Test Catalog


ASCO and CAP Guidelines for Human Epidermal Growth Factor Receptor 2 (HER2) Immunohistochemical Testing in Breast Cancer

July 2011

Test Update

Effective January 1, 2012, revised guidelines for immunohistochemical testing (IHC) of HER2 in breast cancer from the American Society of Clinical Oncology (ASCO) and College of American Pathologists (CAP) will be instituted at Mayo Clinic. These revised guidelines are available online at www.asco.org and www.cap.org.

The primary goal of the guidelines is to reduce assay variability and improve accuracy and utility of HER2 testing as predictive markers for breast cancers by offering strategies to optimize assay performance, result interpretation, and result reporting. Among other recommendations, the revised guidelines highlight the critical nature of specimen handling. Preanalytic treatment of the specimen greatly impacts the quality of the specimen and, therefore, the quality of the test result. Specifically, the most significant guideline change is that the time from biopsy or resection of the breast tumor to fixation in 10% neutral buffered formalin fixative should be as short as possible and certainly within 1 hour. Breast needle/core biopsy and excisional specimens must still be fixed in 10% neutral buffered formalin for 6 to 48 hours before processing. Any deviation from this handling can potentially impact the final test results. The revised guidelines also require documentation of time to fixation and the total fixation time.

Following these instructions will optimize your test results:

  • Acquire specimen
  • Within 1 hour of collection, section surgical specimens at 5 mm intervals, fix specimen in 10% neutral buffered formalin
  • Document the time to fixation
  • Fix specimen for no less than 6 hours and no more than 48 hours before processing
  • Document the total fixation time
  • Embed tissue in paraffin

NOTE: Submit only nondecalcified specimens.

We would like to take this opportunity to reassure our clients that Mayo Medical Laboratories routinely participates in proficiency testing surveys and maintains in-house proficiency testing and quality control.

The staff at Mayo Medical Laboratories will continue to monitor the recommendations of ASCO and CAP so we can rapidly respond to process and testing improvements. Meanwhile, it is important to adhere to all specimen collection, preparation, and handling instructions, as delay to fixation, under-fixation, or over-fixation fall outside of ASCO/CAP guidelines and may affect results.


ASCO/CAP Guideline Recommendations for Human Epidermal Growth Factor Receptor 2 Testing and Estrogen and Progesterone Receptors in Breast Cancer. Clinical Notice and Reconciliation Table. Available at: http://www.cap.org/apps/docs/committees/. Updated April 18, 2011.


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