Alternative molecular tests such as fluorescence in situ hybridization (FISH) and reverse transcription polymerase chain reaction (RT-PCR) are more limited in performance and the range of fusions identifiable, and a Pan-TRK immunohistochemistry antibody is increasingly used as an efficient (cheaper) screen for aberrant TRK protein expression, which would suggest a fusion is present, but has shown poor sensitivity and specificity that varies by cancer type relative to NGS and is not recommended as a sufficient diagnostic method1,10. The gene discussed is NTRK1; the disease is cancer.