Development and Internal Validation of a SEER-Based Prediction Model for Survival in Poorly and Undifferentiated Colorectal Neuroendocrine Neoplasms

Poorly and undifferentiated colorectal neuroendocrine neoplasms (CR-NENs) are rare and highly aggressive tumors with limited individualized prognostic assessment. Conventional staging systems are insufficient to capture heterogeneity, and dedicated prognostic models for this subgroup remain lacking. This study aimed to develop and internally validate a multivariable prediction model for survival in patients with CR-NENs.