Gastrointestinal Cancer Cases Increasing Among Younger Population

Early-onset cancer is a diagnosis that occurs between the ages of 18 and 49. According to a new review published in JAMA, early-onset gastrointestinal cancers are drastically on the rise.  

Tiago Biachi, MD, PhD, a gastrointestinal oncologist at Moffitt Cancer Center, says that several factors likely contribute to this trend.  

Potential Contributing Factors 

• Lifestyle: obesity, poor diet, eating processed foods, eating red meat, drinking sweetened beverages  

• Environmental and early life exposures: toxins, hormones, dietary patterns 

• Gut microbiome changes: poor diet, antibiotic use, exposure to microplastics 

“When it comes to gut microbiome changes specifically, research indicates that younger patients with colorectal cancer have less diverse microbiomes compared to older patients,” Biachi said. “However, the exact mechanisms linking microbiome changes to cancer remain unclear.” 

Colorectal and gastroesophageal cancers in young adults are believed to be closely connected to someone’s lifestyle and diet.

Tiago Biachi, MD, PhD

Researchers analyzing data from 2022 found that colorectal cancer was the most common gastrointestinal cancer seen in patients under 50, followed by gastric cancer.  

According to the American Cancer Society, the rate of colorectal cancer cases in those younger than 50 increased by 2.4% each year from 2012 to 2021.  

 “Colorectal and gastroesophageal cancers in young adults are believed to be closely connected to someone’s lifestyle and diet,” Biachi said.  

When it comes to screening guidelines for colorectal cancer, average-risk adults are recommended to start screening at age 45. There are no screening guidelines for gastroesophageal cancer (cancers of the esophagus and stomach) and pancreatic cancer for the general population.  

Challenges With Early Detection  

• Lack of awareness (due to an old mindset that these cancers should be seen later in life) 

• Lack of screening resources  

• Nonspecific symptoms  

“Along with the lack of screening guidelines for certain GI cancers, symptoms can be very nonspecific, which is why listening to the body is very important and any persistent GI symptoms must be addressed,” Biachi explained.  

Furthermore, researchers found that 15% to 30% of early-onset gastrointestinal cancer cases have hereditary genetic mutations. These gene mutations can predispose an individual to developing certain types of cancer.  

“Germline testing is recommended for all colorectal cancer patients under the age of 50,” Biachi said. “It is also recommended for all patients with pancreatic cancer, regardless of age, and for any patient with a suspicious inherited condition. This test can be performed using a patient’s blood or saliva and identifies mutations in normal cells (not in cancer cells).” 

Genetic testing can help determine the most effective treatment option for patients and indicate whether additional cancer screenings are necessary.  

Early-onset gastrointestinal cancers are among the largest subset of early-onset cancers globally.

This JAMA Review summarizes current evidence on early-onset gastrointestinal cancers. https://t.co/Za5LnjpWyE @KimmieNgMD @DanaFarber pic.twitter.com/00snxmPaxH

— JAMA (@JAMA_current) July 17, 2025