Researchers have released a large, comprehensive study examining U.S. cancer incidence (new diagnoses) and mortality (deaths) across different generations over time. Their goal was to compare cancer trends by birth year and measure whether younger generations are developing cancer more often than earlier generations.
The study’s headline finding is striking: Gen X and Millennials showed cancer incidence rates about 2 to 3 times higher than people born around 1955 for certain cancers. The researchers also reported that these younger generations appear more likely to develop 17 different cancer types, raising concern that the overall population risk is increasing—not just the detection rate.
Why This Study Matters
The same research team published earlier work in 2019 that flagged rising rates in eight cancer types among younger cohorts. But this new research goes further by assessing both incidence and mortality by birth year, helping close a major gap in long-term, generation-by-generation evidence.
The researchers also emphasized an important point: exposures early in life may shape cancer risk later, especially for cancers diagnosed at age 50 or younger. That means today’s higher risk in younger groups could carry forward as these generations age.
The Data Behind the Findings
The study analyzed a very large dataset, including:
- 23,654,000 people diagnosed with 34 cancer types
- 7,348,137 deaths from 25 cancers
- Diagnoses and deaths recorded between 2000 and 2019
Using this data, researchers identified 17 cancers with increasing incidence in Gen X and Millennials.
The 17 Cancer Types Reported as Increasing in Gen X and Millennials
The study reported increases in:
- Small intestine
- Cardia gastric
- Ovary
- Estrogen receptor–positive breast
- Non-HPV-associated oral and pharynx (in females)
- Liver and intrahepatic bile duct (in females)
- Kaposi sarcoma (in males)
- Anus (in males)
- Colorectal cancer
- Endometrial cancer
- Gallbladder and other biliary
- Pancreas
- Kidney and renal pelvis
- Myeloma
- Non-cardia gastric
- Leukemia
Where the Increases Look Most Pronounced
The rise in incidence was described as especially noticeable in cancers of the:
- Pancreas
- Kidneys and renal pelvis
- Thyroid
- Small intestine
Even more concerning: the researchers noted that mortality increased in five cancers, including:
- Liver
- Endometrial
- Gallbladder
- Testicular
- Colorectal
This matters because rising deaths suggest the pattern isn’t only due to better screening. In other words, it may reflect a real increase in risk at the population level, with new cases growing fast enough to offset treatment progress.
What Might Be Driving the Increase
The study focused on measuring the trend rather than proving direct causes. Still, researchers highlighted several likely contributors, including:
- Obesity (linked to 10 of the 17 cancers noted)
- Environmental toxins and pollutants
- Dietary shifts
- Sedentary lifestyle
- Altered sleep patterns
Obesity stood out as a major suspect because rates have climbed across age groups since the 1970s—and the sharpest rises have been seen in children and teens.
Gut Microbiome and the Western Diet
Researchers also pointed to the modern Western diet—often highly processed, high in sugar, saturated fats, and refined grains—as another potential contributor.
Importantly, they noted that processed foods may influence cancer risk in two ways:
- Indirectly, by promoting weight gain
- Directly, with links reported to higher risk of colorectal and breast cancers
For cancers affecting the digestive system that are not strongly tied to obesity, the researchers suggested another pathway: changes in the gut microbiome. They argued the microbiome may be shaped by:
- Long-term dietary patterns
- Antibiotic exposure
It’s Not All Bad News
While the study emphasized rising incidence in 17 cancers, it also reported declines in several areas—showing prevention efforts can work.
Key positives included:
- Lower cervical cancer risk in women born around 1990, linked to HPV vaccination availability during adolescence
- Declines in esophagus, larynx, and lung cancers, associated with reduced smoking rates
- In general, early detection has helped reduce mortality in some cancers, even as incidence rises
The Bottom Line
This research suggests a meaningful generational shift: Gen X and Millennials are experiencing higher incidence of multiple cancers, and for some cancers, mortality is rising too. The findings raise urgent questions about modern exposures—especially those affecting people early in life—such as diet patterns, obesity, and environmental factors.
At the same time, the declines in certain cancers show that public health actions and lifestyle changes can reduce risk. The study reinforces a crucial message: what happens in youth can shape health decades later, and understanding these trends is key to preventing future cancer burden.
Sources
- “Cancer Prevention with Nutrition and Lifestyle.” NCBI. Eva Kerschbauma and Volkmar Nüssler. July 23, 2019.
- “Differences in cancer rates among adults born between 1920 and 1990 in the USA: an analysis of population-based cancer registry data.” The Lancet. Hyuna Sung, PhD, et al. August 2024.
- “The importance of addressing early life environmental exposures in cancer epidemiology.” NCBI. Nicole M. Niehoff, Mandy Goldberg, and Alexandra J. White. April 5, 2022.
- “Western Lifestyle, Global Problem: Rising Rates of Cancer in the Young.” RGA. Hilary Henly. December 2020.
