Intra-individual genetic heterogeneity among liver metastases in metastatic colorectal cancer.

555 Background: Almost 50% of patients with colorectal cancer (CRC) develop liver metastases, often as multiple simultaneous metastatic deposits. Up to 25% of the patients are eligible for partial liver resection, but 70% will relapse after surgery and there are currently no good criteria to select patients who will benefit from the treatment. Genetic heterogeneity among metastatic deposits has great potential impact on disease progression, but has not been well described. Methods: Totally 134 liver metastatic deposits were collected from 45 patients undergoing partial liver resection for metastatic CRC according to a prospective study protocol. All deposits were analyzed for high-resolution DNA copy number variation using the Affymetrix SNP Array 6.0. A novel bioinformatic approach was used to measure intra-individual genetic heterogeneity among the metastatic deposits. Results: The patients showed a large variation in the level of intra-individual metastatic heterogeneity, and heterogeneity was independ...