This is an original JCO publication from 2013. Please visit the JCO website to access the full article.
Antonio C. Wolff,* M. Elizabeth H. Hammond,* David G. Hicks,* Mitch Dowsett,* Lisa M. McShane,* Kimberly H. Allison, Donald C. Allred, John M.S. Bartlett, Michael Bilous, Patrick Fitzgibbons, Wedad Hanna, Robert B. Jenkins, Pamela B. Mangu, Soonmyung Paik, Edith A. Perez, Michael F. Press, Patricia A. Spears, Gail H. Vance, Giuseppe Viale, and Daniel F. Hayes*
*Steering Committee member
This guideline is currently in the process of being updated.
Notice: Both ASCO and CAP are committed to maintaining and updating guidelines as new evidence becomes available. ASCO and CAP will reconvene the HER2 Testing Update Committee to develop and publish a focused update on recent issues brought forth. Further information may be found in the March 9th early release of the letter to the editor and reply in the Journal of Clinical Oncology. A separate editorial will be forthcoming in the Archives of Pathology and Laboratory Medicine.
Key Recommendations for Oncologists
Key Recommendations for Pathologists
Specimens to be tested
All primary breast cancer specimens and metastases should have at least one HER2 test performed
All newly diagnosed patients with breast cancer must have a HER2 test performed. Patients who then develop metastatic disease must have a HER2 test performed in a metastatic site, if tissue sample is available.
Optimal algorithm for HER2 testing
Positive for HER2 is either IHC HER2 3+ (defined as uniform intense membrane staining of > 30% of invasive tumor cells) or FISH amplified (ratio of HER2 to CEP17 of > 2.2 or average HER2 gene copy number > six signals/nucleus for those test systems without an internal control probes
Must report HER2 test result as Positive for HER2 if: a,b
Dual Probe HER2/CEP17 ratio ≥ 2.0;c,e; with an average HER2 copy number < 4 signals/cellb
Dual Probe HER2/CEP17 ratio < 2.0;c,e with an average HER2 copy number ≥ 6.0 signals/cell
Equivocal for HER2 is defined as: IHC 2+ or
FISH HER2/CEP17 ratio of 1.8-2.2 or average HER2 gene copy number 4-6 HER2 signals/nucleus for test systems without an internal control probe
Must report HER2 test result as equivocal and order reflex test (same specimen using the alternative test) or new test (new specimen, if available, using same or alternative test) if: a,b
Negative for HER2 is defined as:
Must report a HER2 test result as negative if a single test (or both tests) performed show:a,b
Indeterminate for HER2
Must report HER2 test result as indeterminate if technical issues prevent one or both tests (IHC and ISH) from being reported as positive, negative, or equivocal. Conditions may include:
Another specimen should be requested for testing to determine HER2 status. Reason for indeterminate testing should be noted in a comment in the report.
ISH rejection criteria
Test is rejected and repeated if
Same and report HER2 test result as Indeterminate as per parameters described above.
Interpretation done by counting at least 20 cells; a pathologist must confirm that counting involved invasive tumor criteria followed
The pathologist should scan the entire ISH slide prior to counting at least 20 cells or use IHC to define the areas of potential HER2 amplification.
If there is a second population of cells with increased HER2 signals/cell and this cell population consists of more than 10% of tumor cells on the slide (defined by image analysis or visual estimation of the ISH or IHC slide), a separate counting of at least 20 nonoverlapping cells must also be performed within this cell population and reported.
For brightfield ISH, counting requires comparison between patterns in normal breast and tumor cells because artifactual patterns may be seen that are difficult to interpret. If tumor cell pattern is neither normal nor clearly amplified, test should be submitted for expert opinion.
Acceptable [IHC and] ISH testsg
Should preferentially use an FDA-approved IHC, brightfield ISH, or FISH assay.g,h
IHC rejection criteria
Test is rejected and repeated or tested by FISH if:
IHC interpretation criteria
Positive HER2 result requires homogeneous, dark circumferential (chicken wire) pattern in > 30% of invasive tumor
Interpreters have method to maintain consistency and competency
Should interpret IHC test using a threshold of more than 10% of tumor cells that must show homogeneous, dark circumferential (chicken wire) pattern to call result 3+, HER2 positive.
Reporting requirements for all assay types
Report must include guideline-detailed elements
Same except for changes to reporting requirement and algorithms defined in this table. (Data Supplements 9 and 10)
Optimal tissue handling requirements
Time from tissue acquisition to fixation should be as short as possible; samples for HER2 testing are fixed in 10% neutral buffered formalin for 6–48 hours; cytology specimens must be fixed in formalin.
Samples should be sliced at 5-mm to 10-mm intervals after appropriate gross inspection and margins designation and placed in sufficient volume of neutral buffered formalin
Duration of fixation has been changed from 6-48 hours to 6-72 hours. Any exceptions to this process must be included in report.
Optimal tissue sectioning requirements
Sections should ideally not be used for HER2 testing if cut > 6 weeks earlier; this may vary with primary fixation or storage conditions
Optimal internal validation procedure
Validation of test must be done before test is offered
Data Supplement12 lists examples of various external quality assurance schemes.
Optimal initial test validation
Initial test validation requires 25-100 samples tested by alternative validated method in the same laboratory or by validated method in another laboratory
Laboratories performing these tests should be following all accreditation requirements, one of which is initial testing validation. The laboratory should ensure that initial validation conforms to the published 2010 ASCO/CAP Recommendations for IHC Testing of ER and PgR guideline validation requirements with 20 negative and 20 positive for FDA-approved assays and 40 negative and 40 positive for LDTs. This requirement does not apply to assays that were previously validated in conformance with the 2007 ASCO/CAP HER2 testing guideline, and who are routinely participating in external proficiency testing for HER2 tests, such as the program offered by the CAP (Data Supplement 12).
Proof of initial testing validation in which positive and negative HER2 categories are 90% concordant with alternative validated method or same validated method for HER2
Laboratories are responsible for ensuring the reliability and accuracy of their testing results, by compliance with accreditation and proficiency testing requirements for HER2 testing assays. Specific concordance requirements are not required. (Data Supplement 11)
Optimal monitoring of test concordance between methods
Concordance testing must be done prior to initiation of testing, optimally as the form of testing validation. If concordance is below 95% for any testing category, that category of test result of either FISH or IHC must be automatically flexed to alternative method before final interpretation.
See text below under “Optimal Laboratory Accreditation”
Optimal internal QA procedures
Should review and document external and internal controls with each test and each batch of tests.
Ongoing quality control and equipment maintenance
Initial and ongoing laboratory personnel training and competency assessment
Use of standardized operating procedures including routine use of control materials
Revalidation of procedure if changed
Ongoing competency assessment and education of pathologists
Should perform ongoing competency assessment and document the actions taken as a part of the laboratory record.
Optimal external proficiency assessment
Participation in and successful completion of external proficiency testing program with at least two testing events (mailings) a year
Satisfactory performance requires at least 90% correct responses on graded challenges for either test
Optimal laboratory accreditation
Onsite inspection every other year with annual requirement for self-inspection
Same (Data Supplement 11).
ASCO Guideline Disclaimer: The clinical practice guidelines and other guidance published herein are provided by the American Society of Clinical Oncology, Inc. ("ASCO") to assist practitioners in clinical decision making. The information therein should not be relied upon as being complete or accurate, nor should it be considered as inclusive of all proper treatments or methods of care or as a statement of the standard of care. With the rapid development of scientific knowledge, new evidence may emerge between the time information is developed and when it is published or read. The information is not continually updated and may not reflect the most recent evidence. The information addresses only the topics specifically identified therein and is not applicable to other interventions, diseases, or stages of diseases. This information does not mandate any particular course of medical care. Further, the information is not intended to substitute for the independent professional judgment of the treating physician, as the information does not account for individual variation among patients. Recommendations reflect high, moderate or low confidence that the recommendation reflects the net effect of a given course of action. The use of words like "must," "must not," "should," and "should not" indicate that a course of action is recommended or not recommended for either most or many patients, but there is latitude for the treating physician to select other courses of action in individual cases. In all cases, the selected course of action should be considered by the treating physician in the context of treating the individual patient. Use of the information is voluntary. ASCO provides this information on an "as is" basis, and makes no warranty, express or implied, regarding the information. ASCO specifically disclaims any warranties of merchantability or fitness for a particular use or purpose. ASCO assumes no responsibility for any injury or damage to persons or property arising out of or related to any use of this information or for any errors or omissions.