Breast Cancer Patients Miss Out on Appropriate Treatment Thanks to Inaccurate Tests

Faulty cancer tests might be keeping some <"">breast cancer patients from getting appropriate treatment.  The American Cancer Society expected nearly 180,000 patients to be diagnosed with invasive breast cancer in the U.S. in 2007.  Tests help determine whether women with invasive breast cancer receive drugs such as Genentech Inc.’s Herceptin; GlaxoSmithKline PLC’s Tykerb and a number of anti-hormone medications, including the generic tamoxifen; and newer treatments such as AstraZenecaPLC’s Arimidex and Faslodex.  Several major private insurers, including UnitedHealth, Aetna Inc., and WellPoint Inc., say they pay for second-opinion tests but few doctors order them.

Tests relating anti-hormone drugs require pathologists to make judgment calls.  One test examines whether cells have too much Her-2 protein; Herceptin targets and destroys those cells.  Another checks for cell proteins serving as receptors for estrogen or progesterone—which can help tumors grow.  If positive, doctors often prescribe drugs such as tamoxifen to suppress or block hormones.  A 2006 study on Her-2 tests found 14-16% of those judged positive for Her-2 were negative; 18-23% judged negative were positive.  After problems with hormone testing at a Newfoundland lab, retesting of tissue from 763 patients with negative results revealed 317—nearly half—were positive.  In another study, 70% of 105 patients judged negative were positive when retested.  “If we tried to market pregnancy tests with this rate of inaccuracy, they would be taken off the market,” says Allen Gown, chief pathologist of Seattle’s PhenoPath Laboratories.

These concerns could add momentum to efforts by Congress and consumer groups pushing for increased lab testing oversight.  Every prescription drug must receive Food and Drug Administration (FDA) approval, but labs can develop and perform their own tests.  The FDA approves certain testing kits, but labs can adjust procedures without sign-off.  Rolf Ehrnstrom, corporate vice president of research and development at Dako Denmark A/S—maker of diagnostic tests and an equipment manufacturer that sells Her-2 and hormone-receptor test kits—said if labs follow testing recommendations, “you have a much more standardized way of doing it,” adding, “We need to standardize and make more quality-assurance throughout the labs.”  Barry M. Straube, chief medical officer at the Centers for Medicare and Medicaid Services, the U.S. agency that regulates labs, says his agency is examining tougher quality control.  Labs must pass proficiency checks on only 83 tests from a 1992 list that doesn’t include the breast cancer tests or dozens of others developed more recently.

The College of American Pathologists plans to require proficiency checks from the labs it oversees if they want to offer the Her-2 test.  The college and the American Society of Clinical Oncology estimated 20% of Her-2 testing may be inaccurate and pathologists and oncologists say labs inexperienced in a particular test may not understand how small procedure changes affect results.  Pathologists at Intermountain Healthcare found results on hormone receptor testing varied based on the day of the week a patient had surgery because when tissue was refrigerated or kept in a preservative over the weekend the results were different from tissue examined quickly.

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