Breast cancer: updated ASCO/CAP guideline creates new category for low ER+ tumors

  • Allison KH & al.
  • J Clin Oncol
  • 13 Jan 2020

  • curated by Miriam Davis, PhD
  • Univadis Clinical Summaries
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Takeaway

  • Breast tumors with 1%-10% estrogen receptor (ER)-positive staining should be newly categorized as "ER Low Positive," according to an updated guideline by an international panel of the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP).
  • The new category should be accompanied by a comment that "limited data ... suggest possible benefit" of endocrine treatment.
  • No similar change was recommended for the progesterone receptor (PR).
  • The new guidelines carry 3 other multipart recommendations.

Why this matters

  • More than 1 million women per year worldwide are tested for this type of breast cancer.
  • The purpose of the new ER Low Positive category and other categories is to promote endocrine therapy, assist in prognostication, and be a diagnostic aid in metastatic breast cancer.

Study design

  • Recommendations developed by a review of the medical literature by an international multidisciplinary panel.
  • Funding: ASCO.

Other highlights

  • Clinicians should be able to discuss with patients the limited data behind the ER Low Positive category.
  • Patients with ductal carcinoma in situ should be tested for ER, whereas testing for PR should be optional.
  • A sample is considered ER− when
  • Reporting of initial low to no ER immunoreactivity should include a new laboratory-specific standard operating procedure to confirm/adjudicate results.