乌鸦传媒

Abnormal results of guaiac fecal occult blood testing (FOBT) may flag a higher mortality risk that extends beyond death from colorectal cancer, a Scottish study showed.

The study, which had as much as 16 years of follow-up not only found a higher death rate from colorectal cancer in those with positive FOBT results (adjusted HR 7.79, 95% CI 6.13-9.89), but also a higher death rate from all other causes (adjusted HR 1.58, 95% CI 1.45-1.73), according to Robert Steele, MD, of Ninewells Hospital and Medical School in Scotland, and colleagues.

These other causes include circulatory disease, respiratory disease, digestive diseases excluding colorectal cancer, neuropsychological disease, and blood and endocrine disease, the investigators found in their study .

People undergoing FOBT in 2000-2016 in Tayside, Scotland, formed the basis of the study (n=134,192). Steele's group linked each person's screening result to the National Records of Scotland database.

"It is of particular interest that deaths from circulatory diseases, respiratory diseases and neuropsychological disorders were associated with the presence of hemoglobin in faeces and, although some non-colorectal cancers may bleed into the gut, for example, stomach and pancreatic cancers, most do not," the investigators noted.

"It is long been assumed that colonic adenomas are detected by FOBT screening because they bleed but, in contrast to invasive cancer, it is rare to see overt bleeding from adenomas at colonoscopy with currently available endoscopic techniques. Therefore, it may be that the increased risk of colonic adenoma in the FOBT positive population is due to generalised colonic inflammation rather than bleeding from the adenomas themselves."

Abnormal FOBT results were more likely among men and older individuals, as well as those prescribed aspirin or any medicine that increases risk of bleeding.

Fecal hemoglobin might have potential as a marker of general disease, Steele and colleagues suggested.

However, they acknowledged that the guaiac test is based on a peroxidase reaction and doesn't quantify the amount of blood in stool. Their study was also weakened by their reliance on prescription data that did not take into account the patients' actual medication adherence.

"[The authors] suggest that such results might be used to alert invitees to the risk of other disease, possibly leading to interventions based on diet, weight management, exercise or medications. I suspect that an abnormal faecal occult blood test is rarely the exclusive piece of information that would trigger such recommendations for a given patient," commented Uri Ladabaum, MD, of Stanford University School of Medicine in California.

"Occult blood in feces may be telling us about health beyond the colorectum. However, it seems likely that what it tells us about non-CRC [colorectal cancer] risk might be gleaned also from other pieces of information about a patient," he wrote in an . "For now, I believe that our enthusiasm for the established CRC screening methods should not be affected, and that the focus after an abnormal fecal occult blood test should be to ensure prompt delivery of a follow-up colonoscopy."