After an erroneous interpretation of a pathology test for breast cancer markers was discovered two years ago, Quebec’s College of Physicians began a random quality control review. The results show a significant number of errors which all trace back to a single radiologist. The doctor, whose name has not been released, worked at three clinics: Radiologie Jean-Talon Bélanger and Radiologie Domus Médica in Montreal, and Radiologie Fabreville in Laval. Now, 15,000 mammograms will be reviewed over the next six months. Patients won’t be required to undergo new mammograms, but the College admits that the discovery of false negatives and false positives is “likely.” The College said that the radiologist in question was skilled at analyzing all diagnostic scans except mammograms, so only those will be checked. Recent quality control reviews in St. John’s, Nfld. and Windsor, Ont. also found large numbers of mistakes attributable to single incompetent doctors.