Table 2 Recommended specimens for molecular biomarker testing in colorectal cancer (CRC)
From: A practical guide to biomarkers for the evaluation of colorectal cancer
Sample type | Recommended: formalin fixed paraffin embedded (FFPE) tissue [71] Alternatives: cytology specimen (requires additional validation); Liquid biopsy (serum or plasma) possibly in near future |
Sample source | Recommended: metastatic or recurrent tumor tissue preferred for targeted therapy [71] Alternative: primary tumor tissue acceptable *Both primary and metastatic CRC OK for Lynch syndrome screening [70] |
Minimum tissue needed | In general, assays require a minimum of 10–20% tumor content (assuming LOD = 5%); Ideally, 100–500 ng DNA (ten 5-µm sections with 10 mm × 10 mm area of tumor); As little as 10 ng DNA can work (about 2 × 5 mm needle core) [77] |
Tumor enrichment | Tumor cores from FFPE block or tumor microdissection from cut sections (tumor marking by Pathologist—avoid necrosis/lymphoid tissue/adenoma /mucin/fat) |
Turn-around time | 90% of specimens sent out for testing within three working days; 90% of reports be available within 10 working days from the date of receipt in the molecular laboratory [71] |
