Quebec's College of Physicians is again ordering the re-examination of thousands of mammogram results.
The announcement, made Thursday, comes 10 months after an investigation was launched into potentially erroneous results from several clinics.
At that time, the college ordered the review of 15,000 mammograms after a routine quality control check turned up problems with test analyses.
On Thursday, it ordered the re-examination of 4,500 more tests from three clinics: Radiologie Fabreville in Laval, Radiologie Jean-Talon Belanger and Radiologie Domus Medica.
The college said the latest review is an "additional security measure" and part of the last phase of its investigation.
Any patients involved in the latest re-examination of test results will receive a letter from the college explaining the process.