The breast cancer hormone receptor retesting controversy in Newfoundland and Labrador, Canada: lessons for the health system.

The treatment of newly diagnosed breast cancer patients with hormonal treatment is determined by the presence of estrogen receptor and progesterone receptor status in breast cancer. In Newfoundland and Labrador (NL), 425 of 1088 (39.1%) patients who had original "negative" receptor tests conducted between 1997 and 2005, had positive results upon retesting in a specialized laboratory. This commentary addresses (1) the diagnostic utility of estrogen and progesterone testing for breast cancer in general, (2) specific testing problems that occurred in NL, (3) scientific problems associated with retesting, and (4) the impact on public trust and the resulting legal and political responses that occurred as a result of the adverse events associated with false-negative hormone receptor tests. Finally, the lessons learned will be discussed including known high false-negative rates associated with the tests and the bias associated with retesting, the need for quality assurance and national standards, public education, and appropriate communication with patients and the public.