Diagnosis of EML4-ALK Translocation With FISH, Immunohistochemistry, and Real-time Polymerase Chain Reaction in Patients With Non-Small Cell Lung Cancer.
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.
Experimental Oncology Laboratory.
Graciela
G
Cruz-Rico
Department of Pathology, Instituto Nacional de Cancerología (INCan).
Alejandro
A
Avilés-Salas
Clinic of Thoracic Oncology.
Manuel
M
Segura-González
Genomic Medicine Laboratory, Hospital General de México, Mexico City, Mexico.
Ana María
AM
Espinosa-García
Experimental Oncology Laboratory.
Laura Alejandra
LA
Ramírez-Tirado
Clinic of Thoracic Oncology.
Vicente
V
Morales-Oyarvide
Department of Pathology, Instituto Nacional de Cancerología (INCan).
Carlos
C
Rojas-Marín
Clinical and Translational Oncology Group, Institute of Oncology, Clínica del Country, Bogotá, Colombia.
Andrés-Felipe
AF
Cardona
Experimental Oncology Laboratory.|Clinic of Thoracic Oncology.
Oscar
O
Arrieta
D000230:Adenocarcinoma / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008175:Lung Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques; D009367:Neoplasm Staging; D015514:Oncogene Proteins, Fusion / Q000235:genetics* / Q000378:metabolism; D011237:Predictive Value of Tests; D060888:Real-Time Polymerase Chain Reaction
C522504:EML4-ALK fusion protein, human; D015514:Oncogene Proteins, Fusion