A new study published in the open-access journal BMJ Oncology reveals a staggering 79 percent increase in the number of new cancer cases among individuals under the age of 50 worldwide over the past three decades (1990-2019).
In 2019, breast cancer accounted for the highest number of "early onset" cases in this age group. However, cancers of the windpipe (nasopharynx) and prostate have seen the most significant increases since 1990, according to the analysis.
The cancers that had the most significant impact on younger adults' health and mortality in 2019 were breast, windpipe, lung, bowel, and stomach cancers.
The findings challenge the conventional understanding of the types of cancer that typically affect those under 50, according to a related editorial.
While cancer is more common in older individuals, evidence suggests that cases among those under 50 have been on the rise in many parts of the world since the 1990s. However, most studies have focused on regional and national differences, with few examining the issue from a global perspective or assessing risk factors for younger adults.
To address these knowledge gaps, researchers utilized data from the Global Burden of Disease 2019 Study, covering 29 cancers in 204 countries and regions. They examined the incidence (new cases), deaths, health consequences (disability-adjusted life years or DALYs), and contributory risk factors for individuals aged 14 to 49 to estimate the annual percentage change between 1990 and 2019.
In 2019, there were 1.82 million new cancer diagnoses among those under 50, representing a 79% increase compared to 1990 figures. Breast cancer accounted for the largest number of these cases and associated deaths, at 13.7 and 3.5 per 100,000 of the global population, respectively.
However, new cases of early-onset windpipe and prostate cancers increased the fastest between 1990 and 2019, with estimated annual percentage changes of 2.28% and 2.23%, respectively. Conversely, early-onset liver cancer decreased by an estimated 2.88% each year.
In 2019, over 1 million (1.06 million) individuals under 50 died of cancer, marking an almost 28% increase from 1990 figures. After breast cancer, the cancers with the highest death toll and subsequent health issues were windpipe, lung, stomach, and bowel cancers, with the sharpest increases in deaths observed in individuals with kidney or ovarian cancer.
The highest rates of early-onset cancers in 2019 were found in North America, Australasia, and Western Europe. However, low to middle-income countries were also affected, with the highest death rates among those under 50 in Oceania, Eastern Europe, and Central Asia.
In low to middle-income countries, early-onset cancer had a more significant impact on women than on men in terms of both deaths and subsequent health issues.
Based on observed trends over the past three decades, 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 those in their 40s being most at risk.
Genetic factors are likely to play a role, but the data indicate that diets high in red meat and salt, low in fruit and milk, alcohol consumption, and tobacco use are the main risk factors for the most common cancers among those under 50. Physical inactivity, excess weight, and high blood sugar are contributory factors.
The researchers acknowledge limitations to their findings, primarily the variable quality of cancer registry data in different countries, which may have led to under-reporting and under-diagnosis. It's also unclear to what extent screening and early-life exposure to environmental factors may be influencing the observed trends.
Doctors from the Centre for Public Health at Queen's University Belfast emphasize that "the findings challenge perceptions of the type of cancer diagnosed in younger age groups." They emphasize the urgent need for prevention and early detection measures, along with identifying optimal treatment strategies for early-onset cancers, taking into account the unique supportive care needs of younger patients.
In conclusion, they stress the need for a global partnership, collaboration, and resource distribution to achieve these aims.