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Diagnosis of EML4-ALK Translocation With FISH, Immunohistochemistry, and Real-time Polymerase Chain Reaction in Patients With Non–Small Cell Lung Cancer

Cruz-Rico, Graciela PhD*; Avilés-Salas, Alejandro MD; Segura-González, Manuel MD; Espinosa-García, Ana María PhD§; Ramírez-Tirado, Laura Alejandra PhD*; Morales-Oyarvide, Vicente MD; Rojas-Marín, Carlos MD; Cardona, Andrés-Felipe MD, PhD; Arrieta, Oscar MD, MSc*,‡

American Journal of Clinical Oncology: December 2017 - Volume 40 - Issue 6 - p 631–638
doi: 10.1097/COC.0000000000000213
Original Articles: Thoracic

Objective: To assess anaplastic lymphoma kinase (ALK) rearrangement detection with immunohistochemistry (IHC) and real-time polymerase chain reaction (RT-qPCR) in comparison with fluorescence in situ hybridization (FISH).

Methods: Tumor tissue samples from 230 patients with advanced non–small cell lung cancer (NSCLC) were analyzed by FISH to detect ALK rearrangements. Additional IHC tests using 5A4 clone and RT-qPCR (variants 1 to 5) were performed in 63 and 48 patients, respectively.

Results: Thirteen percent of FISH tests were not evaluable. From the remaining tests (n=200), 18 (9.0%) were ALK positive (ALK +). ALK + patients were significantly younger at the time of diagnosis (below 55 y, 14.3% vs. 5.5%, P=0.035), were light smokers (tobacco index <10, 12.6% vs. 4.1%, P=0.049), and presented adenocarcinoma with a mucinous component (30.8 vs. 8.0%, P=0.007). When comparing FISH with IHC using a cutoff of 1+ or 2+, and only 2+ staining intensity, the sensitivity, specificity, negative predictive value, and positive predictive value were as follows: 83.3%, 100.0%, 93.75%, and 100.0%; and 55.6%, 100.0%, 84.9%, and 100.0%, respectively. For RT-qPCR, these results were 55.6, 100, 90.7, and 100.0%, respectively.

Conclusions: Our results suggest that RT-qPCR is an inadequate initial test for detecting ALK-positive lung cancer. IHC is highly useful as an initial screening test for ALK rearrangement detection in NSCLC. These results contribute to the medical literature on the establishment of IHC as a standard diagnostic test for ALK rearrangements in NSCLC.

Supplemental Digital Content is available in the text.

*Experimental Oncology Laboratory

Clinic of Thoracic Oncology

Department of Pathology, Instituto Nacional de Cancerología (INCan)

§Genomic Medicine Laboratory, Hospital General de México, Mexico City, Mexico

Clinical and Translational Oncology Group, Institute of Oncology, Clínica del Country, Bogotá, Colombia

All authors contributed equally.

The authors declare no conflicts of interest.

Reprints: Oscar Arrieta, MD, MSc, Thoracic Oncology Unit, Instituto Nacional de Cancerología (INCan), San Fernando #22, Sección XVI, Tlalpan, 14080 Mexico City, Mexico. E-mail: ogar@unam.mx.

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