Recent data suggest that the incidence of early-onset cancer, defined as cancer diagnosed in people younger than 50 years, is on the rise in several countries. Two recent studies confirm this trend, including one published in early September in BMJ Oncology that presents worldwide data on the matter.
Early-onset cancer
Among them, early-onset breast cancer had the highest incidence (13.7) and mortality (3.5 per 100k) rates in the global population.
Tracheal (nasopharyngeal) and prostate cancer have increased the most rapidly since 1990, with annual percentage changes estimated at 2.28% and 2.23%, respectively. At the other end of the scale, cases of early-onset liver cancer dropped by around 2.88% year on year.
Increase in deaths
There were more than a million (1.06) cancer deaths among patients younger than 50 years in 2019, which is an increase of slightly less than 28% compared with the figures from 1990.
The top four early-onset cancers with the highest mortality and disability-adjusted life year rates among young adults in 2019 were early-onset breast; tracheal, bronchus and lung; stomach; and colorectal cancers. The mortality rates of early-onset kidney cancer and ovarian cancer showed the fastest increasing trends.
“These results contrast with a more traditionally held view of ‘typical’ cancers in adults aged under 50 years,” Ashleigh C. Hamilton, MD, an academic clinical lecturer, and Helen G. Coleman, PhD, a professor, both at Queen’s University Belfast’s Centre for Public Health in the United Kingdom, explained in an accompanying editorial. An important aspect of this study is that it tackled the issue of increasing cancer rates among young people on a global scale, they added. Here, the researchers made use of 2019 data from the Global Burden of Disease database for 29 types of cancer in 204 countries and regions.
Industrialized countries
The highest rates of early-onset cancer in 2019 were reported in North America, Australasia, and Western Europe. However, the burden of early-onset cancers in low- to middle-income countries is also of major public health concern. The highest death rates among patients younger than 50 years were in Oceania, Eastern Europe, and Central Asia.
In low- or middle-income regions, early-onset cancer had a significantly higher impact on women than on men in terms of mortality and disease burden, the researchers reported.
On the basis of trends observed over the past 30 years, they estimate that the global incidence and deaths of early-onset cancer would increase by 31% and 21% in 2030, respectively, with 40-year-olds being the most affected.
Hypotheses and limitations
How can this increase in the incidence of cancer among patients younger than 50 years be explained? For the authors, genetic factors likely play a role. But 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 in patients under age 50 years. Physical inactivity, excess weight, and hyperglycemia were shown to be contributing factors.
The researchers recognized several limitations to their conclusions. First, the accuracy of Global Burden of Disease data was compromised by the quality of cancer registry data in different countries, which may have led to underreporting and underdiagnosis. Also, questions remain about how screening and early exposure to environmental factors can affect the observed trends.
For the authors of the editorial, “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.”
They concluded, “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.”
The authors added, “It is worth exploring whether early screening and prevention programs for early-onset cancer should be expanded to include individuals aged 40-44 and 45-49, but further systematic studies and randomized trials are necessary to make a definitive determination.”
Trend in the United States
Between 2010 and 2019, although the incidence of cancer dropped in people over age 50 years in the United States, a study published in JAMA Network Open in August showed that the standardized incidence rate of early-onset cancer increased overall. More specifically, the rate increased in women but decreased in men.
In 2019, most early-onset cancer cases involved breast cancer. Between 2010 and 2019, gastrointestinal cancers saw the fastest rise. And among gastrointestinal cancers, those whose incidence rate increased the most rapidly were those affecting the appendix, the intrahepatic bile ducts, and the pancreas.
This article was translated from the Medscape French Edition. A version of this article appeared on Medscape.com.