The purpose of this clinical study is to evaluate the accuracy of the fecal immunochemical test (FIT) in comparison to colonoscopy in patients with Lynch Syndrome (LS) who are undergoing colonoscopy surveillance.

Lynch syndrome (LS), the most common inherited cause of colorectal cancer (CRC) affecting about 1.2 million Americans. Colonoscopy starting early in adulthood and repeated yearly or biennially is the only recommended surveillance strategy which translates into about 25-50 lifetime colonoscopies. This intensive colonoscopy surveillance is not ideal because CRC risk varies widely by LS gene and age, colonoscopies are invasive, costly, and not readily accessible to all patients, and adherence is suboptimal.

This clinical study will examine the performance of the fecal immunochemical test (FIT) in Lynch Syndrome (LS) patients undergoing colonoscopy surveillance. In addition to assessing the characteristics of the FIT test, such as specificity, sensitivity, and both negative and positive predictive values, the study will also explore LS patients' attitudes toward and acceptability of non-invasive testing methods. This comprehensive approach aims to provide insights into both the diagnostic effectiveness of FIT and the potential for improving patient adherence to screening protocols through less invasive options.

Inclusion Criteria:

• Have a diagnosis of LS with a confirmed pathogenic variant in MLH1, MSH2, MSH6, PMS2 or EPCAM genes.
• Aged 20 - 80 years (for those with pathogenic variants in MLH1, MSH2, and EPCAM)
• Aged 30 - 80 years (for those with pathogenic variants in PMS2 or MSH6).
• Have an upcoming standard of care (SOC) colonoscopy appointment in line with standard LS surveillance guidelines (NCCN).
• Patients with previous colon surgery who still have 20cm or more of colon remaining
• Patients who are diagnosed with advanced neoplasia (e.g., advanced adenomas or cancers) and have NOT had endoscopic or surgical resection
• Willing to sign informed consent, collect stools samples and complete surveys

Exclusion Criteria:

• Individuals who have not proceeded with genetic testing and therefore are not known to have LS, despite family history and/or criteria for testing.
• Individuals who have previously undergone a subtotal or total colectomy.
• Newly diagnosed Lynch Syndrome patients < 20 years old with a pathogenic variant in MLH1, MSH2 or EPCAM, MSH6 or PMS2.
• Newly diagnosed Lynch Syndrome patients < 30 years old with a pathogenic variant in MSH6 or PMS2.
• Individuals who are pregnant.
• Individuals with inflammatory bowel disease or active malignancy.
• Individuals not willing or able to sign informed consent.

People aged 20 - 80 years who have been diagnosed with Lynch syndrome