent.

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It’s hard to avoid the conclusion that today’s 30 and 40-year-olds could be paying the price for slow regulation many years ago.

These are difficult issues. But do we really want to be asking in 40 years’ time when today’s kids are adults, whether we could have done more to prevent cancer in their generation?

Watch Four Corners’ full investigation, Generation Cancer, on ABC iview.

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