The province's College of Physicians said patients who received the substandard procedure have been contacted and the doctor was sanctioned.
A total of 684 patients at Lakeshore will have to be screened for colon cancer again.
An internal audit of one doctor's test results in the last three years revealed inconsistencies in tests described as "incomplete." The hospital is erring on the side of caution because it is unsure whether the doctor in question had failed to complete his reports or actually performed poor tests.
"He is limited, he has no more right to do colonoscopies. His exercise is limited to minor surgeries that don't need sedation like colonoscopies," said Yves Robert, spokesman for the College of Physicians.
Hospital officials said they have contacted the patients who are affected.