Xiuning Le, Mary Linton Peters, Paul A VanderLaan, Daniel B Costa and Deepa Rangachari
Fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) represent the current standard for identification of therapeutically relevant anaplastic lymphoma kinase (ALK) rearrangements in advanced non-small-cell lung cancers (NSCLCs). Use of tyrosine kinase inhibitors (TKIs) targeting the oncogenic ALK fusion protein is approved for use in advanced ALK-rearranged NSCLCs and with benefits both with regards to clinical outcomes and quality of life when compared with traditional palliative cytotoxic therapies. We report here 2 cases in which initial standard of care ALK testing by FISH yielded false positive results, leading to delays in determination of optimal systemic therapy.