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RESEARCH PRODUCT

Prevalence and Clinical Outcomes for Patients With ALK Gene Rearrangement in Europe: Preliminary Results from the European Thoracic Oncology Platform Lungscape Project

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ABSTRACT Background The prevalence of ALK gene rearrangement (ALK+) in European patients with non-small cell lung cancer (NSCLC) is unknown. The Lungscape project provides a platform to evaluate its expression and clinical significance in a large cohort of patients with resected NSCLC from 13 European sites in 11 countries. Methods Participating sites retrospectively identified cases of NSCLC with clinical demographic and outcome data, and available tissue for research according to predefined protocol criteria. Local ethical and regulatory approvals were adhered to. Clinical data were entered to a central, secure database. Accepted cases on the basis of completeness of clinical data were assessed for ALK expression using immunohistochemistry (IHC) using antibody clone 5A4 (Novocastra) and an H-score modified after Ruschoff et al. All cases were analysed at participating clinical pathology laboratories using the same protocol, control tissue microarray and after passing an external quality assurance exercise. Results To date 998 cases of adenocarcinoma have been accepted to the database and ALK IHC results are available for 743 (74%). Positive IHC staining is present in 54 cases (7.3%) with IHC 3+ in 17 cases (2.3%), 2+ in 6 cases and 1+ in 31 cases. The median H-score is 45 (range 1-300) with homogeneous staining in 30% of cases and heterogeneous staining in at least 70% of cases. In total there are 38% women and 62% men, the proportion of stage I, II and III is 55, 23 and 22 % respectively, 16% of cases are never smokers and 99% Caucasian ethnicity. The median age of all cases (n = 998) is 65 years (range 23 - 86) and for IHC + 63.2 years. With respect to gender and smoking status 11% of women, 5.6% of men, 13% of never-smokers, 5.3% of former smokers and 9.3% of current smokers demonstrated positive IHC for ALK. Conclusions The preliminary results for this large multicentre European cohort demonstrate a prevalence of ALK assessed by IHC of 7.3%, with IHC 3+ expression in 2.3% of cases. Correlation of IHC scores with fluorescent in situ hybridisation, clinical demographics and outcomes is ongoing and will be presented. Disclosure All authors have declared no conflicts of interest.