Treatment of Lynch Syndrome in Colorectal Cancer

When a patient is diagnosed with colorectal cancer, identifying an underlying hereditary cause — specifically Lynch syndrome — has significant clinical consequences for both the patient and their family. Guidelines support a systematic evaluation pathway to detect these cases early.

This protocol addresses patients with colorectal cancer in whom Lynch syndrome is suspected or has not yet been excluded. Tumor-based testing for microsatellite instability (MSI) or immunohistochemistry (IHC) is recommended as the entry point for all such patients to identify those who may have Lynch syndrome.

The management pathway centers on germline genetic evaluation. The full structured protocol — including which patients qualify for each step and how findings guide subsequent decisions — is available in the complete regimen below.