Constant Global Rise in Early-onset Cancer in Under 50s

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Early-onset Cancer

Sometimes, early-onset cancers are classified as cancer wherein age 39 is >1 standard deviation below the mean age of diagnosis for that cancer type, and young-adult cancer was defined as cancer wherein age 39 is <1 standard deviation below the mean age at cancer diagnosis. Although the percentages are small, incidences are increasing in some of the deadliest cancers usually found in older adults, such as colorectal, lung, breast, pancreatic, and multiple myeloma. The rising rates of obesity in the United States may be a critical contributing factor to this trend - the current prevalence of obesity is about 19% among children and adolescents between the ages of 2 and 19; 40% among adults between the ages of 20 and 39; 45% among adults between the ages of 40 and 59; and 43% among adults aged 60 and older and going up in all adult age groups. However, obesity alone does not fully explain the rise in early-onset cancers, especially colorectal cancer, in younger people. Other risk factors, such as smoking, diet, the microbiome, and lack of access to high-quality health care and screening, also contribute to the development of early-onset cancers in this population.

Main Digest

Is early-onset cancer an emerging global epidemic?

Current evidence and future implications Over recent decades, more and more adults under 50 have been developing cancer. A study conducted by researchers from Brigham and Women's Hospital reveals that the incidence of early onset cancers (those diagnosed before age 50), including cancers of the breast, colon, esophagus, kidney, liver, and pancreas, among others, has dramatically increased around the world, with this drastic rise beginning around 1990. To understand why many younger individuals are being diagnosed with cancer, scientists conducted extensive analyses of available data in the literature and online, including information on early life exposures that might have contributed to this trend. Results are published in Nature Reviews Clinical Oncology.

"From our data, we observed something called the birth cohort effect. This effect shows that each successive group of people born at a later time (e.g., decade-later) have a higher risk of developing cancer later in life, likely due to risk factors they were exposed to at a young age," explained Shuji Ogino, MD, Ph.D., a professor and physician-scientist in the Department of Pathology at the Brigham. "We found that this risk is increasing with each generation. For instance, people born in 1960 experienced higher cancer risk before they turned 50 than those born in 1950, and we predict this risk level will continue to climb in successive generations."

To conduct this study, Ogino and lead author Tomotaka Ugai, MD, Ph.D., also of the Department of Pathology, and their colleagues first analyzed global data describing the incidence of 14 different cancer types that showed increased incidence in adults before age 50 from 2000 to 2012. Then, the team searched for available studies that examined trends of possible risk factors, including early life exposures in the general population. Finally, the team examined the literature describing clinical and biological tumor characteristics of early-onset cancers compared to later-onset cancers diagnosed after age 50.

In an extensive review, the team found that the early life exposome, which encompasses one's diet, lifestyle, weight, environmental exposures, and microbiome, has changed substantially in the last several decades. Thus, they hypothesized that factors like the westernized diet and lifestyle might contribute to the early-onset cancer epidemic. The team acknowledged that this increased incidence of certain cancer types is partly due to early detection through cancer screening programs. They couldn't precisely measure what proportion of this growing prevalence could solely be attributed to screening and early detection. However, they noted that the increased incidence of many of the 14 cancer types is unlikely solely due to enhanced screening alone.

Possible risk factors for early-onset cancer included alcohol consumption, sleep deprivation, smoking, obesity, and eating highly processed foods. Surprisingly, researchers found that while adult sleep duration hasn't drastically changed over several decades, children are getting far less sleep today than they were decades ago. Risk factors such as highly processed, sugary beverages, obesity, type 2 diabetes, sedentary lifestyle, and alcohol consumption have increased significantly since the 1950s, which researchers speculate has accompanied an altered microbiome.

"Among the 14 cancer types on the rise that we studied, eight were related to the digestive system. The food we eat feeds the microorganisms in our gut," said Ugai. "Diet directly affects microbiome composition, and eventually these changes can influence disease risk and outcomes."

One limitation of this study is that researchers did not have adequate data from low- and middle-income countries to identify trends in cancer incidence over the decades. In the future, Ogino and Ugai hope to continue this research by collecting more data and collaborating with international research institutes to monitor global trends better. They also explained the importance of conducting longitudinal cohort studies with parental consent to include young children who may be followed up for several decades.

"Without such studies, it's difficult to identify what someone having cancer now did decades ago or when one was a child," explained Ugai, "Because of this challenge, we aim to run more longitudinal cohort studies in the future where we follow the same cohort of participants throughout their lives, collecting health data, potentially from electronic health records, and biospecimen at set time points. This is not only more cost-effective considering the many cancer types that need to be studied, but I believe it will yield more accurate insights into cancer risk for generations to come."

Funding:

The work of S.O. is supported in part by the U.S. National Institutes of Health grants (R35 CA197735 and R01 CA248857) and the Cancer Research UK Cancer Grand Challenge Award [6340201/A27140]. The work of T.U. is supported by grants from the Prevent Cancer Foundation, Japan Society for the Promotion of Science, and Mishima Kaiun Memorial Foundation.

Paper cited:

Ugai T et al. "Is early-onset cancer an emerging global epidemic? Current evidence and future implications." Nature Reviews Clinical Oncology

Attribution/Source(s):

This peer reviewed article relating to our Cancer and Tumors section was selected for publishing by the editors of Disabled World due to its likely interest to our disability community readers. Though the content may have been edited for style, clarity, or length, the article "Constant Global Rise in Early-onset Cancer in Under 50s" was originally written by Brigham and Women's Hospital, and published by Disabled-World.com on 2022/09/06 (Updated: 2023/01/04). Should you require further information or clarification, Brigham and Women's Hospital can be contacted at massgeneralbrigham.org. Disabled World makes no warranties or representations in connection therewith.

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