5
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 6–72 hours; cytology specimens must be fixed in
formalin.
• Samples should be sliced at 5- to 10-mm intervals after appropriate gross
inspection and margins designation and placed in sufficient volume of neutral
buffered formalin. 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 performed before test is offered
Optimal Initial Test Validation
➤ 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 Laboratory Developed Tests (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.
➤ 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.
Optimal Monitoring of Test Concordance Between Methods
➤ See next page under "Optimal Laboratory Accreditation."
