Use of ctDNA for Monitoring of Stage III Colorectal Cancer

Circulating tumor DNA (ctDNA) are small fragments of nucleic acid that originate from
apoptotic or necrotic tumor cell turnover. Characteristic of the malignant process, ctDNA can
be assessed in plasma and offers the potential of a sensitive and specific biomarker for
prognostic information on disease-free or overall survival, and predictive information on
chemotherapy resistance and probability of lack of response to treatment. This study will
evaluate ctDNA as a prognostic marker and as a monitor of disease recurrence in stage III
colorectal cancer (CRC). We will recruit newly diagnosed stage III CRC patients, determine
their tumor mutational profile, and systematically collect high volume (>10 ml), serial
plasma specimens every 3 months for up to 3 years and every 6 months in years 4-5 for ctDNA
and concurrent carcinoembryonic antigen (CEA) measurement. Clinical outcome and survival will
be tracked. The resulting data will permit assessment of ctDNA as a prognostic marker for
disease-free and overall survival and as a monitor of disease recurrence in comparison with
CEA.

Inclusion Criteria:

- Men and women with CRC Stage III A, B, or C

- Age ≥18 years

- Willingness to provide blood samples for research purposes

- Ability to understand written informed consent document, and written informed consent
provided

Exclusion Criteria:

- Blood sampling would compromise patients overall health such as presence of severe
anemia

- Unable to give informed consent