Study: Gen X, Millennials Have a Higher Risk of Developing These 17 Different Cancers

Younger generations seem to have a higher risk of developing 17 different types of cancer, according to a new study.

The research, published on August 1 in The Lancet Public Health, looked at incidence rates for 34 different cancers in people born between 1920 and 1990. The results showed that many of these cancers—including pancreatic, ovarian, and colorectal cancers—are becoming more prevalent in Generation X (Gen X) and millennials.¹

These findings are “somewhat shocking and a little disappointing to see,” Corinne Joshu, PhD, associate professor of cancer epidemiology at the Johns Hopkins Bloomberg School of Public Health, told Health.

This isn’t the first piece of research to come to this conclusion—in fact, a study published just last month predicted that Gen X will see higher rates of certain cancers as compared to their parents. Plus, other studies have called attention to concerning increases in early-onset cancer incidence, or cancer cases in people under age 50.²³

But this newly published study, led by researchers at the American Cancer Society, discovered that cancer prevalence isn’t the only concern—mortality rates also increased for multiple types of cancer in younger individuals, data showed.

“Despite many unknowns, emerging evidence suggests that early-lifetime exposures to well-established cancer risk factors, such as obesity, sedentary lifestyle, and unhealthy diet, increase the risk of early-onset cancers,” study author Hyuna Sung, PhD, a senior principal scientist and cancer epidemiologist at the American Cancer Society, told Health.

Younger People Are Seeing More Cancer Cases and Higher Mortality

To investigate how cancer was showing up differently across generations, Sung and her team looked at health records from the North American Association of Central Cancer Registries and the U.S. National Center for Health Statistics. They included data from over 23.6 million people who were diagnosed with one of 34 types of cancer. They also looked at records of over 7.3 million deaths from 25 different types of cancer.¹

The health records were from individuals aged 25 to 84 and were collected between January 2000 and December 2019.¹

The researchers divided the records based on birth year to compare cancer rates and mortality across five-year birth cohorts between 1920 and 1990. These birth cohorts helped the researchers control for social, economic, and environmental factors that might affect or explain cancer risk.¹

Overall, the study found that the incidence of eight of the 34 cancers increased with every successive birth cohort.¹

More specifically, the 1990 birth cohort had incidence rates two to three times higher than the 1955 birth cohort for pancreatic, kidney, and small intestinal cancer. This was also true for liver cancer in women.¹

The 17 cancers that had a higher incidence in younger people include:¹

• cardia gastric, a type of stomach cancer
• small intestine
• estrogen receptor-positive breast
• ovary
• colon and rectum
• leukemia
• endometrial and other cancers of the uterine corpus
• gallbladder and biliary tract
• kidney and renal pelvis
• pancreas
• myeloma (white blood cell)
• non-cardia gastric, a type of stomach cancer
• testicles
• liver and intrahepatic bile duct in women
• non-HPV-associated oral and pharynx in women
• anus in men
• Kaposi sarcoma (a cancer that causes lesions to grow throughout the body) in men⁴

However, not all trends were negative for younger people—the incidence rate and mortality of 14 different cancers either decreased or remained stagnant across birth cohorts. These included brain and nervous system cancer, cervical cancer, lung cancer, and more.¹

Despite the large amount of data that was included in the researchers’ analysis, Sung said there are further questions to explore. In particular, the researchers did not examine whether there were race-based differences in mortality or incidence trends, which warrants a follow-up study, she said.

However, this research provides a look at the many different cancer types that previous studies didn’t take into account and includes valuable information about younger generations’ risk of dying from cancer, said Sung. 

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Why Are Cancer Rates and Mortality Increasing?

For now, researchers don’t exactly know what’s behind the increase in cancer rates and mortality in younger generations.

One hypothesis is that cancer only seems more prevalent in younger people because doctors now have better tools to spot the signs of cancer early. However, Sung doesn’t think this explains the increase across birth cohorts.

“If there is an age-related difference, it would likely be more pronounced in older individuals as they tend to seek medical care more often,” she said. “Yet, the faster rise in cancer cases among younger adults and the disproportionate increase in this group cannot be fully attributed to advancements in diagnostics alone.”

Instead, exposure to carcinogenic (cancer-causing) environmental and lifestyle factors may be behind these increases.

“Ten of 17 cancers with [an] increasing trend are associated with excess body weight,” Sung said. “Other suspected risk factors include unhealthy diet, sedentary lifestyle, altered sleep patterns, and environmental chemicals, exposed during early life and young adulthood.”

In particular, more research is needed to understand the impacts of these environmental hazards—including microplastics—on people’s overall cancer risk, Sung said.

“The challenge now is to understand what part of these increases that we’re seeing is due to established, known risk factors, and exposure to those risk factors at younger and younger ages, and then how much of this is due to novel exposures,” Joshu added.

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Reducing Cancer Risk on an Individual and Systemic Level

While scientists aren’t sure yet what’s causing the increase in all of these cancers, there are well-known modifiable risk factors such as diet, sleep, and physical activity that can play a role in cancer risk, said Joshu.

Staying on top of regular screenings and addressing some of these risk factors are ways that individual people combat these trends.

“Maintaining a healthy lifestyle is not really that easy, and certainly not easy for everyone,” Joshu said. “I think as a society, we have to decide whether or not we value making a healthy lifestyle and healthy choices, the easy choices to make for everyone.”

But Sung also emphasized that positive health changes need to be promoted on a systemic level, too. These interventions can and should start young.

“Investing in education for health promotion, and improving the built environment and school food systems for children and adolescents [are] crucial to reducing the risk of cancer and other chronic diseases,” Sung said.

For kids, the importance of healthy school lunches, accessible spaces for physical activity, and education about how smoking and alcohol can affect our bodies “cannot be overstated,” she said.