Dr. Bernard Badley, medical director of the province's Colon Cancer Prevention Program, said Thursday that a monitoring system that tracks the kits discovered about three months ago that positive test results had doubled.
He said the manufacturer looked into the issue after Badley's group notified them and determined that the chemical agent used to detect elevated levels of blood in samples was too sensitive.
Previously, Badley said about four or five people out of every 100 who took the test were found to have an abnormal amount of blood in their stool sample on average.
But the number of abnormal results doubled to about 10 out of 100 a few months ago, leading Badley to examine their own processes and then contact the manufacturer to have them look into the issue.
"It was twice as sensitive," he said of the chemical agent. "What this means is that some people through our program would have been advised to have a colonoscopy that wouldn't have been advised to do so (before)."
He stressed that there is no health risk associated with the test results, other than the inconvenience of having someone undergo a colonoscopy who may not have been advised to have one when the testing process was working properly.
Erika Nicholson, director of Cancer Prevention and Early Detection, said about 900 people could have received abnormal results in that three-month period. She said health district screening nurses would be informing people of the problem, but was still suggesting that they undergo a colonoscopy.
Mary Luthy, a spokeswoman for Beckman Coulter, the company that manufacturers the agent, said they are investigating the matter but that the product is "meeting its release specifications."
Badley said the home screening tests won't be mailed out until the supplier has fixed the problem, which he expects will be done in six months.
The screening tests, which were introduced in the province about four years ago, look for hidden blood in stool which may be a sign of cancer.
Badley explained that colon cancer develops from abnormal growths in the colon, called polyps. As they increase in size, they can bleed. If the amount of blood is abnormally high, it can be a sign that cancer could develop and a colonoscopy is used to identify the source of the blood loss.
The home tests go out to people between the age of 50 and 74 and it's recommended it be done every two years. Badley said people can still get tested by their doctor while the home tests are suspended.
Nicholson said about 2,000 kits would normally go out a week and about 30 per cent of those are returned.
Note to readers: This is a corrected story. A previous version said in the headline that the program has been halted after false test results.