More than 100 patients in Newfoundland and Labrador failed to receive a hormone treatment for breast cancer because of a screening problem, health officials said Monday.

The patients were initially disqualified from treatment because of problems with the tests used to determine eligibility.

After tissue samples were retested, 117 patients were started on the hormone treatment they should have received earlier.

Since last year, Toronto's Mount Sinai Hospital has been retesting samples from about 900 patients in St. John's who were initially tested between 1997 and 2005. As a result of the retesting, 117 patients who had been denied treatment earlier are now receiving it.

The hormone receptor test shows if cancer cells respond to hormones. If the results are positive, patients are usually treated with the hormone therapy tamoxifen.

The tests are given to women who have been treated for breast cancer in the past. Those who are considered "cancer-free" are still tested frequently in the years following their therapy.

Because of a potential lawsuit, provincial health officials refused to explain if the discrepancy resulted from human error or from new methods of interpreting test results.

Officials also would not say if any patients who were mistakenly denied hormone treatment had died, or were needlessly given mastectomies when they could have been treated with drugs.

"Not receiving this treatment could very well mean a life and death issue for people going through the process," said Peter Dawe, director of the Newfoundland and Labrador chapter of the Canadian Cancer Society.

The lack of disclosure raises questions, said Dawe, about what the problem is and how it can be fixed.

Health officials in Newfoundland and Labrador hope to resume their own hormone testing in the near future, though they can't say when.