The CORRECT - MRD II study will prospectively enroll patients who have undergone complete surgical resection for stage II or III colorectal cancer. Maximum duration of participant participation is up to seven years from enrollment to study completion with up to five years of active follow up and up to two years of clinical (passive) follow up.

Inclusion Criteria:

1. Diagnosis of carcinoma of the colon or rectum (patients with lymphomatous, sarcomatous, or neuroendocrine features are not eligible).

2. Post complete surgical resection of CRC, with last surgery occurring within 180 days prior to enrollment are eligible if all of the following conditions are met:

   1. in the opinion of the surgeon, all grossly visible tumor was completely resected ("curative resection") and
   2. histologic evaluation by the pathologist confirms the margins of the resected specimens are not involved by malignant cells.

   i. Patients with T4 tumors that have involved an adjacent structure (e.g., bladder, small intestine, ovary, etc.) by direct extension from the primary tumor must have had all or a portion of the adjacent structure removed en bloc with the primary tumor and local radiation therapy will not be utilized.

3. Pathologic stage II or III

4. ECOG performance status ≤ 2 (0, 1 or 2).

5. Able to understand and provide informed consent.

6. Willing and able to comply with the study requirements, which includes the collection of approximately 43mL of blood for each research blood draw.

Exclusion Criteria:

1. Initiated adjuvant therapy for current CRC diagnosis (note: prior neoadjuvant therapy acceptable).

2. Pregnant or breastfeeding at time of enrollment.

3. Prior history of any invasive cancer (including CRC) within the past 3 years prior to informed consent, with the exception of non-melanoma skin cancer. Patients with a prior history of noninvasive (in situ) carcinomas may participate after definitive treatment.

4. Prior transplant history:

   1. Prior allogeneic hematopoietic stem cell transplant at any time.
   2. Prior solid organ transplant within the last 2 years prior to enrollment.

5. Multiple cancer diagnoses: Synchronous or asynchronous diagnoses (or suspicion) of multiple primary cancers at the time of eligibility screening.

Patients over the age of 18 who have undergone surgery for stage II or III colorectal cancer

Individual participant data that underlie the results reported in publications of the study will be shared after deidentification. This may include test, tables, figured, and appendices. The study protocol, statistical analysis plan (when applicable), informed consent form (when applicable). May not be reproduced nor disseminated outside of Exact Sciences without permission and the clinical study report (when applicable) will also be shared

Data will be available from 2 years and ending 4 years after publication

Proposals for access to data should be directed to clinicaltrials@exactsciences.com. To gain access, data requestors will need to provide a methodologically sound proposal and sign a data access agreement. Researchers are required to obtain necessary Institutional Review Board (IRB)/Institutional Ethics Committee (IEC) approvals or waivers as applicable to conduct research.