Detection Rate of Colorectal Cancer or Precancer Adenoma by Colonoscopy After 1, 2, or 3 Positive Results via Fecal Immunochemical Testing

Jill A. Hancock, MLS (ASCP); Glen A. Palmer, PhD, ABN


Lab Med. 2019;50(3):263-267. 

In This Article

Abstract and Introduction


Background: Single-vial fecal immunochemical testing (FIT) is an accepted method of colorectal cancer (CRC) screening. The available 3-vial FIT data set allows for comparison of colonoscopy results using various screening methods.

Objective: To determine the optimal number of vials for a strong FIT-screening program by examining whether using only a single vial impacts the use of colonoscopy for CRC screening.

Methods: Patients were given 3-vial FIT collection kits that were processed with a positive hemoglobin cut-off detection level of 100 ng per mL. If FIT results were positive, colonoscopy testing was performed using standard practices.

Results: Detection of CRC and precursor adenoma was examined in 932 patients, with a positive colonoscopy sensitivity of 56.2% and 3.0% CRC detection after 3-vial FIT; after single-vial screening, those values were 60.9% and 4.7%, respectively.

Conclusions: Prescreening patients with FIT testing before colonoscopy allows colonoscopy testing to be targeted to higher-risk patients. Implementing use of only a single vial from the 3-vial FIT screening kit would reduce the colonoscopy reflex rate, colonoscopy complication numbers, facility costs, and patient distress by more than 40%, compared with 3-vial screening.


Colorectal cancer (CRC) is the second-leading cause of cancer deaths and fourth-leading cause of new cancer cases in the United States, with 50,630 deaths predicted for 2018.[1] The stage of cancer detection is critical to survival rates, with a 5-year survival for localized colon or rectum cancer of 89.9%.[1] Blood in stool can be an indication of CRC or of increased risk of CRC development due to bleeding cancer lesions or precursor polyps/adenomas. It is estimated that 95% of cases of CRC arise from preexisting adenomas; as a result, screening programs are advised to detect CRC at the earliest possible stage.[2]

The median age of CRC cancer diagnosis age is 67 years.[1] The Veterans Health Administration (VHA) National Center for Health Promotion and Disease Prevention recommends men and women aged 50 to 75 years who are at average risk get screened by annual fecal immunochemical testing (FIT), sigmoidoscopy every 5 years, or colonoscopy every 10 years.[3] Regarding the 2016 veteran population, more than 3.6 million veterans in VHA care, and 10.4 million veterans nationally, meet the VHA recommendations to be screened for CRC, based only on age.[3,4]

Colonoscopy is the criterion standard for detection and prevention of CRC and removal of precursor adenoma lesions, However, the limitations due to cost, availability, and patient compliance make FIT an accepted alternative screening method.[5] The FIT method is a widely utilized CRC screening option at the VHA study testing facility. FIT testing detects human hemoglobin (hHb) by immunological latex agglutination in stool specimens, thus eliminating the dietary-restriction limitations of other methods.[6]

The St. Cloud VA Health Care System implemented FIT screening in February 2010. At that time, the VHA Colorectal Cancer Screening directive mandated that VHA facilities utilizing FIT screening test 3 vials.[7] This requirement generated a unique data set. Although the directive was updated in 2014 to allow single-vial FIT screening, the facility maintained 3-vial screening until May 2016.[8]

Throughout the 6-year period, 3-vial FIT screening was performed on approximately 125 patients a month, with an average of 18% having specimens that screen positive in 1, 2, or 3 vials. The VHA directive requires that follow-up action be completed with any FIT vial for which the contents test positive, regardless of the number of vials for which the content screened positive. Colonoscopy was recommended as the standard reflex.[8]

The FIT method utilized in this study is United States Food and Drug Administration (FDA)–approved for single-vial screening; this usage has been adopted as the industry standard in the United States.[9] Within our organization, there was some concern about dropping the FIT screening from 3 vials to a single vial, such as trading sensitivity for cost reduction. This study will help determine the optimal number of vials for a strong FIT-screening program. It was predicted that the detection of CRC or precursor adenomas would be higher with 3-vial screening than single-vial screening and that that higher detection rate would benefit our patient population.