All cancer is genetic, but not all cancer is hereditary. Typical cells turn into cancer by developing genetic changes (mutations) that lead to abnormal growth. These genetic mutations that occur after one is born and throughout the life are known as somatic mutations.

Somatic mutations are typically only found in the tumor or are isolated to one tissue. However, somatic mutations can also be seen at low levels in the blood when cells are shed from the tumor into the blood or lymphatic system (called circulating tumor DNA or ctDNA). In contrast, genetic mutations that are inherited from one's mother or father and are traditionally found in all of the cells throughout the body are called germline mutations.

Lynch syndrome can only be identified through germline genetic testing. However, somatic test results can help guide germline genetic testing. 

- Somatic testing
- Germline testing
- Comparing germline and somatic results
- Laboratory options for tumor profiling
- When to refer to genetic counseling
- Somatic testing literature
- Resources