The findings call for a global strategy emphasizing prevention, early detection, and tailored treatments for younger patients.

A recent study titled "Global trends in incidence, death, burden, and risk factors of early-onset cancer from 1990 to 2019," led by Dr. Jianhui Zhao from Zhejiang University School of Medicine in Hangzhou, China, has unveiled an alarming 79% surge in new cancer cases among individuals under the age of 50 worldwide over the past three decades (1990-2019). 

This research, published in late September in BMJ Oncology, sheds light on significant shifts in the landscape of early-onset cancer.

In 2019, breast cancer emerged as the leading cancer type among this age group.

However, the most substantial increases in incidence since 1990 were observed in cancers of the nasopharynx (windpipe) and prostate. Cancers causing the greatest mortality and health impact among younger adults in 2019 included breast cancer, windpipe cancer, lung cancer, bowel cancer, and stomach cancer.

These findings challenge prevailing notions about the types of cancers typically affecting individuals under 50, as suggested in an associated editorial.

While cancer is traditionally associated with older age groups, evidence suggests that cases among those under 50 have been on the rise across many regions since the 1990s. Most prior studies focused on regional and national variations, neglecting the global perspective and risk factors specific to younger adults.

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To bridge these knowledge gaps, the researchers leveraged data from the Global Burden of Disease 2019 Study, encompassing 29 types of cancer in 204 countries and regions. They analyzed the incidence of new cases, mortality, disability-adjusted life years (DALYs), and contributing risk factors for individuals aged 14 to 49 to estimate the annual percentage change between 1990 and 2019.

Shifting cancer demographics

In 2019, there were 1.82 million new cancer diagnoses among those under 50, marking a 79% increase from the 1990 figure. Breast cancer accounted for the highest number of cases and associated deaths, with rates of 13.7 and 3.5 per 100,000 of the global population, respectively.

However, early-onset windpipe and prostate cancers witnessed the most rapid growth between 1990 and 2019, with estimated annual percentage changes of 2.28% and 2.23%, respectively. Conversely, early-onset liver cancer exhibited a decline of approximately 2.88% annually.

In 2019, over 1 million individuals under 50 succumbed to cancer, marking an almost 28% increase from 1990. Following breast cancer, the cancers with the highest mortality rates and subsequent health impact included windpipe cancer, lung cancer, stomach cancer, and bowel cancer, with the steepest increases in mortality observed in those with kidney or ovarian cancer.

High rates of early-onset cancers were observed in North America, Australasia, and Western Europe.

Nevertheless, low to middle-income countries were not spared, with the highest death rates among those under 50 occurring in Oceania, Eastern Europe, and Central Asia. Notably, in these countries, early-onset cancer had a more pronounced impact on women than men, both in terms of mortality and overall health.

Cancer set to further advance

Based on the trends observed over the past three decades, the researchers project a further 31% increase in the global number of new early-onset cancer cases and a 21% rise in associated deaths by 2030, with individuals in their 40s facing the highest risk.

Genetic factors are likely contributors to these trends, but the data highlight that diets rich in red meat and salt, low in fruits and dairy, alcohol consumption, and tobacco use are the primary risk factors for the most common cancers among those under 50.

Physical inactivity, excess weight, and high blood sugar are also contributing factors.

The researchers acknowledge several limitations in their findings, primarily stemming from the varying quality of cancer registry data across different countries, which may have led to underreporting and underdiagnosis. Additionally, the extent to which screening and early-life exposure to environmental factors influence these trends remains uncertain.

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Doctors from the Centre for Public Health at Queen's University Belfast emphasize in comments observed by ScienceDaily that a comprehensive understanding of the factors driving these trends remains elusive, although lifestyle factors are likely contributors. They also highlight emerging areas of research, including antibiotic usage, the gut microbiome, outdoor air pollution, and early-life exposures, as potential avenues for further exploration. 

“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. There is a pressing need for partnership, collaboration, and resource distribution at a global level in order to achieve these aims,” they stated.

The research was funded by the Natural Science Fund for Distinguished Young Scholars of Zhejiang Province and the National Nature Science Foundation of China.

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