A recent Korean study finds that patients with a positive FIT should be offered a new colonoscopy, even if the last colonoscopy was performed less than 10 years ago. Regardless of the time elapsed since the previous colonoscopy, the detection rate of both CRC and ACRN was significantly higher among FIT-positive than among FIT-negative subjects.
The Korean study (Source 1) supports the recommendation of the US Multi-Society Task Force on Colorectal Cancer (CRC) (Source 2). According to this study, patients with a positive Fecal Immunochemistry Test (FIT) should be offered a new colonoscopy, even if the last colonoscopy was performed less than 10 years ago. The Korean study showed that CRC and Advanced Colo-Rectal Neoplasia (ACRN) were not uncommon among hospital patients. Regardless of the time elapsed since the previous colonoscopy, the detection rate of both CRC and ACRN was significantly higher among FIT-positive subjects than among FIT-negative subjects. The researchers led by Nam Hee Kim of Kangbuk Samsung Hospital in Seoul, Korea, therefore considered the recommendation of the Multi-Society Task Force on colorectal cancer screening, which had hitherto been essentially based on expert opinion but not on study data, to be confirmed.
For their study, the scientists drew on participants in Korea's general colorectal cancer screening program, which enables all Koreans aged 50 and over to receive an annual FIT. Among the 52,376 patients at Kangbuk Samsung Hospital who underwent a FIT between January 2013 and July 2017, the authors identified 3,229 (6.2%) with positive test results. Of these, 2,362 (73.1%) ultimately participated in a colonoscopy. The study participants were divided into three groups according to the time interval of their previous colonoscopy: 0 - 3 years (n = 514; 23.1%), 3 - 10 years (n = 427; 19.2%) and > 10 years (n = 1,287; 57.8%). All study participants had to be free of intestinal complaints at inclusion and were not allowed to suffer from a chronic inflammatory bowel disease in order to largely exclude falsifications of the FIT due to non-neoplasm-related bleeding.
In parallel, colonoscopies were performed on 6,525 patients of the 49,147 patients with a negative FIT, of whom 6,135 participants served as comparison groups. The study population had an average age of 63.4 ± 8.1 years and was 52.6% male.
The prevalence of ACRN among the colonoscopy participants was 10.9%, 12.6% and 26.0% in the three groups with increasing time distance from the previous colonoscopy. For a CRC the prevalence was 2.1%, 1.6%, and 7.2%.
There were significant differences between FIT-positive and FIT-negative participants. Thus, the frequency of each form of colorectal neoplasia among FIT-positive participants was 61.3% compared to 51.8% among FIT-negative participants (p < 0.001). The frequency was also significantly different for ACRN (20.0% versus 10.3%, p < 0.001) and CRC (5.0% versus 1.9%, p < 0.001). In addition, patients whose colonoscopy was more than 10 years old or who had never had a colonoscopy before had a significantly increased risk of ACRN (odds ratio [OR] 3.63, 95% CI; 2.48 - 5.31) or CRC (OR 3.66; 95% CI, 1.74 - 7.73). However, there was no significant difference either for ACRN or for CRC between patients whose colonoscopy had taken place less than 3 years ago and those whose colonoscopy had taken place 3 to 10 years ago.
Study participants in the group whose last colonoscopy was less than 3 years ago had a CRC in 2.1% and an ACRN in 10.9%. Statistically, this proportion of positive diagnoses did not differ from that of patients whose previous colonoscopy was 3 to 10 years old. However, there were significant differences in the proportion of positive diagnoses in patients whose last colonoscopy was more than 10 years ago. Thus, the study confirmed the importance of the recommendation to repeat a colonoscopy every ten years. However, this recommendation may have to be modified in the case of a positive FIT and the distance between the colonoscopies shortened. In principle, every patient with a positive FIT should be offered a new colonoscopy.
Finally, the study authors discuss the safer detection of blood in stool by FIT compared to the less meaningful Guaiac-based fecal occult blood testing (gFOBT). They suspect that the findings of a study by Liu et al. (Source 3), which contradict their own results, may be due to the use of the less specific gFOBT instead of the FIT.
Sources:
1. Kim NH, et al. Yield of repeat colonoscopy in asymptomatic individuals with a positive fecal immunochemical test and recent colonoscopy. Gastrointestinal Endoscopy 2019; pii: S0016-5107(19)30025-2. https://www.ncbi.nlm.nih.gov/pubmed/30684602.
2. Robertson DJ, et al. Recommendations on Fecal Immunochemical Testing to Screen for Colorectal Neoplasia: A Consensus Statement by the US Multi-Society Task Force on Colorectal Cancer. Gastroenterology 2017; 152: 1217-37.e3. https://www.ncbi.nlm.nih.gov/pubmed/27769517.
3. Liu J, et al. Annual Fecal Occult Blood Testing can be Safely Suspended for up to 5 Years After a Negative Colonoscopy in Asymptomatic Average-Risk Patients. On the J Gastroenterol 2015; 110: 1355-8. https://www.ncbi.nlm.nih.gov/pubmed/26238157