Why are so many younger people getting cancer?

Australia Broadcast Center

07-07-2025

Sydney Pead: Cancer has traditionally been a disease of old age, but younger Australians in their 30s and 40s are increasingly being diagnosed with cancer and scientists are desperate to understand why. Today, Dr Norman Swan on his Four Corners investigation into what could be causing the sharp rise in cancer rates among younger people and what can be done about it. I'm Sydney Pead, on Gadigal land in Sydney, this is ABC News Daily.
Sydney Pead: Norman, you've been looking into the alarming increase in cancer rates in younger people. As a millennial, I'm pretty personally invested in this story. It's pretty concerning. So what kind of increase are we seeing here?
Norman Swan: It varies according to cancer. So a lot of publicity has been about bowel cancer, but in fact, the data given to Four Corners by Cancer Australia shows 10 cancers rising in the under 50s. It's called early onset cancer, but it's particularly marked in 30 to 39 year olds. If you take the statistics from 2000 to 2024, bowel cancer has gone up 173%, prostate cancer in this age group 500%, pancreatic cancer 200%, liver cancer 150%, kidney cancer 85%. Breast cancer is going up, but at a lower rate than the others.
Sydney Pead: Oh my goodness, that is such a worry. And you've actually been talking to people who have been diagnosed with cancer at a relatively young age. Can you tell me a bit about Fiona?
Norman Swan: Fiona So trained in accounting and finance. She's got three kids and her and her husband live in Sydney. And she was diagnosed eventually after about six months of odd symptoms, which were not ignored.
Fiona So, cancer patient: I started getting like itch all over my body. And we thought it might be an allergy. We did blood tests, everything. And you don't think liver cancer would happen to someone who's like just turned 40.
Norman Swan: By the time they actually investigated that, she had a huge liver tumour, which ruptured before it could be operated on. I mean, really quite dramatic.
Fiona So, cancer patient: You straight away think, why me? What have I done? I don't smoke. I don't drink. I wasn't obese. I didn't have any of those symptoms. You know, I was being healthy. I was living, trying to, you know, do all the right things and it still happens.
Sydney Pead: Mm, absolutely. It's so shocking, really. So in Fiona's case, what did her treatment plan look like?
Norman Swan: Fiona had major surgery to remove the tumour and part of her liver. Unfortunately, not long after the surgery, it was clear that the cancer had spread, partly because it had ruptured. And now she's on a clinical trial of another treatment. And that is keeping things under control. But sadly, it's not a cure. I mean, this is hugely traumatic for her, her three kids and her husband, David.
Fiona So, cancer patient: The first thought I had was, I'm not going to watch them grow up. I'm not going to see them go to university. And it's not something you ever thought. You thought you get to grow old with your husband. You get to watch your kids grow up. And then suddenly that was something that could be taken away from you.
Sydney Pead: And Norman, sadly, this situation that Fiona finds herself in, it's becoming more common in young people who are juggling work commitments and family and medical appointments. So I want to turn now to some of the causes that might account for this spike in cancer rates, because we hear so many things. Is it air pollution or microplastics or too many meat cold cuts? You've been speaking to Dan Buchanan, who is one expert. He looks at bowel cancer and he says changes in our gut are a big concern.
Norman Swan: What Dan Buchanan has found, and he studies what's called oncogenomics. This is the pattern of DNA mutations that you see in cancers. He can pretty much tell the age of somebody with bowel cancer from the genetic mutations in their bowel tumour. In other words, there's been a generational change. So older Australians who get bowel cancer and you look at their genetic mutation pattern, there was a change with Gen X and then with millennials. So something has happened. And he believes that that something is related to the microbiome, the guts.
Associate Professor Dan Buchanan, bowel cancer researcher: We have lots of bacteria in our gut, and it's that balance between good and bad bacteria that creates a healthy state. So we think that exposures or environmental toxins may change that balance between good and bad bacteria, allowing some not so friendly bacteria to produce toxins or agents that may damage our DNA.
Norman Swan: What he and others have found in a proportion of people, it looks as though early in life they were infected with a bug called E. coli. Now we've got lots of E. coli in our bowels and there's lots of different forms, but this was a toxic form of E. coli. And the toxin, the chemical that it produced, damaged the bowel and changed the DNA in the bowel, leading to bowel cancer in some people. The reality is cancer causation is a slow process. You get multiple mutations over time and it's unusual for that to gallop. Most of the time it's a fairly steady and slow process that can take 10, 20, 30 years. So if you're getting cancer when you're 30 or 40, you've got to go back to your childhood or your mum's pregnancy. That's likely when the changes occurred. So for example, if you look at the microbiome, caesarean section rates were going up during that time to quite high levels. And when you're born by caesarean section, at least for the first few months, you don't have a normal microbiome. When you're born vaginally, you ingest the microbiome of your mum. It doesn't happen when you're born by caesarean section. Antibiotic use in kids wasn't going up particularly at that time, but antibiotics certainly were being used. That was round about the time when ultra-processed foods started booming. So that makes your microbiome vulnerable. We also found in the course of researching the Four Corners in 1975, which looked as if it was made last week, because it talks about plastics, plastic ingestion and toxins in plastic that might be the source of cancer. And why hadn't we banned them?
Four Corners 1975: Today, when they sell us our daily bread, it comes in a plastic bag. Now it emerges that when we eat food packed in plastic, we might unknowingly be eating some of the plastic as well. And no one knows the effects of that.
Norman Swan: Microplastics are a possible cause, again, with no proof at this point. But they do get mashed down to very tiny, almost molecular sizes, which then can penetrate into our bloodstream and cause inflammation, maybe affect our brains and our heart, maybe related to cancer. We just don't know.
Sydney Pead: So concerning. Let's just stay on this topic of microplastics, because that is such a big concern. And unfortunately, plastic is something that's virtually impossible to avoid. So many of us get our takeaways in plastic containers or heat up leftovers in plastic in the microwave. So can we blame plastic for rising cancer rates?
Norman Swan: The answer is we don't know. I spoke to Dr Christos Symeonides, who works for the Minderoo Foundation. He's a paediatrician and he studies chemical and plastics. And he argues that this is an area that we don't really like to confront.
Dr Christos Symeonides, Paediatrician: We're exposed to a broad universe of synthetic chemicals that our biology isn't familiar with. And that has left a great deal of uncertainty. Within the universe of plastic chemicals, we're looking at the last academic count at about 16,000 chemicals that are used or present in plastics.
Norman Swan: When you look at the chemicals in plastics, there are thousands and thousands of chemicals, only a few of which have actually been properly studied for their hazards in humans.
Dr Christos Symeonides, Paediatrician: Of those 16,000 chemicals, only one third appear to have been evaluated for potential hazard. If we look back at that one third that have been evaluated, the substantial majority, around 75%, are identified to be hazardous from those assessments. But there's a limit to which that tells us about what they'll do in our full, complex biology of the human body.
Norman Swan: But we assume that the ones that haven't been tested are safe and we allow them to be used, but they might not be.
Sydney Pead: Yeah, that's right. And as you say, it's not a new problem. We've been talking about this even here at the ABC since 1975. Just a little more on that. What have we learned about these plastics and the other chemicals that we're exposed to in our environment because PFAS, for example, is just a huge concern.
Norman Swan: With PFAS, the so-called forever chemicals, which are in non-stick frying pans, they're in cosmetics, they're in a lot of different products. They do persist and when they persist, you do worry about their long-term effects. There's a lot of doubt about whether they as a group do cause cancer. There's not a huge amount of evidence for that. There is one called PFOA, which is just being regulated for and banned for industrial use in Australia, but that's linked to kidney cancer and probably breast cancer as well. Now, it may be that some of the others are, but yet to be proven.
Sydney Pead: So, Norman, for young Australians, these numbers are so worrying. Yes, we can throw away our plastic utensils or our non-stick frying pans or avoid bacon, but it's going to take a lot more than that. So does the government have a long-term strategy to tackle these increasing cancer numbers?
Norman Swan: We still really haven't got an anticipatory strategy for chemicals anywhere in the world, really, not just Australia. And there's something called the precautionary principle. We talked about that a lot during COVID. The precautionary principle is if something looks as though it's causing a problem or could be causing a problem and there's no harm in removing it, then you should remove it. Or you should not introduce it until it's proven to be safe. In other words, you should not wait until a hazard has been found. And the problem here is 30-year-olds today could well be paying the price of things that happened 30 years ago in the environment, and we only find the hazards out when it's too late.
Sydney Pead: So in the meantime, is there a stopgap solution like expanding the age range of cancer screening programs to catch these diagnoses earlier? Because too often these diagnoses are coming really late for younger patients.
Norman Swan: First thing to say is we only screen for four cancers. Cervical cancer screening, which starts at the age of 25. Breast cancer screening, which starts at 50, despite the fact that 20% of breast cancers and probably a growing percentage occur in people who are under 50. Bowel cancer screening, which starts at the age of 50, but it's moved down to 45. But again, you've got to opt in rather than you automatically being in the screening program. And then finally, there's lung cancer, and that's for heavy smokers, either current heavy smokers or past heavy smokers with no symptoms. Now the thing with screening is screening is of a healthy population with no symptoms. You do not want a screening program to make people sick or worse. Cancer is still a disease of aging. The older you are, the more likely there is to be damage to your DNA, and you're more likely to have cancer. Therefore, in a screening program, if you are older and you find an abnormality, that abnormality is more likely to be serious than it is if you're young, despite this increase. And therefore, you're discovering in a screening program, more people who have abnormalities that may not matter or may not turn into cancer. But the risk is that people have invasive investigations and sometimes invasive treatments, which they might not have needed. So you've got to work that one out. Then it's a question of economics for government. Can they afford to make these screening programs younger? It's likely to save lives, but there are economic costs involved. The main strategy that's left is early detection of people with symptoms. In addition to us all doing what we know does work for a lot of cancers, which is a decent amount of physical activity, a Mediterranean-style diet, where you're eating a lot of different vegetables, not eating a lot of red meat, and certainly not smoking burnt plants, whatever plants they may be, whether it's cannabis or tobacco.
Sydney Pead: So certainly being made aware of the symptoms and to know what to be on the lookout for is going to be a huge part of this.
Norman Swan: I have maybe three messages here. One is get yourself a general practitioner that you like, who gets to know you. A lot of younger people don't have a GP. It's important to find a GP and a practice. And sometimes that's a bit of a search to find a GP who's right for you. The second thing is, if something new happens to you, you've never had before, a headache, a lump, bleeding, bruising, anything virtually that you've just never had before, don't sit on it. Go and see your GP. Probably nothing, but it might not be. And thirdly, don't let it go. If it hasn't gone away, if it comes back, go back. It's your body and be assertive.
Sydney Pead: Dr Norman Swan is a reporter for ABC's Four Corners and host of the Health Report podcast. You can watch Norman's Four Corners report on ABC iView. This episode was produced by Kara Jensen-McKinnon. Audio production by Sam Dunn. Our supervising producer is David Coady. I'm Sydney Pead. ABC News Daily will be back again tomorrow. Thanks for listening.