Fecal occult blood associated with mortality from more than just colorectal cancer

The study looked at all individuals who participated in screening with guaiac fecal occult blood tests in Tayside, Scotland, between 2000 and 2016, with follow-up of up to 16 years.

A positive fecal occult blood test (FOBT) was associated with higher mortality from a range of causes, including circulatory, respiratory, neuropsychological, blood, endocrine, and digestive diseases, not just colorectal cancer, a study found.

All individuals who participated in guaiac FOBT screening in Tayside, Scotland, between 2000 and 2016 (n=134,192) were studied by linking their test results to mortality data, with follow-up of up to 16 years. Results were published by Gut on July 16.

Those with a positive test result (n=2,714) had a higher risk of dying both from colorectal cancer (hazard ratio [HR], 7.79; 95% CI, 6.13 to 9.89; P<0.0001) and causes other than colorectal cancer (HR, 1.58; 95% CI, 1.45 to 1.73; P<0.0001). In addition, a positive FOBT result was significantly associated with increased risk of dying from circulatory disease, respiratory disease, digestive diseases excluding colorectal cancer, neuropsychological disease, blood and endocrine disease, and noncolorectal cancers, the study found.

The authors noted that fecal blood might have potential as a modifiable biomarker for inflammation that could identify lifestyle and prescribing interventions that might reduce the risk of premature death.

“Inflammation as a driver of non-inflammatory disease is well recognized,” the authors wrote. “There is good evidence, for example, that the majority of solid tumours arise against a background of chronic inflammation. It is also well established that systemic inflammation is a risk factor for Alzheimer's disease. In addition, factors predisposing to ill health, such as obesity, sedentary behaviour, smoking, alcohol dependence and a Western diet have been shown to be associated with systemic inflammation.”

An accompanying commentary noted that the surprising findings might be partly explained by the interrelated nature of various diseases, including colorectal cancer, and their risk factors.

“Establishing a [colorectal cancer] screening programme that minimises failures along all the steps in the continuum of interventions, including ensuring appropriate follow-up of abnormal faecal tests, is challenging enough,” the author wrote. “I fear that tasking such programmes, let alone screening in opportunistic settings, with also addressing risk mitigation in multiple disease areas beyond [colorectal cancer] would be too demanding. Possibly a general alert to the patient and her or his primary care physician might be reasonable, but my hope is that primary care physicians would be addressing risk factors for these other diseases already.”