Objectives <p>Gastrointestinal neuroendocrine neoplasms (GI-NENs) exhibit heterogeneity in biological behavior, making it difficult to predict prognosis. We established the P Grade based on ⁶⁸Ga-DOTANOC and ¹⁸F-FDG PET dual scans and evaluated the prognostic significance in patients with metastatic GI-NENs.</p> Methods <p>The P Grade was categorized based on SSTRI/FDG uptake into P1 (DOTANOC positive/FDG negative), P2 (DOTANOC positive/FDG positive), and P3 (DOTANOC negative/FDG positive). Patients would be classified into P grades based on dual scan. results. Then they were divided into medical treatment and surgical group. The correlation of P Grade with progression-free survival (PFS) and overall survival (OS) was evaluated using Kaplan-Meier analysis, and performed univariate and multivariate analyzes of relevant clinicopathological variables with PFS and OS.</p> Results <p>Two hundred forty-three patients with metastatic GI-NENs were enrolled. P Grade exhibited notable statistical significance with OS and PFS in overall cohort on univariate and multivariate analysis (all <i>p</i> &lt; 0.01). In surgery group, P Grade demonstrated independent predictive value for OS and PFS (all <i>p</i> &lt; 0.01). In medical treatment group, P Grade demonstrated predictive value for PFS (all <i>p</i> &lt; 0.01) and predicted OS (univariate P3vsP1, <i>p</i> &lt; 0.01). Additional predictors of OS and PFS included WHO grade, age at diagnosis, location of primary site, sex and extrahepatic disease, they all had statistical significance with OS or PFS (<i>p</i> &lt; 0.05) except sex factors.</p> Conclusion <p>Our cohort study demonstrates that P Grade obtained by combining ⁶⁸Ga-DOTANOC and 18&#xa0;F-FDG PET is a significant prognostic indicator for patients with metastatic GI-NENs, regardless of whether received medical treatment or surgical resection of the primary site. This will bring a new predictive tool to clinical practice and be applicable to patients with different treatment modalities.</p>