Estrogen and Progesterone Receptor Testing in Breast Cancer

Publication Date: January 13, 2020

Key Points

Key Points

The College of American Pathologists (CAP) and the American Society of Clinical Oncology (ASCO) convened an expert panel to consider new evidence or emerging data that might prompt changes to clinical practices that were established with the 2010 ASCO/CAP Guideline Recommendations for Immunohistochemical (IHC) Testing of Estrogen and Progesterone Receptors (ER/PgR) in Breast Cancer.

A well-performed ER/PgR assay identifies which patients could benefit from to endocrine therapy as treatment after a diagnosis of breast cancer. Additionally, hormone receptor status can be valuable more broadly for tumor classification and other factors that inform treatment.

Globally, more than 1 million women are being diagnosed annually with breast cancer and receptor testing conducted on these biopsies typically discern that approximately 8 in 10 of these women have ER positive breast cancer.

The new guidance reaffirms many of the 2010 recommendations, including that patients with breast cancers having 1–100% ER expression be considered ER positive for the purpose of endocrine therapy decisions. However, new reporting recommendations are made for cases with 1–10% ER expression to acknowledge the more limited data on endocrine responsiveness in this group and overlapping features with ER negative cancers.

The update also has a new recommendation for labs to establish a specific standard operating procedure to ensure the validity of low positive (1–10%) or negative (0 or <1%) interpretations and results. Correlation of ER staining with the histologic features (as well as attention to other standard quality control measures) is also recommended and unusual/discordant results worked up.

The utility of PgR-positive population, but testing using similar principles to ER testing is still recommended for invasive cancers.

Additionally, the updated draft now recommends ER testing for patients diagnosed with ductal carcinoma in situ, but PgR testing is optional.

Diagnosis

...iagnos...

...lgorithm for ER/PgR testingSamples...


...esting conditions (no change)Large, (preferably...


...l tissue handling requirements (no cha...


...validation procedures (change anticipated)...


...nternal QA proceduresOngoing quality control and...


...external proficiency assessmentThe lab...


...l laboratory accreditationOn-site ins...


...ories should include ongoing quali...


...tation of any ER result should include ev...


...ories should establish and follow a s...


...of internal controls should be reported for cases...


...lidated IHC is the recommended stan...


...n cases of newly diagnosed DCIS (without as...


...e 1. Invasive Breast Cancer Histopatholo...


...itional Recommended Reporting Comme...


...commendations for Scoring (Readout) an...


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...legend: Examples of invasive cancers with v...


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...External ControlsFigure legend: Optimal...