Clinicopathologic Features and Staging Risk Factors of Early-Onset Colorectal Cancer

Inclusion criteria

• Age ≤ 50 years
• Pathologically confirmed colorectal neoplasia diagnosed at Shenzhen Hospital, Southern Medical University between 2016-01-01 and 2025-09-30, defined as colorectal cancer (any T stage) or high-grade intraepithelial neoplasia (HGIN).
• Available source documentation: complete or retrievable clinical record, endoscopy report, and pathology report sufficient to determine diagnosis and stage.
• De-identifiable data available for extraction (records can be coded and exported without direct identifiers).
• No requirement for additional patient contact (retrospective use of existing records with IRB-approved consent waiver or documented consent per ethics approval).

Exclusion criteria

• Secondary/metastatic colorectal tumor (colorectal involvement proven to be metastasis from another primary site).
• Prior history of other active malignancy within the last 5 years that could confound staging or outcomes, unless disease is in long-term remission and clearly documented.
• Insufficient documentation to determine pathological diagnosis or T stage (key pathology report missing or illegible).
• Critical data missing for primary outcome (e.g., pathology date or staging information) that cannot be resolved after source review.
• Duplicate records or irreconcilable data (same patient with conflicting identifiers/records that cannot be reconciled).
• Patients who received initial diagnostic or therapeutic care outside the study site with no accessible pathology or endoscopy reports at Shenzhen Hospital.