Cancer cases among the under 50s have soared by 79% globally over the past three decades, reveals new research.
Breast cancer accounted for the highest number of ‘early onset’ cases in 2019, say scientists.
But cancers of the windpipe and prostate have risen the fastest since 1990 while liver cancer cases saw the biggest fall, according to the findings published by BMJ Oncology.
Cancers exacting the heaviest death toll and compromising health the most among younger adults in 2019 were those of the breast, windpipe, lung, bowel, and stomach.
And researchers forecast that the trend will continue with those in their 40s the most at risk.
While cancer tends to be more common in older people, the evidence suggests that cases among the under 50s have been rising in many parts of the world since the 1990s.
But most previous studies have focused on regional and national differences while few have looked at the issue from a global perspective or the risk factors for younger adults.
The research team looked at data from the Global Burden of Disease 2019 Study for 29 cancers in 204 countries and regions.
They analysed new cases, deaths, health consequences and contributory risk factors for all those aged 14 to 49 to estimate annual percentage change between 1990 and 2019.
In 2019, new cancer diagnoses among the under 50s totalled 3.26 million, an increase of 79% on the 1990 figure.
Overall, breast cancer accounted for the largest number of cases and associated deaths at 13.7 and 3.5/100,000 of the global population, respectively.
But new cases of early onset windpipe and prostate cancers rose the fastest between 1990 and 2019, with estimated annual changes of 2.28% and 2.23%, respectively.
Early onset liver cancer saw the biggest fall of an estimated 2.88% every year.
‘More than one million under 50s died of cancer in 2019, an increase of just under 28% on the 1990 figure,’ said the study’s author Dr Xue Li, of Edinburgh University.
‘After cancer of the breast, cancers exacting the highest death toll and subsequent poor health were those of the windpipe, lung, stomach, and bowel, with the steepest increases in deaths among people with kidney or ovarian cancer.’
The highest rates of early onset cancers in 2019 were in North America, Australasia, and Western Europe.
Low to middle income countries were also affected, with the highest death rates among the under 50s in Oceania, Eastern Europe, and Central Asia.
In low to middle income countries, early onset cancer had a much greater impact on women than on men, in terms of both deaths and subsequent poor health.
Based on trends over the past three decades, the researchers estimate that the global number of new early onset cancer cases and associated deaths will rise by a further 31% and 21%, respectively, in 2030, with those in their 40s the most at risk.
Genetic factors are likely to have a role, say the researchers.
‘Diets high in red meat and salt, and low in fruit and milk; alcohol consumption; and tobacco use are the main risk factors underlying the most common cancers among the under 50s, with physical inactivity, excess weight, and high blood sugar contributory factors, the data indicate,’ said Dr Li.
The researchers said it’s still not clear to what extent screening and early life exposure to environmental factors may be influencing the observed trends.
Medics from the Centre for Public Health, Queen’s University Belfast, said the findings ‘challenge perceptions’ of the type of cancer diagnosed in younger age groups.
‘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,’ said Dr Ashleigh Hamilton.
‘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.’
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