# Narration and storyboard draft: Adiposity and Early-Onset Colorectal Cancer

Authored draft, approximately 60–90 seconds; no rendered video claimed.

Why is colorectal cancer rising in younger adults? Excess body fat is a credible contributor, but three questions must stay separate: whether it tracks with individual risk, whether it causes the age-specific disease, and whether it explains most of the population increase. Our HSEF v5.3 review examines58 original reports and selected Methods and Results. Prospective studies directly link obesity with cancer before50 in some settings. Genetic analyses and experiments strengthen the broader colorectal-cancer causal case, while many large studies use all ages or a before55 definition. Childhood weight is not interchangeable with adult weight, and a precursor polyp is not a cancer diagnosis. Diet, antibiotic exposure and microbial mechanisms also have different evidence. Colibactin has a specific experimental mutation signature that appears more often in younger tumors; current microbial presence does not prove the timing or cause of infection. Screening and classification influence some trends, and inherited pathways explain distinct subgroups. The remaining causal question needs matched age-specific natural experiments and explicit risk decomposition, not a blanket explanation for every cancer. Consensus was used to identify and cross-check specific aspects. Its pooled-cohort age threshold, case-control effect measure, inherited categories and categorical majority-growth statement were reconciled against original reports; provider paper counts are not the number of originals examined.

1. Show the exact claim, grade and confidence.
2. Show selected publication milestones; label experimental systems and clinical endpoints.
3. Contrast the strongest result with its source-specific limitation.
4. End with the boundary experiment and primary-source links.

Use authored schematics; do not depict Consensus meters as causal confidence or reproduce publisher graphics without appropriate permission.