Tissue samples from some breast cancer patients in Newfoundland and Labrador are being retested after one woman received a false-negative report.

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, including survivors. Those who are considered "cancer-free" are tested continually in the years following their therapy.

Zita White

Reliability problems with the test in St. John's were discovered when a patient's condition worsened, despite a negative test result, and the tissue later tested positive.

Zita White of Happy Valley-Goose Bay is one of hundreds of women who are waiting to find out if they received the correct treatment.

"If I had tested positive, I would have been given the drug tamoxifen, which would have greatly lowered my chance for recurrence," said White, who believes on the basis of past tests that she is cancer-free.

Officials at the St. John's lab acknowledged the problem, but they don't yet know what went wrong.

"There's 40 steps in that process," said Bob Williams, a vice-president at the Eastern Heatlh regional authority. "Any problem in any one step can cause a problem with the testing results."

Problems with the test are not new. Medical literature shows test results have varied widely between labs in Europe. Williams said its prompted the lab to take another look at their testing procedure.

Dr. Brian Hewlitt

Canada lacks a national standard body for the tests, said Dr. Brian Hewlitt, an expert in medical technology. He said labs across the country should take a look at what they're doing to make sure they are getting it right.

"I think the laboratories performing the testing are duty-bound to do some peer comparison, to take their material and have it tested in another centre and compare the results," said Hewlitt.

"On the basis of that, then you may or may not wish to become severely worried."

Breast cancer patients in Newfoundland are scrambling for answers.

"There is absolutely no doubt that there is a group of women out there that didn't get proper treatment, and that could have very dire consequences," said Peter Dawe, director of the Newfoundland and Labrador chapter of the Canadian Cancer Society.