The outcome of patients (pts) with metastatic colorectal cancer (mCRC) based on site of metastases (mets) and the impact of molecular markers and site of primary cancer on metastatic pattern.

3560Background: Although liver is the commonest site of mets in pts with CRC, pattern of spread is variable and may reflect different biology in different subsets of pts. Methods: This is a retrospective analysis to explore the outcome of pts with mCRC based on their site of mets at diagnosis and to identify tumor characteristics which could predict the site of mets. Pts from 2 Australian databases, BioGrid (BG) and South Australian Cancer Registry (SA), from 01/2006 to 12/2015 were grouped into 5 cohorts; lung only, liver only or any pts with brain, bone or peritoneal mets. Overall survival (OS) for each group was compared with the rest of the sample using Kaplan Meier analysis and the log rank test separately in each dataset. Mantel-Haenszel Chi-squared test was performed in pooled data to assess the association between KRAS, BRAF, Micro satellite instability (MSI), site of primary and site of mets. Results: 5967 pts were included. In both datasets median OS was significantly higher when mets were limit...