Abstract

Colorectal cancer is the third most common cancer in the world and ranks fourth among the causes of death. In the United States, approximately 150,000 new colorectal cancers are diagnosed annually and approximately 50,000 people die annually. When the patients are diagnosed, 90% of them are seen with regional tumors and 10% are spread to distant organs. This shows that early diagnosis and treatment methods should be developed. In order to significantly improve the follow-up of colorectal cancer patients, there is a need for non-invasive tools that enable the prognosis to be confirmed at the time of diagnosis and for early detection of recurrence. Multiple genetic and epigenetic changes are effective in the development and development of colorectal cancer. Significant molecular biomarkers can be identified by detection of these genetic changes by tumor DNA in different body fluids and by molecular changes in DNA. "Liquid biopsy" analysis using circulating tumor cells or plasma-derived circulating tumor DNA provides a non-invasive alternative to tissue biopsies and reaches an important place in future biomarkers.