ROS1 Rearrangement by FISH

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Pseudonyms: ROS1 (6q22), ROS1 Fusion, Lung Cancer, Non-small cell lung cancer, NSCLC, FISH
 
TURNAROUND TIME:   7 to 10 days
 
CPT CODES:   88271X2, 88274x1, 88291x1
 
TESTING METHODOLOGY:
Fluorescence in situ hybridization (FISH) Analysis
 
SPECIMEN REQUIREMENTS:

Specimens:

Paraffin-embedded, formalin-fixed tissue block or three 4 µm sections on positively-charged glass slides including one consecutive hematoxylin and eosin-stained (H and E) section with the tumor areas marked.
 
  • Stability:  Paraffin block: ambient temperature, indefinite
  • Unacceptable Conditions: Tissue not verified for the presence of tumor by a pathologist; specimens fixed in fixatives other than formalin.
A Cytogenetics Laboratory Test Requisition must accompany the specimen. Contact the Cytogenetics Laboratory at 918-502-1722 to obtain further information.
 
INTERPRETIVE DATA:
 
Test Summary: Fluorescence in situ hybridization (FISH) analysis designed to determine the presence of a rearrangement of the ROS1 receptor tyrosine kinase gene in non-small cell lung cancer cells (NSCLC). ROS1 gene rearrangements resulting from fusion of the ROS1 gene with SLC34A2, FIG1, CD74 and GOPC or with other fusion partners have been identified in a subset of patients with NSCLC with distinct clinical characteristics that are similar to those observed in patients with ALK rearrangements.  ROS1 rearrangements are more common in adenocarcinomas of younger patients who are light smokers or who have never smoked.
 
Method: A dual-color FISH analysis performed on interphase nuclei using a break-apart ROS1 gene probe (Kreatech); analysis of 50 interphase nuclei from tumor cells
 
Reference Values: An interpretive report will be provided.
 
Interpretation:
A positive result (ROS1 rearrangement) is reported when the percent of cells with an abnormality exceeds the normal cutoff for the ROS1 probe. A negative result indicates no rearrangement of the ROS1 gene.
 
Indications for Use:
Patients with non-small cell lung cancer who are being considered for treatment with crizotinib or other ROS1-targeted therapy.