Cancer rates, particularly gastrointestinal cancers, continue to rise among young adults. (Photo by Frame Stock Footage on Shutterstock)
In A Nutshell
Americans born in 1990 face a 4× higher risk of rectal cancer (and 2× higher for colon cancer) than those born in 1950.
Early-onset GI cancers rose 14.8% between 2010 and 2019; pancreatic rates climbed 4.34% per year in 25–29-year-olds.
Obesity (BMI ≥30), Western diets, and fatty liver disease drive most of these cancers, which are sporadic, not inherited.
Younger patients often face delayed diagnoses, more aggressive treatment with marginal benefit, and greater “financial toxicity.”
BOSTON — Americans born in 1990 have four times the risk of developing rectal cancer compared to those born in 1950, according to a sweeping analysis that reveals how dramatically cancer patterns have shifted across generations. This alarming trend extends beyond a single cancer type; gastrointestinal cancers among people under 50 have surged by nearly 15% in just one decade, transforming diseases once considered rare in young people into leading killers.
Published in the British Journal of Surgery and led by researchers from the Dana Farber Cancer Institute and Harvard Medical School, the review examined cancer trends across multiple databases and studies. Between 2010 and 2019, cases of early-onset gastrointestinal cancers jumped by 14.8%, with colorectal cancer now ranking as the top cancer killer for men under 50 and second for women in that age group.
Most of these cancers aren’t caused by inherited genetic defects. Instead, researchers point to environmental factors tied to modern life: soaring obesity rates, diets dominated by processed foods, sedentary lifestyles, and exposures that previous generations simply didn’t face. “The rising incidence demonstrates a birth cohort effect, implicating environmental factors, such as diet and lifestyle,” the researchers wrote.
The increases hit certain groups hardest. Hispanic patients represent more than 22% of young adults diagnosed with stomach cancer, compared to just 7% of older patients. Black, Hispanic, and indigenous populations face disproportionately higher rates of early-onset colorectal cancer compared to their White counterparts.
Why are so many adults under 50 being diagnosed with colorectal cancer? (© SciePro – stock.adobe.com)
Why Cancer Rates Are Rising in Young Adults
Colorectal cancer incidence among Americans under 50 jumped from 5.9 cases per 100,000 people in 2000 to 8.4 cases per 100,000 by 2017. Among adults aged 25–29, pancreatic cancer incidence climbed by 4.34% per year beginning in the mid-1990s. Stomach cancer rates rose by 1.6% per year among women under 50 between 2010 and 2019, while esophageal cancer cases increased by 6.86% per year in 30–39-year-olds and showed a steady early-onset rise overall.
These patterns mirror troubling trends worldwide, particularly in wealthy nations where Western lifestyles have taken hold. European countries reported significant increases in early-onset colorectal cancer from 2004 to 2016, with the steepest rises — 7.9%, 4.9%, and 1.6% per year — among people in their twenties, thirties, and forties, respectively.
Several key factors appear to drive this health emergency. Obesity emerges as perhaps the strongest risk factor. Studies consistently show that people with a body mass index of 30 or higher face nearly double the risk of developing early-onset colorectal cancer. Diet plays an equally critical role: a Western eating pattern high in red meat, processed foods, sugar-sweetened drinks, and refined grains, while low in fruits and vegetables, has been linked to higher cancer risk. Heavy alcohol use and smoking further compound these effects.
Non-alcoholic fatty liver disease represents another major factor largely absent in past generations. This condition, which affects roughly 25% of adults globally and has exploded alongside rising obesity, significantly increases gastrointestinal cancer risk even in people who aren’t severely overweight.
Unique Challenges Young Cancer Patients Face
Beyond rising numbers, young adults with gastrointestinal cancers encounter challenges that older patients typically avoid. Diagnosis often comes later because neither patients nor doctors initially suspect cancer in someone so young. This delay frequently means the disease has progressed to more advanced stages by the time it’s detected.
Younger patients tend to receive more aggressive treatment than their older counterparts, even though research suggests this intensive approach doesn’t necessarily improve survival outcomes. Studies show that those under 50 are significantly more likely to receive chemotherapy and radiation, but show only marginal survival improvements compared to older patients receiving less intensive treatment.
Financial devastation often follows diagnosis. Researchers have documented that younger cancer patients experience what they term “financial toxicity” at much higher rates than older patients. This stems partly from being in peak earning years while facing massive medical bills, and partly from having young families to support during treatment.
Quality of life impacts can be particularly severe for younger patients. Treatments like pelvic radiation for rectal cancer can affect fertility, sexual function, and bowel control. These concerns are especially relevant for people who may have decades of life ahead of them.
Cancer disparities along racial and ethnic lines are stark and getting worse. Analysis of California cancer registry data showed that Black Americans had an early-onset colorectal cancer rate of 12.2 per 100,000 compared to 9.2 per 100,000 for White Americans. Five-year survival rates range from 57.6% for Black patients to 69.1% for non-Hispanic White patients.
Black adults are significantly more likely to be diagnosed with cancer, and have lower five-year survival rates. (© Seventyfour – stock.adobe.com)
How Healthcare Is Responding to Rising Cancer Rates
Healthcare systems are racing to adapt to this new reality. In 2021, the United States lowered the recommended age for colorectal cancer screening from 50 to 45, but many experts worry this reactive approach isn’t sufficient.
Current treatment guidelines don’t differentiate between young and older patients, despite growing evidence that early-onset cancers may behave differently at the molecular level. Young patients often have more aggressive disease features and different genetic profiles, yet they receive essentially the same treatment protocols developed primarily based on studies of older patients.
Some promising developments offer hope. Recent clinical trials have shown that certain intensive treatments may be safely scaled back without compromising outcomes. This is particularly important for younger patients facing decades of potential treatment-related side effects.
Research efforts are now focusing intensively on understanding why certain birth cohorts face higher risks and identifying critical windows during childhood or adolescence when environmental exposures have the most lasting impact. Scientists are also working to develop prevention strategies and screening methods tailored specifically for younger populations.
However, these medical advances won’t address the root causes driving this epidemic. As long as obesity rates continue climbing, diets remain dominated by processed foods, and sedentary lifestyles persist, the cancer rates documented in this review are likely to worsen rather than improve. Without dramatic changes to the environmental factors driving these increases, an entire generation faces rectal and other gastrointestinal cancer risks that previous generations never had to confront.
Disclaimer: This article summarizes a narrative review of existing studies and registry data; it does not constitute medical advice. Readers should consult healthcare professionals for personalized guidance on cancer risk and screening.
Paper Summary
Methodology
This study represents a narrative review rather than original research with participants. The authors systematically analyzed existing research literature, cancer databases, and registry data to examine trends in early-onset gastrointestinal cancers, defined as those diagnosed before age 50. They reviewed epidemiological data from multiple sources including the SEER (Surveillance, Epidemiology, and End Results) database, various national cancer registries, and published studies from around the world. The review focused on colorectal, esophageal, stomach, and pancreatic cancers, examining patterns in incidence, risk factors, clinical characteristics, genetic features, and treatment outcomes. Rather than conducting new experiments, the researchers synthesized findings from hundreds of existing studies to provide a complete overview of this emerging health issue.
Results
The review documented consistent increases in early-onset gastrointestinal cancer rates globally, with the United States seeing a 14.8% increase between 2010 and 2019. The most striking finding was a birth cohort effect, where Americans born in 1990 face twice the risk of colon cancer and four times the risk of rectal cancer compared to those born in 1950. While 10–25% of early-onset cases involve inherited genetic mutations, the majority are sporadic and linked to environmental factors including obesity, Western dietary patterns, non-alcoholic fatty liver disease, smoking, and alcohol consumption. The increases disproportionately affect Black, Hispanic, and indigenous populations, with significant racial disparities in both incidence and survival rates. Younger patients typically present with more advanced disease stages and receive more intensive treatment than older patients, though survival outcomes vary across different studies and cancer types.
Limitations
As a narrative review synthesizing existing literature rather than conducting original research, this paper’s limitations stem from the quality and scope of the studies it analyzed. The authors noted that different studies use varying definitions of “early-onset” cancer, ranging from under 40 to under 60 years old, making direct comparisons challenging. Some cancer registries don’t consistently distinguish between different tumor subtypes, which can affect trend analyses. The review also acknowledged that deeper genomic characterization through whole exome or genome sequencing of large patient cohorts is needed to better understand the molecular differences between early-onset and average-onset cancers. Additionally, many of the risk factor associations come from observational studies rather than controlled trials, limiting the ability to establish definitive causal relationships.
Funding and Disclosures
The authors declared no funding sources for conducting this review. Dr. Kimmie Ng reported receiving institutional research funding from Pharmavite and Janssen, participating in consulting and advisory board roles for multiple pharmaceutical companies including CytomX, Revolution Medicines, AstraZeneca, Agenus, Johnson & Johnson, Etiome, GlaxoSmithKline, and CRICO, and serving as an Associate Editor for JAMA journal. The other authors, Sara K. Char and Catherine A. O’Connor, declared no conflicts of interest or competing financial relationships related to this work.
Publication Information
This review was published in the British Journal of Surgery in 2025, authored by Sara K. Char and Catherine A. O’Connor from Harvard Medical School and Dana-Farber Cancer Institute in Boston, Massachusetts, along with Kimmie Ng from the Department of Medical Oncology at Dana-Farber Cancer Institute. The manuscript was received on April 1, 2025, and accepted for publication on April 14, 2025. DOI: https://doi.org/10.1093/bjs/znaf102.