A large-scale community-based study from Taiwan provides compelling evidence that initiating colorectal cancer screening at age 40 significantly reduces both cancer incidence and mortality compared to starting at the traditional age of 50. The research, published in JAMA Oncology, analyzed data from 263,125 Taiwanese adults and found a 39% reduction in colorectal cancer mortality and 21% reduction in incidence among those who began fecal immunochemical test (FIT) screening between ages 40-49.
Substantial Risk Reduction Demonstrated
The study tracked participants through 2019, comparing outcomes between early screeners and those who began screening at age 50. Among participants who received early and continued screening (39,315 individuals), the colorectal cancer incidence rate was 26.1 cases per 100,000 person-years (95% CI, 22.3-29.9), compared with 42.6 cases per 100,000 person-years (95% CI, 40.5-44.7) in the group that began screening at age 50 (223,810 individuals).
Mortality rates showed even more dramatic differences. The early screening group experienced 3.2 deaths per 100,000 person-years (95% CI, 1.9-4.6) versus 7.4 deaths per 100,000 person-years (95% CI, 6.5-8.2) in the standard screening group.
Propensity score-matched analyses confirmed these benefits, showing a 21% reduction in colorectal cancer incidence (adjusted relative risk [aRR], 0.79; 95% CI, 0.67-0.94) and a 39% reduction in mortality (aRR, 0.61; 95% CI, 0.38-0.98) for early screeners. The extended nonadherence adjustment model yielded similar results with a 25% reduction in incidence (aRR, 0.75; 95% CI, 0.72-0.77) and 34% reduction in mortality (aRR, 0.66; 95% CI, 0.62-0.71).
Rising Cancer Rates Drive Screening Policy Changes
The research addresses a growing public health concern as colorectal cancer increasingly affects younger populations. Since the early 2010s, colorectal cancer incidence in individuals under age 50 has been increasing by approximately 3% each year. Recent data shows a 500% increase in cases among children aged 10 to 14 years over the past two decades, though overall numbers remain low.
"These findings highlight FIT's effectiveness in this younger age group and support recommendations to lower the screening initiation age," wrote the researchers. "Importantly, the long-term benefits of early screening were consistently observed across multiple study designs and statistical adjustments for self-selection bias."
Implementation Strategies Show Promise
A separate randomized clinical trial published in JAMA examined effective approaches for engaging younger adults in colorectal cancer screening. The study of 20,509 average-risk adults aged 45-49 found that mailing FIT kits directly to patients achieved significantly higher screening rates than offering choices between different screening methods.
The default mailed FIT approach resulted in 26.2% screening participation (1,342 of 5,126 participants), substantially higher than active choice strategies: 16.4% for FIT-only choice, 14.5% for colonoscopy-only choice, and 17.4% for dual-modality choice. The absolute differences in screening rates compared to usual care ranged from -8.9% to -11.7% for all active choice groups (all P < .001).
Study Limitations and Future Directions
The Taiwan researchers acknowledged several limitations, including the lack of age- and sex-specific FIT cutoff values when early-age screening was implemented, which may have influenced screening accuracy. Cultural, genetic, dietary, and health system differences may also affect the applicability of findings to other populations.
Despite these limitations, the researchers believe their findings align with growing evidence supporting earlier screening. "This study found that initiating FIT screening at age 40 to 49 years was associated with further reduction in CRC mortality and incidence compared with starting screening at age 50 years," they wrote. "These results provide strong empirical support for lowering the CRC screening age, with substantial public health implications."
The implementation study researchers noted that their findings "highlight that health systems can effectively engage adults aged 45 to 49 years with mailed FIT outreach, a practice already adopted by health systems for adults aged 50 years and older."
