The proposed study aims to evaluate whether the Septin 9 biomarker may be used to supplement the OC-Micro FIT for colorectal cancer screening in such a way as to safely reduce unneeded colonoscopies. The population of interest for this study—those with a positive screening OC-Micro fecal immunochemical test—has a CRC prevalence of approximately 5%. Knowing how well Septin 9 can identify those without cancer prior to colonoscopy is important largely because colonoscopy, even when done diagnostically (e.g., after a positive FIT result), can cause serious complications.