Colorectal cancer mortality 10 years after a single round of guaiac faecal occult blood test (gFOBT) screening: experiences from a Danish screening cohort

Abstract

BackgroundIn Denmark, colorectal cancer (CRC) is the third most frequent cancer. Randomised trials have shown that guaiac faecal occult blood test (gFOBT) screening can reduce CRC mortality, but a recent large randomised study from Finland did not find any effect. A feasibility study was carried out in Denmark in 2005–2006 where residents aged 50–74 years in 2 Danish counties were invited once to participate in gFOBT screening. We used the unique Danish registers to assess the impact of gFOBT screening in this group on CRC incidence and mortality.MethodsIn this cohort study, we followed a group comprising 166 277 individuals invited to screening and a reference group comprising the remaining 1 240 348 Danes of the same age. We linked the Danish population and health service registers to obtain information about colonoscopies, polypectomies, incident CRC and cause of death.ResultsAfter a median follow-up time of 8.9 years, the CRC mortality was significantly lower in the screening group than in the reference group with an adjusted HR (aHR) of 0.92 (95% CI 0.86 to 0.99), while the aHR for all-cause mortality was 0.95 (95% CI 0.94 to 0.96). For screening participants, the aHR for CRC mortality and all-cause mortality was 0.72 (0.64 to 0.80) and 0.59 (0.57 to 0.60), respectively.ConclusionsAbout 10 years after a single round of gFOBT screening, we found a significant 8% deficit in CRC mortality in the screening group compared with other Danes. We found almost the same deficit in all-cause mortality, and on this basis, it is not possible to conclude that one screening round had an effect on CRC mortality. Our study indicated that close monitoring of the outcome of CRC screening is warranted.

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

“…As we have reported elsewhere, the study population invited for the pilot screening program had a 5% deficit, and the participants a 41% deficit, in all‐cause mortality as compared with the reference population . We were not able to control for these pre‐existing differences in health status.…”

Impact of colorectal cancer screening on cancer-specific mortality in Europe: A systematic review

“…Effectiveness of gFOBT was investigated using various study designs and target ages: screening was offered to individuals between the ages 45 and 74 or 75 years in two RCTs [22,23] and a population-based cohort study [24], between the ages 50 and 63e74 years in three cohort studies [9,25,26], between the ages 60 and 64e69 years in two RCTs [7,27] and for anyone older than 40 years in two caseecontrol studies [28,29]. Despite these differences, the estimated impact of gFOBT screening did not vary substantially across studies.…”

The IARC Perspective on Colorectal Cancer Screening

“…These studies included 5 randomized trials that were performed in North America or Western Europe [16][17][18][19][20] and 10 observational studies conducted in screening settings that were performed in different geographic regions. [21][22][23][24][25][26][27][28][29][30] In these studies, the investigators performed guaiac testing either without rehydration or with hydration, with the latter test having a higher sensitivity (Table 1).…”