350P Postoperative histopathological, clinical and molecular risk score for patients with colorectal liver metastases

Hepatic resection is considered the optimal potentially curative treatment for colorectal liver metastases (LM). The Genetic And Morphological Evaluation (GAME) score, which includes KRAS status, tumor burden score, CEA, lymph node metastases and extrahepatic disease, has been proposed as a preoperative tool to select patients (pts) for liver resection. Nevertheless, histological characteristics of LM have been presented as potential prognostic biomarkers to be considered after resection. This study aimed to create a postoperative score including histological characteristics. Clinical and pathological data were collected from 146 metastatic colorectal cancer pts undergoing liver resection between 2004 and 2019 at Hospital de Sant Pau. Histopathological changes in liver parenchyma such as immune phenotype (IP) and histological growth pattern (HGP) were documented to identify potential prognostic factors. We calculated the GAME score of each patient and added the histological characteristics that had a prognostic value in the multivariable analysis. Of the 146 LM analyzed, twenty-three pts had a desmoplastic HGP (16%), thirty-one (22%) had a desertic IP and a fibrotic capsule was described in 22.5% of the cases. In the univariable analysis, the desmoplastic HGP and the fibrotic capsule was associated with a better overall survival (OS) (102 vs 49.3 months, HR 0.44 95% CI 0.23-0.86; p= 0.013 and 89.3 vs 46.9 months; HR 0.56 95% CI 0.33-0.98; p=0.037). The desertic IP was associated with a shorter OS (34.2 vs 58.3 months; HR 1.77 CI 1.1-2.8; p= 0.01) and remained significant in the multivariable analysis (HR 1.95, CI 95% 1.16-3.23; p= 0.012). We added 1 point to the original GAME score if a desertic immune phenotype was observed, and pts were classified in three risk groups with significant differences in survival. The high-risk group (score ≥4) had a recurrence free survival (RFS) and OS of 12.7 and 36.6 months vs 30.7 and 89.3 months in the low-risk group (score 0-1), respectively (p<0.001 and p=0.007). The desertic immune phenotype in liver metastasis of CRC has a bad prognostic value and could be considered to assess adjuvant treatment after hepatic resection.