Occult blood in faeces is associated with all-cause and non-colorectal cancer mortality

Abstract

ObjectiveAn association between detectable faecal haemoglobin (f-Hb) and both the risk of death from colorectal cancer (CRC) and all-cause mortality has been reported. We set out to confirm or refute this observation in a UK population and to explore the association between f-Hb, as indicated by a positive guaiac faecal occult blood test (gFOBT) result, and different causes of death.DesignAll individuals (134 192) who participated in gFOBT screening in Tayside, Scotland between 29/03/2000 and 29/03/2016 were studied by linking their test result (positive or negative) with mortality data from the National Records of Scotland database and following to 30/03/2016.ResultsThose with a positive test result (n=2714) had a higher risk of dying than those with a negative result, from CRC: HR 7.79 (95% CI 6.13 to 9.89), p<0.0001, (adjusted for, gender, age, deprivation quintile and medication that can cause bleeding) and all non-CRC causes: HR 1.58 (95% CI 1.45 to 1.73), p<0·0001.· In addition, f-Hb detectable by gFOBT was significantly associated with increased risk of dying from circulatory disease, respiratory disease, digestive diseases (excluding CRC), neuropsychological disease, blood and endocrine disease and non-CRC.ConclusionThe presence of detectable f-Hb is associated with increased risk of death from a wide range of causes.

Transition to quantitative faecal immunochemical testing from guaiac faecal occult blood testing in a fully rolled-out population-based national bowel screening programme

“…However, adenomas are less likely to be visibly bleeding than CRC, and perhaps the relationship between occult colonic bleeding and the detection of adenoma is more subtle than simple bleeding from the lesion. A positive gFOBT result is associated with increased all-cause and non-CRC mortality 27 and one explanation is that occult colonic bleeding reflects systemic inflammation. Since most neoplasia arises in a background of chronic inflammation, 28 it may be that detection of faecal Hb is associated with the detection of adenoma because an inflamed colon has a heightened susceptibility to adenoma formation.…”

Occult blood in faeces: a window into health beyond the colorectum?

“…However, in the study by Chen et al , with median follow-up of 3.5 years and longest follow-up of 8 years, the adjusted HRs for all-cause mortality ranged from 1.15 (95% CI 1.07 to 1.24) to 1.67 (95% CI 1.54 to 2.07) for persons with f-Hb concentrations of 20–49 and ≥450 ng Hb/mL, respectively (trend test p<0.0001), compared with the reference group of 1–19 ng Hb/mL (whose risk did not differ from that of persons with undetectable f-Hb) 2. The current study by Libby et al , with longest follow-up of 16 years, reports an adjusted HR for all-cause non-CRC mortality of 1.58 (95% CI 1.45 to 1.73) for persons with a positive versus a negative gFOBT, as well as increased risk for multiple categories of non-CRC death 1…”

“…Such testing is based on the relatively simple premise that asymptomatic CRCs, and some CRC precursors, may lose small amounts of blood into faeces. The provocative study by Libby et al in Gut ,1 which reports the associations between a positive guaiac faecal occult blood test (gFOBT) result and all-cause as well as non-CRC mortality in the National Health Service Tayside Board area of Scotland, suggests that occult blood in faeces may be telling us more than we might have thought. If the eye is the window to the soul, is a faecal test the window to general health?…”

“…Chen et al first proposed that the impact of f-Hb on all-cause mortality may be mediated through systemic inflammation, acknowledging that the exact mechanisms require further investigation,2 and Libby et al expand on this concept in their discussion 1. It is possible that a single unifying explanation does not exist, and it seems likely that elucidating all relevant mechanisms will not be a quick and simple endeavour.…”

“…We have estimated the average population-wide benefits of CRC screening as 37–51 undiscounted life-days gained per person screened, depending on the strategy, but estimated life expectancy gains actually apply to only the small percentage of the screened population who benefit by avoiding CRC death, with average gains for these persons of 3.5–4.6 undiscounted life-years 9. Libby et al report median (IQR) ages at death of 71 (65–76) years for the gFOBT-negative group versus 70 (64–75) years for the gFOBT-positive group 1. It is not known if this approximate 1 year difference applies specifically to those who might have had CRC death prevented, but it is reassuring that a difference of this magnitude is unlikely to eliminate the potential benefits of CRC screening on life expectancy that are estimated by multiple decision analyses.…”