Why People Are Getting Cancers at Younger Ages
The increase in early-onset cancers appears to be due to a combination of genetic predisposition, environmental exposures, and lifestyle changes that have occurred over multiple generations since the mid-20th century. 1
Documented Trends in Early-Onset Cancer
Since the mid-1990s, cancer incidence rates in young adults have been increasing. Data shows:
- Incidence rates among people under 40 years have slowly increased by approximately 0.2% per year 2
- By 2030, an estimated 15% of colorectal cancers will be diagnosed in younger adults 2
- Colorectal cancer incidence rates in adults under 50 have been increasing by approximately 2% per year since 2003 2
- Colorectal cancer is now the leading cause of cancer death in men and second in women under 50 years in the United States 2
Key Contributing Factors
Genetic and Hereditary Factors
- Hereditary cancer predisposition is more common among young cancer patients 2
- Family cancer syndromes account for less than 5% of cancer cases in young adults, suggesting most cases are not primarily hereditary 3
- Genetic susceptibilities may interact with environmental exposures 1
Environmental and Lifestyle Changes
Multiple generational changes in exposures appear to be driving the increase:
- Diet and nutrition changes
- Lifestyle modifications
- Rising obesity rates
- Environmental pollutants
- Microbiome alterations 1
Biological Differences in Early-Onset Cancers
Young patients often present with more aggressive disease characteristics:
- Higher proportion of grade 3 tumors
- More triple-negative and HER2-positive breast cancers
- Greater lymphovascular invasion
- Higher rates of lymphocytic infiltration
- More basal-like and HER2-enriched tumors on gene expression profiling 2
Cancer Types Affected
Early-onset cancer increases have been documented in multiple organs:
- Breast
- Colorectum
- Endometrium
- Esophagus
- Extrahepatic bile duct
- Gallbladder
- Head and neck
- Kidney
- Liver
- Bone marrow
- Pancreas
- Prostate
- Stomach
- Thyroid 1
Survival and Prognosis Concerns
Young cancer patients face unique challenges:
- Less favorable outcomes compared to older patients with similar cancers 2
- Particularly poor outcomes for young patients with luminal-A like breast tumors 2
- Lack of progress in survival improvement among adolescents and young adults compared to other age groups 3
- Males have worse prognosis than females in the 15-29 age group 3
- Racial disparities exist, with non-Hispanic whites having better survival than African Americans 3
Clinical Implications
Screening Recommendations
The increasing incidence of early-onset cancers has prompted changes in screening guidelines:
- The NCCN has updated colorectal cancer screening guidelines to address the rising rates in younger adults 2
- Screening strategies need to be updated for appropriate and timely diagnosis in younger populations 2
Assessment of Risk
When evaluating young patients:
- Accurate assessment of family history is essential, documenting details of cancer diagnoses in relatives out to third degree 2
- Features suggesting genetic predisposition include unusually young age at cancer onset, multiple cancers in one individual, or multiple blood relatives with cancer at the same or related sites 2
- Young age alone is not a high-risk factor for aggressive behavior in some cancers (like basal cell carcinoma), but patients who develop cancer at a young age may benefit from regular follow-up 2
Future Directions
To better understand and address early-onset cancers:
- Prospective cohort studies with dedicated biobanking and data collection technologies are needed 1
- Increased awareness among both the public and healthcare professionals is critical 1
- Research into early-life exposures and their implications for multiple cancer types is essential 1
The rising trend of early-onset cancers represents an emerging public health concern that requires both immediate clinical attention and long-term research to identify and mitigate causative factors.