A new study has found that globally, the rates of new cancer cases and associated deaths in people under 50 increased alarmingly between 1990 and 2019. The research highlights the importance of educating the public and healthcare professionals about the incidence of certain cancers in younger people.
Most previous studies have focused on regional and national variations in the incidence and death of all-age cancers, with only a handful examining ‘early-onset’ cancer, which is defined as cancer diagnosed from 14 to 49 years. However, that handful of studies has suggested that rates of cancer diagnosis in the under-50s is on the rise.
A new study led by Zhejiang University School of Medicine, the Harvard TH Chan School of Public Health, and the University of Edinburgh, has examined the global burden of early-onset cancer based on the Global Burden of Disease (GBD) 2019 study.
Using the GBD data, the researchers looked at new cases (incidence), number of deaths, health consequences (disability-adjusted life years, or DALYs) and risk factors for 29 types of cancer in 204 countries and regions.
They found that in 2019, new cancer diagnoses among the under-50s totaled 3.26 million, an increase of 79.1% on the 1990 GBD figure. The rate of early-onset cancer deaths increased by 27.7% between 1990 and 2019. All rates were calculated based on per 100k population, so ruled out population growth as the reason behind the trend.
Overall, breast cancer accounted for the largest number of cases and associated deaths, at 13.7 and 3.5 per 100,000 global population, respectively. But new cases of early-onset tracheal and prostate cancer rose the fastest, with estimated yearly percentage increases of 2.28% and 2.23%, respectively. Rates of early onset liver cancer fell by an estimated 2.88% every year.
North America, Australasia and Western Europe saw the highest rates of early-onset cancers in 2019. But low-to-middle-income countries were also affected, with the highest death rates among under-50s in Oceania, Eastern Europe, and Central Asia.
Based on these trends, the researchers estimate that, by 2030, the global number of new early-onset cancer diagnoses will rise by a further 31%, with associated deaths rising by 21%. They say those in their 40s are most at risk.
The data indicate that the main risk factors underlying the most common early-onset cancers are diets high in red meat and salt and low in fruit and milk, alcohol consumption and tobacco use. Physical activity, excess weight, and high blood sugar are contributory factors, and genetic factors are likely to play a part, too.
The researchers recognize that a limitation of the study is the variability of data collected by cancer registries in different countries and the difficulty in quantifying the completeness of the data. Thus, under-reporting and under-diagnosis in undeveloped countries may have resulted in an underestimation of the incidences and deaths of early-onset cancer.
An editorial accompanying the study pointed out that the role of inherited cases needs to investigated further.
“While most cases of early-onset cancer appear to be sporadic, the role of hereditary syndromes needs to be better quantified,” said the authors of the editorial, Ashleigh Hamilton and Helen Coleman, from the Center for Public Health at Queen’s University Belfast. “A major research gap is our limited understanding of the molecular pathogenesis of sporadic early-onset cancers, and whether certain subtypes are driving the increasing incidence.”
They say that the study’s findings highlight the importance of early diagnosis.
“The findings … challenge perceptions of the type of cancer diagnosed in younger age groups,” said Hamilton and Coleman. “It is important to educate both the public and healthcare professionals regarding the possibility of certain cancers in younger adults to allow earlier diagnosis, which in turn improves outcomes. 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 study and accompanying editorial were published in the journal BMJ Oncology.
