The HER2 clinical practice guidelines from CAP/ASCO apply to all IHC and FISH methodologies.
- Rapid immersion of specimens in fixative is critical, and must occur within one hour of the biopsy or resection.
- Excisional specimens should be fixed in 10% neutral buffered formalin (NBF) for 6 – 72 hours at room temperature.
- For cases with negative HER2 results by IHC that were fixed outside these limits, confirmatory analysis by ISH is strongly recommended.
- If HER2 FISH results are negative, and the fixation time is known to be longer or shorter, this should be noted.
- If alternative fixative is used, the fixative must be validated against results for the same specimens fixed in 10% NBF.
- The tissue handling requirements must be standardized and reported on every specimen.
- If an alternative fixative is used, the laboratory's director is responsible for test performance.