'Invisible' Stool Blood Could Indicate Risk of Dying from All Causes

Invisible blood in the stool puts a person at a heightened risk of dying from circulatory, respiratory, digestive, blood, hormone and neuropsychological diseases, as well as bowel cancer and other types of cancer, reveals research published online in the journal Gut. Unseen or ‘invisible’ blood, otherwise called occult blood is named so as it cannot be seen with the naked eye. It can be detected using the fecal occult blood test (FOBT) and is currently used to screen for bowel cancer or colorectal cancer (cancer that starts in the colon (large bowel) or back passage (rectum)) or its precursor, polyps, in older people.

The FOBT checks for the presence of blood in a sample of stool or feces. Blood in the stool indicates a possibility of bleeding in the digestive tract that could be caused by hemorrhoids, polyps, ulcers, colitis or colorectal cancer that affects the colon or rectum.

Previous research has indicated that blood in the stool might predict life expectancy irrespective of whether a person has bowel cancer or not. But the research did not account for other potentially influential factors, including drugs like aspirin that might induce internal bleeding.

Study Design and Results

The researchers examined data of nearly 134,000 people, aged between 50 and 74 obtained from linked prescribing, bowel cancer screening, and death registry in Tayside, Scotland, from March 2000 to the end of March 2016. They tracked their survival from the date of the first test until death or the end of March 2016, whichever came first.

• 2714 (just over 2%) tested positive for occult stool blood while 131,207 people tested negative during this period.
• Older people and those with increasing levels of deprivation, and belonging to the male gender were associated with a higher likelihood of a positive test result.
• Aspirin or other drugs that boost the risk of digestive tract bleeds were also influencing a positive test result.
• People who showed a positive FOBT result were nearly eight times as likely to die of bowel cancer compared to those who tested negative, after normalizing for gender, age, deprivation, and drug treatment.
• The most surprising result was that a positive FOBT result was also associated with a 58 percent heightened risk of death from all other causes like cardiovascular, respiratory, digestive tract, neuropsychological (how the brain correlates with the mind), blood disorders, and hormone imbalances, as well as other types of cancer, after normalizing for potentially influential factors.

The research team points out that even after adjusting for risk factors like older age, male gender, and increasing levels of deprivation, a positive FOBT result was still strongly associated with early death.

"Although increased [unseen stool blood] cannot be a cause of death, it may reflect the reason why male gender, age and deprivation are such strong risk factors," they suggest.

The authors speculate that generalized inflammation that takes the form of gut inflammation and bleeding may be a suspect, as most solid cancers and Alzheimer's disease have been proved to develop against a background of chronic/systemic inflammation.

A positive FOBT result could be used in future to alert participants of a bowel cancer screening programme without the disease (which amounts to around half of those who test positive in the screening) that the test puts them at risk of other potentially life-limiting illness, and that they need a healthier lifestyle and/or preventive drug treatment.

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Professor Uri Ladabaum of Stanford University School of Medicine says, "Perhaps more importantly, if occult blood in feces is a predictor of life expectancy and multiple [non-bowel cancer] causes of death, the inevitable next questions concern the implications for organized [bowel cancer] screening programs or opportunistic [bowel cancer] screening."

Reference:

1. Fecal Occult Blood Test (FOBT) - (https://medlineplus.gov/labtests/fecaloccultbloodtestfobt.html)

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Source-Medindia