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.
A Retrospective Cohort Study to Evaluate a Multigene assay to assess the recurrence risk of colorectal cancer.