Established guidance for oestrogen receptor, progesterone receptor and HER2 testing on breast cancer specimens is prompt fixation in 10% neutral buffered formalin for roughly 6 to 72 hours, with the cold ischaemia time recorded. Under-fixation and over-fixation can both cause false-negative or unreliable staining.
If a result does not fit the morphology, check fixation and ischaemia time before repeating or reporting, and record both on the requisition.
- Fix breast specimens promptly in 10% neutral buffered formalin.
- Aim for 6 to 72 hours of fixation.
- Record cold ischaemia and fixation times.
- Question unexpected negative results against fixation history.
Why it matters
Pre-analytical errors are a common and avoidable cause of discordant biomarker results.
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