This is a prospective study investigating the disease course of patients with colorectal cancer that have had their cancer spread to their liver. The aim of this study is find potential biomarkers for disease recurrence and therapeutic targets for prognostic information.

Colorectal cancer (CRC), the 2nd leading cause of cancer mortality, often has a pattern of targeting the liver during initial metastases. The Comprehensive Genomic Profiling of Colorectal Cancer Patients with Isolated Liver Metastases to Understand Response and Resistance to Cancer Therapy (COMPARISON) study aims to assess the disease course of CRC by collecting primary tumor and metastatic liver specimens following pre-operative chemotherapy. If relapse occurs following surgical resection of the liver, biopsies will also be done for molecular analysis. As a result, these samples can be analyzed for chemotherapy resistance mechanisms and therapeutic targets to determine potential clinical outcomes for this particular subset of CRC patients.

Eligibility Criteria:

1. Patients must have histologically confirmed CRC with isolated liver metastasis
2. Patients must be planned for a hepatic metastasectomy
3. Patients must have received at least 3 cycles of chemotherapy (FOLFOX or FOLFIRI with or without Bevacizumab) prior to the planned hepatic metastasectomy
4. Primary tumor must be considered resectable with a plan for this to either occur concurrently with the liver resection or subsequent to this.
5. If primary has already been resected before liver resection, archival tissue must be available for genomic analysis
6. Patients must be 18yrs of age or older
7. Ability to understand and willing to sign a written informed consent document

Exclusion Criteria:

1. Patients with un-resectable or borderline resectable isolated liver metastases as judged by the multidisciplinary hepatobiliary tumor board at PM or BCCA after a course of pre-operative chemotherapy will be excluded
2. Patients with evidence of possible metastatic disease at any sites outside the liver are not eligible
3. Patients with any major co-morbidity or co-morbidities that will render liver resection very high risk in investigator's opinion
4. Any other condition that would, in the Investigator's judgment, contraindicate the patient's participation in the clinical study due to safety concerns or compliance with clinical study procedures.
5. Patients with a previous history of another primary cancer treated within 5 years of study entry are not eligible except those with basal cell or squamous cell carcinoma of the skin and intraepithelial neoplasia.

metastatic colorectal cancer, isolated liver metastases, at least 3 rounds of chemotherapy (FOLFOX or FOLFIRI +/- Bevacizumab) prior to planned liver resection