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Table. 3.

Table. 3.

Recommendations for pre-analytical phase of plasma EGFR variant testing

Steps Recommendations
1. Collection of whole blood sample 1.1. Plasma is more suitable than serum for cfDNA analysis.
1.2. Tubes with or without cell stabilizer can be used. For tubes without cell stabilizer, an EDTA tube is recommended. If processing of whole blood is impossible within 4–6 hr after blood collection, tubes with cell stabilizer should be considered for use.
1.3. Blood volume should be sufficient to obtain the plasma volume that is recommended in the manufacturers’ instructions.
2. Transport of whole blood sample to laboratory 2.1. Hemolysis and agitation of whole blood should be avoided.
2.2. Whole blood samples should be transported within the proper time duration after blood collection according to the storage requirements of whole blood.
3. Storage requirements for whole blood 3.1. Whole blood in EDTA tubes should be processed within 4–6 hr at room temperature or 4°C.
3.2. For tubes with cell stabilizer, whole blood should be stored according to manufacturers’ instructions.
4. Plasma separation from whole blood 4.1. For plasma isolation, double centrifugation is recommended.
4.2. Buffy-coat contamination should be avoided.
5. Storage requirements of plasma 5.1. cfDNA should be extracted immediately after separating plasma.
5.2. For short-term storage, plasma can be stored for 3 hr at 4°C.
5.3. For long-term storage, plasma should be stored at −20°C or −80°C.
6. Extraction of cfDNA 6.1. Individual laboratories should choose the cfDNA extraction method considering performance, time, and cost.
7. Quality control of cfDNA 7.1. The quantity and quality of extracted cfDNA should be checked before downstream analysis.
8. Storage requirements for cfDNA 8.1. Downstream analysis should be performed immediately.
8.2. cfDNA should be archived below −20°C.
8.3. Multiple aliquoting is recommended to avoid multiple freeze–thaw cycles.

Abbreviations: EGFR, epidermal growth factor receptor; cfDNA, cell-free DNA.

Ann Lab Med 2022;42:141~149

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