The number of under-50s worldwide being diagnosed with cancer has risen by nearly 80% in three decades, according to the largest study of its kind, with more than 1m people in that age group dying of cancer every year.
Global cases of early onset cancer increased from 1.82 in 1990 to 3.26m in 2019, while cancer deaths of adults in their 40s, 30s or younger grew by 27%, the research reveals.
The Guardian reports that experts are still in the early stages of understanding the reasons behind the rise in cases.
The authors of the study, published in BMJ Oncology, said poor diets, alcohol and tobacco use, physical inactivity and obesity were probably among the factors, and that since 1990, the incidence and deaths of early onset cancers have substantially increased globally.
The latest study, led by the University of Edinburgh and Zhejiang University School of Medicine in Hangzhou, China, was the first of its kind to examine the issue on a global scale and the risk factors for younger adults.
Most of the previous research has focused on regional and national differences, but in this global study, researchers analysed data from 204 countries covering 29 types of cancer.
They looked at new cases, deaths, health consequences and contributory risk factors for people aged 14 to 49 to estimate changes between 1990 and 2019.
In 2019, new cancer diagnoses among under-50s totalled 3.26m, an increase of 79% on the 1990 figure. Breast cancer accounted for the largest number of cases and associated deaths, at 13.7 and 3.5 for every 100 000 of the global population respectively.
Cases of early onset windpipe and prostate cancers rose the fastest between 1990 and 2019, with estimated annual percentage changes of 2.28% and 2.23% respectively. At the other end of the spectrum, cases of early onset liver cancer fell by an estimated 2.88% a year.
A total of 1.06m under-50s died of cancer in 2019, an increase of 27% on the 1990 figure. After breast cancer, the highest death tolls were linked to windpipe, lung, stomach and bowel cancers.
The steepest increases in deaths were among people with kidney or ovarian cancer.
The highest rates of early onset cancers in 2019 were in North America, Oceania and western Europe. Low- and middle-income countries were also affected, and the highest death rates among under-50s 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 poor health and deaths.
Based on the observed trends for 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 by 2030, with people in their 40s the most at risk.
Genetic factors are likely to have a role, the researchers said. But diets high in red meat and salt and low in fruit and milk, along with alcohol and tobacco use, are the main risk factors underlying the most common cancers among under-50s, with physical inactivity, excess weight and high blood sugar contributory factors, the data indicate.
Dr Claire Knight, a senior health information manager at Cancer Research UK, which was not involved in the study, said it was not yet clear what was driving the trend and urged caution.
“However alarming this might seem, cancer is primarily a disease of older age, with the majority of new cancer cases worldwide being diagnosed in those aged 50 and above,” she said.
“We need more research to examine the causes of early onset cancer for specific cancer types, like our BCAN-RAY study that is looking at new ways to identify younger women at higher risk of breast cancer.”
Study details
Global trends in incidence, death, burden and risk factors of early-onset cancer from 1990 to 2019
Jianhui Zhao, Liying Xu, Malcolm Dunlop, Harry Campbell, Evropi Theodoratou et al.
Published in The BMJ Oncology Volume 2 Issue 1
Abstract
Objective
This study aimed to explore the global burden of early-onset cancer based on the Global Burden of Disease (GBD) 2019 study for 29 cancers worldwide.
Methods and analysis
Incidence, deaths, disability-adjusted life years (DALYs) and risk factors for 29 early-onset cancer groups were obtained from GBD.
Results
Global incidence of early-onset cancer increased by 79.1% and the number of early-onset cancer deaths increased by 27.7% between 1990 and 2019. Early-onset breast, tracheal, bronchus and lung, stomach and colorectal cancers showed the highest mortality and DALYs in 2019. Globally, the incidence rates of early-onset nasopharyngeal and prostate cancer showed the fastest increasing trend, whereas early-onset liver cancer showed the sharpest decrease. Early-onset colorectal cancers had high DALYs within the top five ranking for both men and women. High-middle and middle Sociodemographic Index (SDI) regions had the highest burden of early-onset cancer. The morbidity of early-onset cancer increased with the SDI, and the mortality rate decreased considerably when SDI increased from 0.7 to 1. The projections indicated that the global number of incidence and deaths of early-onset cancer would increase by 31% and 21% in 2030, respectively. Dietary risk factors (diet high in red meat, low in fruits, high in sodium and low in milk, etc), alcohol consumption and tobacco use are the main risk factors underlying early-onset cancers.
Conclusion
Early-onset cancer morbidity continues to increase worldwide with notable variances in mortality and DALYs between areas, countries, sex and cancer types. Encouraging a healthy lifestyle could reduce early-onset cancer disease burden.
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