Testing adds the most value at two points: at the time of a cancer diagnosis, where it can inform treatment decisions and can be eligible for certain immunotherapy drugs that work particularly well against Lynch-related tumors, and before any cancer develops, in people with a known family history, where it allows preventive planning to begin early. A confirmed positive result typically leads to:

*Colonoscopies starting around age 20–25, repeated annually or every 1–2 years.
*Additional screening for endometrial, gastric, or urinary tract cancers depending on the gene involved.
*Discussion of risk-reducing surgery (such as hysterectomy and removal of ovaries) once childbearing is complete, for those with a uterus.
*Cascade testing- offering a targeted segregation of the change found in proband to first-degree relatives, since each one independently has a 50% chance of carrying the same variant.