# Adiposity and Early-Onset Colorectal Cancer

Excess adiposity is a credible contributor to early-onset colorectal cancer, but its precise causal effect before50 and its share of the incidence rise remain less securely identified than the broader colorectal-cancer link.

The preregistered primary-subclaim rule returns SC2 Γ for the precise age-defined causal claim. This is a bounded assessment of direct early-onset causal identification, not a refutation of the prospective association or the broader adiposity–colorectal-cancer causal literature. The cohort dose-response and genetic-natural-experiment equivalents were evaluated; their age/timing and system scopes do not silently become the exact registered outcome.

Associational and mechanistic boundaries are observed; these do not manufacture a successful direct under50 perturbation. Early-life exposure and early cancer diagnosis are distinct. No responder-defined scope restriction is introduced, and the direct causal-effect magnitude or majority-trend claim remains open.