Long-term risk of colorectal cancer after negative colonoscopy in a Danish gFOBT screening cohort

Abstract

Faecal occult blood test (FOBT) screening for colorectal cancer (CRC) is implemented in several countries. Approximately half of all screen positive persons have negative colonoscopy, but consensus is lacking on how these persons should be followed up. Health authorities in Denmark and The Netherlands recommend suspending screening for 8-10 years, while patients in UK are invited to screening after 2 years. In this cohort-study, we followed 166,277 individuals invited to FOBT-screening in 2005-2006 and a reference group comprising the remaining 1,240,348 Danes of the same age. We linked Danish population and health service registers to obtain information about colonoscopy outcome and incident CRC. We estimated CRC risk by colonoscopy outcome (adenoma, other colorectal pathology or negative colonoscopy) for the reference group, the screening group, and subgroups. Persons with positive screening FOBT followed by negative colonoscopy had the same long-term CRC risk as persons with adenoma detected due to a positive screening FOBT (aHR 1.33, 95% CI: 0.65-2.71). We found no difference in the long-term CRC risk between persons with negative colonoscopy after a positive FOBT screening test and the unscreened reference population (aHR 1.05, 95% CI: 0.62-1.78). Since FOBT screen positive persons in our study remained at average risk of CRC despite of a negative index colonoscopy, we question the safety of suspending FOBT screening for this group. It needs to be monitored whether recent efforts to improve colonoscopy quality have been successful in ensuring low CRC risk after negative colonoscopy also in FOBT positive persons.

Gaitada Gizli Kan Pozitifliği Nedeniyle Kolonoskopi Yapılanlarda Kolorektal Malignite Sıklığı

“…Danimarka ve Hollanda'da 8-10 yıl arayla tarama yapmak önerilse de İngiltere'de 2 yılda bir tarama yapılması önerilmiştir. Aynı çalışmada GGK pozitif olan 26.123 kişinin alındığı kolonoskopik taramadaki bireylerin yaklaşık %5'inde kolorektal kanser, %15'inde adenom tespit edilmiş (14). Paimela ve arkadaşlarının yaptıkları çalışmada GGK pozitif tespit edilen hastalar arasında invaziv kolorektal kanser tespit oranı %8,2, adenom ve kolorektal mukozal invazyon gösteren kanser oranı ise %39,7 olarak tespit edilmişti (15).…”

Yield of screening and diagnostic colonoscopy for polyp and cancer detection

“…[31] Tumor detection rates are lower in patients with abdominal pain than in those with iron deficiency anemia and rectal bleeding. [32][33][34] In the present study, rectal bleeding and constipation were the leading indications for colonoscopy, with the two indications accounting for the two-thirds of the total. Although not to a statistically significant degree, GIS bleeding and anemia were the most common indications among those identified with cancer.…”

Colorectal cancer after negative colonoscopy in fecal immunochemical test-positive participants from a colorectal cancer screening program

“…The incidence of CRC after a negative colonoscopy in the context of population organized FOBT-based screening programs has only been reported in two studies that used guaiac-FOBT. A Danish study reported 14 CRCs out of 771 positive guaiac-FOBT followed by a negative colonoscopy (1.8 %) after 8 years of follow-up 11 . In that study, the individuals with positive FOBT and subsequent negative colonoscopy had the same long-term CRC risk as individuals with positive FOBT and adenomas and as the unscreened reference population 11 .…”

“…A Danish study reported 14 CRCs out of 771 positive guaiac-FOBT followed by a negative colonoscopy (1.8 %) after 8 years of follow-up 11 . In that study, the individuals with positive FOBT and subsequent negative colonoscopy had the same long-term CRC risk as individuals with positive FOBT and adenomas and as the unscreened reference population 11 . Based on these results, the authors suggested that a 10-year interval of screening may not be safe.…”

“…Fecal immunochemical tests (FIT) are immunoassays specific for intact human hemoglobin 9 , recommended as first choice over guaiac-FOBT given their higher specificity for human blood superiority and better sensitivity for the detection of advanced colorectal neoplasia 10 . In the scenario of organized FIT-based screening programs, around 20 – 30 % of individuals have a positive test followed by a negative colonoscopy 11 . These individuals are considered at null risk for CRC for the following 10 years 12 .…”