Intratumoral heterogeneity of colorectal cancers with distant metastases

Copy number analyses of regionally separated biopsies from primary and metastatic lesions of five colorectal cancers A total of 35 intratumoral biopsies were obtained from primary and metastatic lesions of five colorectal cancers. Board-certified pathologists reviewed the hematoxylin&eosin stained sections and identified tumor-rich regions (> 80% purity) to ensure minimal contamination of normal tissues. We selected two to six different areas for biopsy that were at least 5mm apart in primary and distant metastatic lesions from a same patient. Copy number profiling was performed using Agilent 180K platform according to the manufacturer's protocol. The genomic DNA obtained from the adjacent normal tissues were used as reference genomic DNA for the tumor DNA of the corresponding patients.