The BC Cancer Agency is reviewing nearly 200 files of patients because their genetic profiles weren't properly documented.
The patients were assessed by the agency's Hereditary Cancer Program, which reviews people's family histories in an effort to determine their risk of developing an inherited cancer.
Some 188 patients have already been contacted and the agency is still trying to reach four others. The doctors of all affected patients have also been informed.
In a press release, David Weir of the Provincial Health Services Authority said it was taking the matter very seriously and had carried out a review of the circumstances involved.
"The BC Cancer Agency and PHSA apologize and sincerely regret any stress or anxiety this situation may have caused the clients and physicians involved," said Weir.
Weir added that the patients involved are at minimal risk of harm because the program provides counselling and arranges genetic testing, when indicated.
The agency has also introduced additional measures to ensure this type of error does not happen again, and an agency worker involved in the program has been removed from her duties as a result of the faulty filing.
The Cancer Agency is asking patients who were assessed by the program in Vancouver, Surrey or Abbotsford between August and December 2010 and who have not been contacted since to get in touch.