Nine things you need to know about cancer surge among under-50s | Cancer

A global study published in BMJ Oncology this week reported a surge in the number of people under the age of 50 being diagnosed with cancer. Here are nine things everyone needs to know.

How rapidly is cancer rising among the under-50s?

The latest study reports that global cases of early onset cancer, defined as cases in those aged 14 to 49, increased by 79% between 1990 and 2019, from 1.82 million to 3.26 million.

The authors of the study, led by the University of Edinburgh and Zhejiang University School of Medicine in Hangzhou, China, have faced criticism for not reflecting population rises over the last three decades in their findings. “The world human population increased by 46% between 1990 and 2019, which explains part of the increase in total case numbers,” says Prof Dorothy Bennett, of St George’s, University of London.

However, even with population growth, experts agree that cancer in the under-50s is becoming more common. “Previous reports have shown that globally, since the 1990s, there has been an increase in cancer incidence rates in the under-50s,” says Prof Montserrat García-Closas, of the Institute of Cancer Research, London.

A similar study led by Harvard University, published in Nature in 2022, found that early onset cases were rising rapidly in 14 types of cancers.

Bar chart: worldwide cancer cases affecting the under-50s

Are more under-50s dying from cancer?

No. Cancer now kills 1 million under-50s a year. The latest study reported a 27.7% rise in deaths since 1990 – but with a larger population rise, this suggests a falling death rate.

Bennett says: “The increase in numbers of cancer deaths in this age group was notably lower than for diagnoses, namely 28%, which is below the increases in total population and case numbers, indicating a fall in the average cancer death rate in this group.”

García-Closas says this means “more people under 50 are surviving their cancers”, which is “likely due to improvements in early detection and treatments”.

What are the main types of cancers affecting under-50s?

The study found that almost one in five (18.83%) of the 3.26 million cases in 2019 were digestive system cancers, which include bowel, oesophageal, liver, pancreatic and stomach cancers.

That is interesting because in the earlier Harvard study, eight of the 14 cancer types increasing among the under-50s related to the digestive system.

Skin cancers formed the second largest group (17.16%) in the latest study, followed by breast cancer (16.50%).

What are the fastest-growing types of cancer among younger people?

Cancers of the windpipe (nasopharynx) and prostate have risen the fastest since 1990, according to the latest study, which looked at data on 29 cancers in the under-50s from 204 countries.

Are there any differences in the data between men and women?

Yes. Breast cancer is the most common type among women, according to the latest study, while tracheal, bronchus and lung cancer has the greatest disease burden among men.

Why are cases of cancer rising among the under-50s?

That is the million-dollar question – and one that experts do not have the definitive answer to yet. The researchers behind the latest study said they were concerned that poor diet and lifestyle may be partly to blame. They suggested several factors were linked to early onset cancers, including excess weight, diets high in red meat and salt, low intake of fruit, physical inactivity, smoking and alcohol consumption. Genetic factors may also be playing a role.

The researchers behind the Harvard study drew similar conclusions. “The reasons for this phenomenon are not entirely clear but are probably related to changes in risk-factor exposures in early life and/or young adulthood from the mid-20th century onwards,” they wrote in Nature. “The increased consumption of highly processed or westernised foods together with changes in lifestyles, the environment, morbidities and other factors might all have contributed to such changes in exposures.”

Experts are trying to discover what lies behind the rise. “Full understanding of the reasons driving the observed trends remains elusive, although lifestyle factors are likely contributing, and novel areas of research such as antibiotic usage, the gut microbiome, outdoor air pollution and early life exposures are being explored,” wrote Ashleigh Hamilton and Helen Coleman, of Queen’s University Belfast, in an editorial linked to the BMJ Oncology study.

What about global differences?

You might assume that wealthier countries have healthier people. But the highest rates of cancers among the under-50s were in North America, Oceania and western Europe, the study found.

The highest cancer death rates among younger adults were in Oceania, eastern Europe and central Asia. In low- and middle-income countries, early onset cancer had a much greater impact on women than on men, in terms of subsequent poor health and death.

How worried should people be?

About 90% of cancers still occur among people over the age of 50. Age remains a major non-modifiable risk factor for cancer. Therefore, if you’re in your 20s, 30s or 40s, it’s important to know that early onset cancer is still uncommon.

However, the uptick in cases among younger adults should still prompt action, experts say. “It is important to educate both the public and healthcare professionals regarding the possibility of certain cancers in younger adults to allow earlier diagnosis, which in turn improves outcomes,” wrote Hamilton and Coleman. “Prevention and early detection measures are urgently required, along with identifying optimal treatment strategies for early onset cancers, which should include a holistic approach addressing the unique supportive care needs of younger patients.”

Is there anything that can be done to reduce the risk?

Absolutely. Dr Claire Knight, a senior health information manager at Cancer Research UK, says: “If people are concerned about their cancer risk, there are lots of ways to help reduce this, such as not smoking, maintaining a balanced diet, getting plenty of exercise and staying safe in the sun.”