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IASLC ATLAS OF ALK TESTING IN LUNG CANCER
with cores from FFPE material and digital images of FISH were provided. The data from both rounds will be available at the end of 2013. International Reproducibility Study of Ventana ALK IHC Kit To study the correlation between IHC and FISH, as well as the reproducibility of the Ventana ALK IHC with the D5F3 antibody (Ventana Medical Systems, Inc.), seven international observers studied 100 evaluable cases. When the results of ALK IHC were correlated with those of ALK FISH, the sensitivity was 90% and the specificity was 95%, with a 93% accuracy relative to FISH. For the IHC interpretation, there was agreement of the IHC interpretation among all seven readers on 95% of the cases and among six of seven readers in 97% of the cases (Hirsch 2013). The authors concluded that there was an excellent intraobserver and interobserver agreement with the Ventana IHC Kit as well as excellent correlation with ALK FISH.
Conclusion
Although testing for ALK gene rearrangement using break-apart ALK FISH probes is generally recognized as a standard diagnostic criterion for ALK TKI therapy, the screening algorithm for detection of ALK-rearranged lung cancer is still under development. Groups in all parts of the world are conducting studies to develop national or regional guidelines; most of these studies focus on the standardization of both IHC and FISH tests, as well as evaluation of the sensitivity and specificity of IHC as a screening tool. As results from these studies are published, it is likely that a global consensus on an ALK screening algorithm may evolve within the next few years.