Overview
EN ISO 20166-3:2019 (ISO 20166-3:2018) specifies requirements and guidance for the pre-examination (pre-analytical) processes for formalin-fixed, paraffin-embedded (FFPE) tissue when the intended analyte is isolated DNA. Published by CEN/ISO, the document standardizes handling, documentation, storage and processing steps that influence DNA integrity prior to any molecular in vitro diagnostic (IVD) assay or molecular pathology test.
Key topics and technical requirements
The standard covers practical, quality-focused elements of FFPE specimen management that impact downstream molecular testing:
- Specimen collection and processing: guidance on information to record about the specimen donor, specimen identification and processing metadata.
- Transport requirements: recommended handling and conditions for safe transport of FFPE material to preserve DNA quality.
- Formalin fixation and post-fixation: considerations that affect DNA fragmentation and chemical modification.
- Pathology evaluation and sample selection: documentation and selection of representative tissue areas for DNA extraction.
- Decalcification and embedding: potential impacts of tissue processing steps on DNA integrity.
- Isolation of DNA: general principles for DNA extraction from FFPE, including use of commercial kits or laboratory-developed protocols.
- Quality and quantity assessment: recommended assessment of isolated DNA before molecular assays to ensure suitability.
- Storage requirements: best practices for storage of FFPE blocks and isolated DNA to minimize degradation.
- Annex on storage temperature: informative material on how storage temperature affects DNA integrity in FFPE blocks.
The standard uses normative language (e.g., "shall" for requirements, "should" for recommendations) and references ISO 15189 and ISO 15190 where applicable.
Applications and users
EN ISO 20166-3 is essential for organizations involved in molecular diagnostics and tissue-based genomics:
- Medical laboratories and molecular pathology labs performing IVD assays or laboratory-developed tests.
- In vitro diagnostic developers and manufacturers validating assays that use FFPE-derived DNA.
- Biobanks and research institutions that collect, store, and distribute FFPE specimens.
- Clinical researchers and commercial organizations conducting translational studies on archival tissue.
- Regulatory authorities and quality managers establishing conformity and audit criteria.
Adopting these pre-examination standards improves reproducibility, reduces artefacts from fixation/processing, and increases confidence in genomic and mutation analyses from FFPE-derived DNA.
Related standards
- ISO 15189:2012 - Medical laboratories - Requirements for quality and competence
- ISO 15190 - Medical laboratories - Requirements for safety
- Other parts of the ISO 20166 series covering pre-analytical processes for different analytes
Keywords: FFPE tissue, pre-examination, pre-analytical, isolated DNA, molecular diagnostics, molecular pathology, DNA integrity, specimen handling, sample transport, DNA quality assessment.
