Summary of Key Findings
The incidence of cancers traditionally associated with older adults (such as colorectal, cervical, and liver cancers) is on the rise among young people under 50 years old globally, with over 9,000 new cases diagnosed each day. Experts have discussed various potential causes at academic conferences, including obesity, ultra-processed foods, environmental chemicals (such as pesticides), and changes in disease classification criteria, but no definitive answers have yet been established. What’s more concerning is that the cancer risk associated with this generation may persist into old age, potentially leading to a higher overall cancer burden in the future.
1. The Current Situation of Increasing Cancer Incidence Among Young People: Which Cancers Are Affecting Them?
Not all types of cancer are increasing among young people; it depends on the specific type:
- Colorectal Cancer: The number of advanced cases among individuals aged 20–49 in the United States is rising by 3% annually, and in 2023, it became the leading cause of cancer death in this age group.
- Cervical and Liver Cancers: Incidence and mortality rates are increasing among younger women.
- Pancreatic Cancer: The incidence is rising across all age groups (in part due to changes in definition), with young people also being affected.
Global data show that 9,000 people under 50 are diagnosed with cancer each day, but experts warn that not all cases can be attributed to the same factors; some may be due to changes in detection or classification methods, while others represent a true increase in risk.
2. Some Increases May Be Illusory: Changes in Disease Definitions Can Affect Statistics
For example, in the early 2010s, medical experts included “pancreatic neuroendocrine tumors” (tumors that develop in the insulin-producing areas of the pancreas) within the definition of pancreatic cancer. Before this change, the incidence of pancreatic cancer was increasing slowly; however, with the broader definition, the incidence increased in all age groups, including young people. Experts suggest that these classification changes can explain part of the rise in early-onset pancreatic cancer cases, but not the entire phenomenon.
3. Dietary and Environmental Factors: Possible Contributing Factors
- Obesity: Known to be associated with colorectal and cervical cancers, many young patients are not overweight, so obesity is not the only factor.
- Ultra-Processed Foods: Studies have found that young women who consume large amounts of processed foods (such as chips, fast food, and packaged snacks) have a higher risk of developing colorectal polyps, an early sign of cancer, even when controlling for obesity factors.
- Chemicals: Some studies have linked early-onset colorectal cancer to exposure to the herbicide “dicofol,” commonly used in ranches and roadside weed control, but a direct causal relationship has not been confirmed and requires further research.
4. Bacterial Toxins in the Intestine: Even Children May Be Affected
Certain types of E. coli in the intestine produce toxins that can cause DNA mutations, which have been linked to colorectal cancer. Last year, researchers found that these mutations are more common in early-stage colorectal tumors in young people than in older adults. This year, even more alarming findings showed that the level of these mutations in the colons of children under 5 years old is comparable to that of middle-aged adults! Experts suggest measures to prevent children from being exposed to these toxins at an early age, but many questions remain, such as why the mutation rate does not increase with age among young people. It may be due to a combination of factors.
5. Future Implications: Higher Cancer Risk for This Generation in Old Age
Experts mention the “birth cohort effect”—young people born in recent decades (such as the Gen Z and Millennial generations) have a higher risk of cancer at the same age as their parents. This increased risk will carry over into old age, potentially leading to significantly higher overall cancer incidence when they reach their 60s and 70s. Therefore, the current increase in cancer cases among young people is actually a precursor to a potential cancer outbreak among middle-aged and older adults in the next 20–30 years.
In conclusion, there is no single culprit for this trend; it is likely the result of a combination of factors (diet, environment, microorganisms, etc.) acting over time. To determine the exact causes, more research focused on young people is needed. For the general public, reducing the consumption of ultra-processed foods, maintaining a healthy weight, and avoiding exposure to harmful chemicals may be the first steps in lowering cancer risk.