New HER2 testing guidelines

Jcoll4

I found a study that was published may 30, 2018. Titled:

Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer

American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline Focused Update

Question:

Has anyone reviewed and discussed treatment options based on these new guidelines. I fall under category/question 2 within the study.

I am currently being treated with Taxol (received #9 today) and plan to receive a year of Herceptin.

My IHC was 1+ at OSU MED CENTER AND 2+ at Cleveland Clinic. My ISH was >2 but less than 4.0.

My tumor was less than 1cm. No nodes. ER negative. Staged 1a...

Should I be concerned that my treatment plan will change

MelissaDallas

A joint, Focused Update of the "Human Epidermal Growth Factor Receptor 2 (HER2) Testing in Breast Cancer" clinical practice guideline has been developed by an expert panel of pathologists and oncologists and issued by the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) to address new information made available since the guideline's previous update in 2013. Notably, the 2018 Focused Update addresses uncommon clinical scenarios and improves clarity, particularly for infrequent HER2 test results that are of uncertain biologic or clinical significance.

Updated findings of note include:

• Revision of the definition of IHC 2+ (equivocal) to the original FDA-approved criteria.
• Repeat HER2 testing on a surgical specimen if the initially tested core biopsy is negative is no longer stated as mandatory. A new HER2 test may (no longer should) be ordered on the excision specimen on the basis of some criteria (such as tumor grade 3).
• A more rigorous interpretation criteria of the less common patterns that can be seen in about 5% of all cases when HER2 status in breast cancer is evaluated using a dual-probe ISH testing. These cases, described as ISH groups 2 to 4, should now be assessed using a diagnostic approach that includes a concomitant review of the IHC test, which will help the pathologist make a final determination of the tumor specimen as HER2 positive or negative.
• The Expert Panel also preferentially recommends the use of dual-probe instead of single-probe ISH assays, but it recognizes that several single-probe ISH assays have regulatory approval in many parts of the world.

THE COMPLETE FOCUSED UPDATE was published May 30, 2018 as an early online release in Archives of Pathology & Laboratory Medicine.

SpecialK

My take on this is that if your ISH results fall into the greater than 2, less than 4 category you need another confirmatory test using a different testing platform. Because you already had two additional IHC testings performed and your treatment plan was formulated from all results together, I would doubt that your treatment plan would be altered because the ASCO recommendation for additional testing with this type of ISH result was fulfilled.