Context: Estrogen receptor and progesterone receptor status is assessed on all newly diagnosed, invasive breast carcinomas and in recurrences to determine patient eligibility for hormonal therapy, but 10% to 20% of estrogen receptor and progesterone receptor test results are discordant when tested in multiple laboratories.
Objective: To define the analytic (technical) validation requirements for estrogen receptor and progesterone receptor immunohistochemistry assays used to select patients for hormonal therapy.
Data sources: Literature review and expert consensus.
Conclusions: A standardized process for initial test validation is described. We believe adoption of this process will improve the accuracy of hormone-receptor testing, reduce interlaboratory variation, and minimize false-positive and false-negative results. Required ongoing assay assessment procedures are also described.