Colorectal
Carcinoma Molecular Analysis
Clinical Significance:
Recently
established guidelines from the American Society for Clinical Pathology (ASCP),
College of American Pathologists (CAP), Association for Molecular Pathology
(AMP) and/or the American Society of Clinical Oncology (ASCP) recommend testing
for all resected colorectal carcinomas or metastatic colorectal
carcinomas and selected biopsy cases where resection will not be performed or
available. Colorectal
carcinoma molecular analysis is a panel of the following molecular tests for
the following:
- KRAS Mutation
(codons 12, 13, 61, 117, and 146)
- NRAS Mutation (codons
12, 13, 61, 117, and 146)
- BRAF V600 Mutation
Assay
- Microsatellite Instability (MSI), reflex to mismatch
repair (MMR) deficiency (MLH1, MSH2, MSH6, PMS2) by Immunohistochemistry
if MSI-H.
- HER2 gene
amplification by FISH
- NTRK
gene rearrangement by immunohistochemistry (IHC) with reflex of positive cases to confirmatory RNA-based NGS
analysis.
https://www.nccn.org/professionals/physician_gls/pdf/colon.pdf
Specimen
Requirements and Collection:
Formalin-fixed tissue containing a sufficient amount of tumor (generally
at least several mm of tumor tissue submitted in the tissue block)
Methodology:
DNA isolation and extraction, library prep, fluorescent
in-situ hybridization (FISH), immunohistochemistry (IHC), and next-generation
sequencing (NGS)
Forms:
Molecular pathology requisition form
Transport:
Send formalin-fixed, paraffin-embedded (FFPE) tissue and cell block
containing tumor at room temperature.
Also acceptable 10-unstained, 4-5 micron slides with 1 post
H&E. Please include a surgical
pathology report
Unacceptable
specimen:
Specimens fixed in alternative fixatives or metal fixatives (ex. B-plus). Decalcified specimens.
CPT codes:
88381, 81210, 81275, 81276x3, 81301, 81311, 81403x2, 88342, 88341x2, 88377, G0452
Test
reported:
Results are reported within 7-10 days
