The purpose of this study is to learn more about malignant colorectal polyps and the risk of the cancer remaining, coming back, or spreading after the polyp is removed. The researchers also want to understand how patients and doctors make decisions about treatment after a malignant polyp is removed.

Additionally, the researcher will collect information medical records, including results from tests, imaging scans, lab work, and pathology reports. The researchers may also collect images from your colonoscopy and copies of pathology slides the polyp. The researchers will also follow the patient's health over time through regular doctor visits. If the patient does not have a scheduled visit, a member of the study team will contact the patient by phone at 1 year, 3 years, and 5 years after the patient joins the study to ask about their health.

Criteria:

• Documentation of Disease
• Patients must have one malignant polyp, pathologically confirmed within 90 days of enrollment. Patients with multiple malignant polyps are not eligible.
• Definition of Disease Colorectal carcinoma (CRC) develops within serrated or adenomatous polyps. Early CRC represents invasion into the submucosa and frequently presents within the precursor polyp which is termed a 'malignant polyp'(23).

The term malignant polyp specifically refers to a colorectal lesion with cancer invading the submucosa but not extending into the muscularis propria. These lesions are classified as pT1 in the TNM classification system (24)

Prior Treatment Endoscopic resection of the polypoid lesion-malignant polyp with simple snare polypectomy, conventional endoscopic mucosal resection (EMR), or endoscopic submucosal dissection (ESD) (25).

• Age ≥ 18

The following Colorectal Surgery outpatient clinic will be prospectively screened. Other patients identified in other clinics at Memorial Sloan-Kettering Cancer Center who fulfill the eligibility criteria may also be invited to participate.

Memorial Sloan Kettering Cancer Center supports the international committee of medical journal editors (ICMJE) and the ethical obligation of responsible sharing of data from clinical trials. The protocol summary, a statistical summary, and informed consent form will be made available on clinicaltrials.gov when required as a condition of Federal awards, other agreements supporting the research and/or as otherwise required. Requests for deidentified individual participant data can be made following one year after publication and for up to 36 months later. Deidentified individual participant data reported in the manuscript will be shared under the terms of a Data Use Agreement and may only be used for approved proposals. Requests may be made to: crdatashare@mskcc.org.