ALK
(2p23) Gene Rearrangement
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 newly diagnosed non-small cell, non-squamous lung
carcinomas or such metastatic lung carcinomas that have not had a primary resection
available for testing. ALK (2p23) gene rearrangements can be found in 2-7% of
non-small cell lung carcinomas (NSCLC), more commonly in adenocarcinomas
of never or light smokers, whose tumors lack EGFR and KRAS
mutations. ALK gene rearrangements,
due to fusion with various other genes (such as ALK-EML4) render the
tumors sensitive to ALK inhibitors; such as crizotinib (while resistant to EGFR
tyrosine kinase inhibitor therapies)
https://www.nccn.org/professionals/physician_gls/pdf/nscl.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:
Fluorescent in-situ hybridization (FISH)
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.
Reference
Range:
ALK gene
rearrangement present = positive result
ALK gene
rearrangement not detected = negative result
CPT codes:
88377
Test
reported:
Results are reported within 7-10 days
