Cohort Study to Evaluate the Relapse Risk Test in Colorectal Cancer

Colon cancer is the fourth most prevalent cancer for both men and women and also the third most common cause of cancer-related deaths worldwide. The primary consideration in deciding whether the moderate benefits from adjuvant chemotherapy for colon cancer (a 20% to 25%proportional reduction in the risk of recurrence and death) will be worth-while is the likelihood of disease recurrence, with larger absolute benefits for higher-risk patients. Nevertheless, the recurrence of cancer and decisions about its treatment still rely largely on classic histopathological and immuno histochemical techniques. The purpose of this study is to validate a previously developed multigene assay for a more quantitative approach to predict the recurrence risk and rational individualization of treatment are needed. A retrospective cohort of stage II and stage III patients with average 5 years follow up after resection surgery will be selected. Formalin fixed paraffin-embedded (FFPE) tumor tissue collected during patients' resection surgery with either recurrence or non-recurrence follow-up will be used validate the test. This multigene assay result will provide a precise estimate of the risk of recurrence and chemotherapy benefit for colorectal patients to help guide the most appropriate treatment decision. Three types of patients in this study: Cohort A People ages 20 year or older who were diagnosed with anatomic stage II, T3, MMR-P colorectal cancer and had recurrence of tumor within 5 years follow-up. FFPE tumor tissue samples must be collected after surgical resection and before starting chemotherapy or other treatment. Cohort B People ages 20 year or older who were diagnosed with anatomic stage II, T3, MMR-P colorectal cancer and had no-recurrence of tumor within 5 years follow-up. FFPE tumor tissue samples must be collected after surgical resection and before starting chemotherapy or other treatment. Cohort C People ages 20 year or older who were diagnosed with stage III A/B colorectal cancer and had recurrence of tumor within 5 years follow-up. FFPE tumor tissue samples must be collected after surgical resection and before starting chemotherapy or other treatment. Cohort D People ages 20 year or older who were diagnosed with stage III A/B colorectal cancer and had no-recurrence of tumor within 5 years follow-up. FFPE tumor tissue samples must be collected after surgical resection and before starting chemotherapy or other treatment.