OWEN SOUND, Ont. — An Owen Sound hospital says it is notifying patients whose diagnosis or treatment might have been affected by errors discovered in the work of one of its three pathologists.

Grey Bruce Health Services says a routine quality assurance test in February identified an error in one of Dr. Barry Sawka's findings.

An internal review of 600 of Sawka's most recent cases found an error rate of six per cent.

The hospital says in a release Wednesday that the normal error rate for pathologists is about one per cent.

The review also found the errors have the potential to have altered the further investigation or treatment of patients and include missing cancer diagnoses.

Sawka voluntarily withdrew from practice in February.

"When further investigation indicated the error might not be an isolated one, Dr. Sawka was asked to voluntarily withdraw from practice immediately, and he did so," the release said.

"Grey Bruce Health Services offers its sincere apologies to patients and their families who have been affected by these errors or who will be anxious until they know whether or how they have been affected," said hospital president Pat Campbell. "We will work as quickly as possible to identify any other cases where errors may have been made."

The hospital said it will contact patients whose cases were among the 600 involved in the internal review. Necessary courses of action will be determined by the patients' physician or surgeon.

Sawka had been a pathologist at the hospital since 1994, evaluating approximately 3,000 cases a year for a total of about 40,000 cases.

Specimens from all those cases remain available for re-evaluation, the hospital said.