Many are fit and outwardly healthy, prompting a scramble among scientists to establish what is causing the trend.
One study that looked at data from Northern Ireland between 1993 and 2019 found the rate of early-onset cancers increased by 20.5 per cent, the equivalent of about 7000 extra cases a year across the UK.
These cancers include those that come under the umbrella term “abdominal”.
Professor Andrew Beggs, a consultant colorectal surgeon and a senior clinical fellow at the University of Birmingham, runs a clinic for cancer patients under 45.
“When I started as a cancer surgeon 20 years ago, you rarely saw any younger patients, but now I see them regularly,” he said.
“When they turn up they are shocked, because often they haven’t had any symptoms and, because of their age, they are not thinking about cancer.”
“It’s a huge thing to get your head ‘round at that age, and of course, many have young children,” he added. “My thoughts are with Kate and her family. It must have hit them like a bus.”
There is significant confusion among researchers as to what might be causing the trend, although most agree it is unlikely to be down to a single factor. Some scientists believe the cause may be partly genetic.
Catherine, Princess of Wales, revealed her cancer diagnosis and announced she is undergoing chemotherapy in a video message released on Friday. The announcement came after weeks of speculation spread across social media about her whereabouts and health since she was hospitalised in January for unspecified abdominal surgery. Photo / Kensington Palace
Roughly one in 100 people carry the BRCA gene – made famous by Angelina Jolie – which causes breast and ovarian cancers, while roughly one in 350 are affected by Lynch syndrome, a hereditary cause of bowel, womb, ovary and pancreatic cancers.
Researchers are also beginning to turn their sights on possible changes to the microbiome to explain the trend.
The composition of gut bacteria – as a result of dietary or other environmental factors – can influence inflammation levels, which in turn may increase the risk of cancer.
However, despite growing theoretical enthusiasm, scientists are hindered by the difficulty in conducting the necessary long-term cause-and-effect studies needed to draw a link between what people eat and their risk of the disease.
Dr Shivan Sivakumar, an associate professor in oncology at the University of Birmingham, agreed with Beggs: “There is an epidemic currently of young people [under 50] getting cancer.”
“It is unknown, the cause of this, but we are seeing more patients getting abdominal cancers.”
Doctors and scientists are scrambling to establish what is causing the rise in abdominal cancers among people under 45. Photo / Getty Images
Models based on global data predict the number of early-onset cancer cases will increase by around 30 per cent between 2019 and 2030, a markedly faster increase than the previous 30 years.
Cancer Research UK is among prominent research funding bodies across the world supporting programmes to better understand early-onset cancer.
Michelle Mitchell, its chief executive, said: “High-profile cancer cases often act as a prompt to encourage people to find out more or think about their own health.”
“If people spot something that’s not normal for them or isn’t going away, they should check with their GP.
“It probably won’t be cancer. But if it is, spotting it at an early stage means treatment is more likely to be successful.”
