New research has shown that younger generations are at a higher risk for certain types of cancer. A study published in Lancet Public Health on Wednesday found that Gen X and Millennials have a higher likelihood of being diagnosed with 17 types of cancer, including nine that have been declining in older adults. Researchers are unsure of the exact cause, but factors such as obesity, more sedentary lifestyles, widespread medication use, and chemical exposures are all possible contributors.
New Cancer Trends
Hyuna Sung, a cancer epidemiologist at the American Cancer Society, led the research and stated, “What is happening in these generations can be considered a bellwether for future cancer trends.” Especially, colorectal cancer rates have been rising among younger people for decades, prompting further investigation into other types of cancer.
Sung and her colleagues analyzed cancer diagnosis and mortality data from two databases for individuals born between 1920 and 1990 who were diagnosed with cancer between 2000 and 2019. The data included 34 types of cancer, approximately 24 million diagnoses, and over 7 million deaths. To better understand how cancer diagnoses and mortality rates changed in groups of people born around the same time (called birth cohorts), the researchers grouped people by birth year in five-year intervals. For example, people born between 1920 and 1924 were considered one birth cohort.
Increasing Cancer Types
Among the 34 types of cancer, 17 showed increasing incidence in younger people. Those born in 1990 had a two to three times higher risk for pancreatic, kidney, and small intestine cancers compared to those born in 1955. Liver cancer diagnoses in women followed the same pattern.
Dr. Andrea Cercek, a gastrointestinal medical oncologist at the Memorial Sloan Kettering Cancer Center, who was not involved in the research, said, “The most important thing it tells us is there is something that changed for the group of individuals born after this period of time. They have been exposed to some environmental or lifestyle factor that is leading to this shift.”
Rising Cancer Types and Mortality
After decades of decline, these cancer types have started to rise again:
- Colorectal
- Endometrial
- Non-cardia gastric
- Gallbladder
- Ovarian
- Testicular
- Anal
- Estrogen-receptor positive breast cancers
- HIV-linked Kaposi sarcoma
The study found that while mortality rates for most cancers have declined or remained stable in younger generations, mortality rates increased among younger age groups for endometrial, intrahepatic bile duct, gallbladder, colorectal, and testicular cancers, as well as liver cancer in women. Endometrial cancer was the fastest growing in terms of both diagnoses and mortality.
Many cancer types remain rare among young people, and although the rates have increased, the overall number of cases is relatively low.
The Role of Obesity and Other Factors
The rise in these cancer types is largely attributed to the obesity epidemic. Dr. Otis Brawley, Professor of Oncology and Epidemiology at Johns Hopkins University, said, “All of these cancers are linked to the obesity epidemic. We know that’s the second-leading cause of cancer right now, behind tobacco use.” According to the American Cancer Society, about 20% of cancer diagnoses in the U.S. are linked to excess body weight.
Other Potential Causes
Obesity is only one of the possible causes. More sedentary lifestyles, something in the food or water supply, widespread medication use, or chemical exposures could also contribute to the rise. The overuse of antibiotics is another potential link under scrutiny, as antibiotics are known to alter the gut microbiome, which has been linked to colorectal cancer.
Conclusion
Researchers have yet to fully understand the reasons behind the increase in certain types of cancers among younger generations. While obesity and antibiotics are primary suspects, other chemical exposures or agents cannot be ruled out.
These findings regarding the rising cancer types among younger generations provide important insights for future health policies and prevention strategies. Better understanding the causes and risk factors of cancer is a crucial step in combating this disease.
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