Determinants of permanent liver limited disease (pLLD) in metastatic colorectal cancer (mCRC)

3561 Background: CRC is a complex and heterogeneous disease, with the liver being the most frequent site of metastasis. Around 20% of patients will always progress exclusively in the liver. These patients may be candidates for more aggressive therapeutic procedures that will impact in their outcome. LIVERMET SURVEY Database (LMSD) is a prospective international database, focused on patients operated for CRC liver metastasis, whether resected or not, which purpose is to evaluate patient outcomes and prognostic factors for these resected patients. We propose to analyse all patients enrolled in the (LMSD) to better characterised those determinants that are associated with pLLD. Methods: We analyzed all patients included in the LMSD. Patients with relapse of their disease after the first liver surgery were selected. In order to test associations between hepatic only and extrahepatic metastasis, a univariate and multivariate logistic model was performed with the variables considered clinically more relevant. Imputation of missing data using the mice method (Multivariate Imputation via Chained Equations) was performed. All analyses were performed with R 4.1.1 software. Results: A total of 8715 patients out of 33581 (26%) included in the LMSD presented disease recurrence after a first liver surgery. During their oncological history, pLLD occurred in 1392 patients (16%), and extrahepatic relapse was presented in 7323 patients (84%). The characteristics of patients with pLLD were as follows: 58.4% patients presented synchronic disease, 20.2% had right sided primary tumor, 58.6% presented unilateral disease at time of first hepatic surgery and 20.4% of patients presented R1 surgery. In multivariant analysis, right sided and rectum (HR 0.82. p = 0.001), unilateral liver involvement (HR 0.74, p < 0.001) and > 3cm of diameter in greatest lesion with maximum of 3 lesions (HR 0.85, p = 0.02) were predictive determinants of extrahepatic disease. Only synchronic metastases (HR 1.29, p < 0.001) and male sex (HR 1.15, p = 0.028) were associated with pLLD. Molecular information according to RAS, BRAF and MSI status was not evaluable in a majority of patients since this item has been recently implemented in the questionnaire. Conclusions: This study confirms that about 16% of patients with LLD mCRC will be pLLD mCRC. Despite clinical determinants like synchronic metastatic disease, which is associated with pLLD, further analyses including molecular determinants are needed. Identifying those determinants of pLLD in a scenario where more extreme surgeries and liver transplantations are being considered is a great challenge that needs to be addressed.