This is a prospective observational cohort study conducted at a tertiary care endoscopy unit in Sohag Government. Adult patients aged 40 to 75 years who are referred for diagnostic or screening colonoscopy will be invited to participate.
All eligible participants will provide a stool sample for quantitative fecal immunochemical testing (qFIT) prior to bowel preparation. Fecal hemoglobin concentration will be measured using a quantitative FIT assay and expressed as micrograms of hemoglobin per gram of stool.
All participants will subsequently undergo colonoscopy as part of routine clinical care. Colonoscopic findings will be recorded, including lesion presence, anatomical location (proximal colon, distal colon, or rectum), size, and morphology. Biopsy or polypectomy specimens will be examined histopathologically to confirm colorectal cancer, advanced adenomas, or sessile serrated lesions.
The diagnostic performance of qFIT will be evaluated by calculating sensitivity, specificity, positive predictive value, and negative predictive value for detection of colorectal cancer and precancerous lesions. Receiver operating characteristic (ROC) curve analysis will be used to determine optimal qFIT cutoff values according to lesion type and anatomical location. Associations between qFIT levels and lesion characteristics will also be analyzed.
