Cancer is increasing in people younger than 50, new study finds
A new study conducted by Boston researchers reveals that cases of early-onset cancers in adults under 50 years old have "dramatically increased" worldwide over the last few decades. This drastic rise began around 1990, and the risk appears to increase with each generation. People born in 1960, for example, have a higher risk of developing cancer before they turn 50 than those born in 1950.
Are doctors simply detecting more cancers now?
For the study, researchers analyzed global data on 14 cancer types, including; breast, colorectal (CRC), endometrial, esophageal, extrahepatic bile duct, gallbladder, head and neck, kidney, liver, bone marrow, pancreas, prostate, stomach, and thyroid cancer.
The results showed an increased incidence of all these cancers in adults before age 50 between the years 2000 to 2012.
"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," explains Shuji Ogino, MD, Ph.D., a professor and physician-scientist in the Department of Pathology at the Brigham.
To better understand, the team further searched for available studies that examined trends of possible risk factors, including early life exposures in the general population.
Finally, they examined the literature describing clinical and biological tumor characteristics of early-onset cancers compared to later-onset cancers diagnosed after age 50.
The extensive review concluded that factors like diet, lifestyle, environmental exposures, and microbiome had changed substantially over the past few decades, which may contribute to this early-onset cancer epidemic.
The team acknowledged that the rising incidence is partially attributable to early screenings for some cancers. However, they couldn't precisely measure what proportion of this growing prevalence could solely be attributed to screening and early detection. Therefore, more information is needed on individual exposures to confirm the cause.
The likely culprit?
Possible risk factors for early onset cancer include alcohol consumption, sleep deprivation, smoking, obesity, and eating processed foods which have all significantly increased since the 1950s. The study 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.
"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 Tomotaka Ugai MD, Ph.D., Department of Pathology Brigham. "Diet directly affects microbiome composition, and eventually, these changes can influence disease risk and outcomes."
The study is far from conclusive. Researchers didn't have much data from low- and middle-income countries to identify trends in cancer incidence over the decades. It's also imperative that future long-term studies include young children and track their health outcomes for at least a few decades.
In the future, the team will collect more data and collaborate with international research institutes to better monitor global trends. "Without such studies, it's difficult to identify what someone having cancer now did decades ago or when one was a child," says Ugai.
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