Anaplastic lymphoma kinase translocation is correlated with anaplastic lymphoma kinase expression and mutually exclusive with epidermal growth factor receptor mutation in Taiwanese non-small cell lung cancer

The echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK) fusion gene is an important biomarker for target therapy. The aim of this study is to better understand the clinical and molecular features of the EML4-ALK fusion gene in lung cancer patients in Taiwan and therefore to generate an efficient algorithm for the detection of ALK translocation. In the first cohort, ALK translocation was identified in 1 adenocarcinoma from 100 lung cancer patients by using break apart fluorescent in situ hybridization (FISH). Next, we detected 6 ALK translocations in another 40 EGFR wild type adenocarcinomas but not in 40 cases with EGFR mutation. Histological analysis revealed that solid growth with signet-ring cells or cribriform glands with extracellular mucin were noted in all the 7 ALK translocated cases. One ALK positive cancer with mucinous cribriform pattern had no ALK expression. ALK expression was correlated with ALK translocation (p < 0.001), but not with ALK gene copy number gain (CNG) (P = 0.838). ALK translocation was also mutually exclusive with EGFR mutation in Taiwanese non-small cell lung cancer (P = 0.033). These results indicate that screening tests for EGFR mutation status and/or ALK expression could help efficiently select ALK translocated patients for target therapy.