Table I.

Eligibility criteria for the selection and exclusion of study subjects.

Clinicopathological characteristics
General inclusion criteria
1. Age ≥18 years and ≤80 years
2. Not currently residing in an institution, such as a nursing home or shelter
3. Not severely ill in the intensive care unit
4. With the capability to give informed consent
5. Encountered between September 2013 and March 2015
Healthy individuals (plasma control group)
1. Underwent the medical check-up in King Khalid University Hospital
2. Asymptomatic and apparently healthy without a previous history of cancer
3. Confirmed healthy condition without malignancy in the physical examinations
4. No system infection (lung, gastrointestinal or urinary tract)
Colorectal cancer patients (CRC group)
1. Underwent colonoscopy biopsy and colorectal surgical resections
2. Diagnosed by 2 experienced pathologists
4. No pre-operative chemotherapy and radiotherapy