SECTION EIGHT
Dahl-Chase Diagnostic Services
MOLECULAR PATHOLOGY TESTING
FISH FOR RET GENE REARRANGEMENTS
Clinical Significance:
Non small-cell lung carcinomas (NSCLC) account for approximately 85 % of lung cancers. Targeted therapies based on genetic alterations in the tumor are appropriate for selected cases, currently principally in non-squamous NSCLC. Identifying mutations in oncogenes associated with NSCLC, physicians can distinguish patients who are more likely to benefit from certain therapies, such as tyrosine kinase inhibitors (TKI) erlotinib and gefitinib in case of EGRF mutation or critozinib in case of ALK rearrangement. Recently, cabozantinib has been recommended for use in patients with RET fusion-positive lung adenocarcinomas.
RET fusions can be found in 1-2% of NSCLC, more commonly in adenocarcinomas of never or light smokers, whose tumors lack EGFR and KRAS mutations. Patients with RET rearrangements, characteristically due to KIF5B-RET, CCDC6-RET, NCOA4-RET, and TRIM33-RET fusion, rendering the tumors sensitive to RET inhibitors such as cabozantinib (while resistant to EGFR tyrosine kinase inhibitor therapies).
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).
Forms:
Molecular Pathology requisition form
Transport:
Send paraffin block containing tumor at room temperature
Reference Range:
RET gene rearrangement present = positive result
RET gene rearrangement not detected = negative result
CPT codes:
88377
Test reported:
Results are reported within 7-10 days
