397 Folia Medica I 2018 I Vol. 60 I No. 3 DOI: 10.2478/folmed-2018-0010 ALK Mutation Status in EGFR-negative Non-small-cell Lung Cancer Patients in Bulgaria Slaveyko N. Djambazov 1 , Toni Y. Vekov 1 , Evgeni V. Mekov 3 , Georgi S. Slavchev 2 , Rosen E. Petkov 3 , Dimitar T. Kostadinov 3 , Ljubliana T. Konteva 1 1 Faculty of Public Health, Medical University, Pleven, Bulgaria 2 Health Technology Assessment Institute LTD, Sofa, Bulgaria 3 Clinical Center for Pulmonary Diseases, Medical Faculty, Medical University of Sofa, Sofa, Bulgaria Correspondence: Slaveyko N. Djambazov, Faculty of Public Health, Medical University of Pleven, 1 K. Ohridski Str., 5803 Pleven, Bulgaria E-mail: slaveykodjambazov@gmail. com Tel: +359887523765 Received: 05 Sept 2017 Accepted: 28 Dec 2017 Published Online: 15 Jan 2018 Published: 28 Sept 2018 Key words: ALK mutation, preva- lence, non-small-cell lung cancer, Bulgaria, NSCLC Citation: Djambazov SN, Vekov TY, Mekov EV, Slavchev GS, Petkov RE, Kostadinov DT, Konteva LT. ALK mutation status in EGFR-neg- ative non-small-cell lung cancer patients in Bulgaria. Folia Med (Plovdiv) 2018;60(3):397-401. doi: 10.2478/folmed-2018-0010 Background: Patients with non-small-cell lung cancer (NSCLC) with anaplastic lymphoma kinase (ALK) rearrangement mutation are found to be 3–13%. Aim: To evaluate the prevalence of ALK mutations in EGFR-negative NSCLC pa- tients in Bulgaria. Materials and methods: One hundred and thirty-two patients with EGFR-nega- tive NSCLC were examined for ALK mutation analysis between January and June 2016. Data were obtained from patients’ register of four major oncological hospi- tals in Bulgaria. Results: Data were available for 124 (93.9%) patients, tumor mass was insufcient for analysis in 8 (6.1%) patients. Most of the patients were with adenocarcinoma (82 patients, 62.1%); 11 patients (8.3%) were with squamous histology and 2 pa- tients (1.5%) were with other type of NSCLC. Histology data were missing in 37 patients (28.0%). ALK mutation was confrmed in 5 patients (3.8%), 119 (90.2%) pa- tients had ALK wild type. ALK positive patients were with adenocarcinoma (n=3), squamous cell carcinoma (n=1) and other type (n=1) NSCLC. All ALK mutations were observed in never smokers (n=3) and former smokers (n=2). Conclusion: The present study is the frst of this kind in Bulgaria – it investigates the prevalence of ALK mutation rate in EGFR-negative NSCLC patients, which was found to be 3.8%. The presence of EGFR, ALK or other driver mutations is a pre- requisite for targeted therapy and thus needs to be accurately assessed in NSCLC. BACKGROUND Lung cancer is the leading cause of death from cancer worldwide with 14.1 million people diagnosed per year and mortality of 8.2 million annual deaths. 1,2 The disease remains the most common cancer in men worldwide. Non-small-cell lung cancer (NSCLC) is the most common type of lung cancer, making up 80-85% of all cases. Chemotherapeutic regimens are gold standard for treatment of advanced NSCLC but the clinical outcomes are discouraging and the impact on median overall survival (OS) barely reaches 12 months and the five-year survival rate is 16%. 3,4 Lung cancer is the most common malignancy in men and the fifth most common in women in Bulgaria. 5 It accounts for 19.3% of all newly diag- nosed cancer cases in men and for 5.3% in women. The crude incidence rate is 95.1 per 100 000 men and 21.4 per 100 000 women. 73.2% of all cancer cases are morphologically confirmed. The most frequently diagnosed lung cancer type is squamous cell carcinoma (50.2%), followed by adenocarcinoma (21.9%), and small cell carcinoma (15.5%). 5 Cancer management has undergone significant changes over the past decade. New targets and driver oncogenes (which initiate and maintain malignancy) have been identified. The gained information for oncogenes, such as the epidermal growth factor receptor (EGFR), Kirsten rat sarcoma viral onco- gene (KRAS), v-raf murine sarcoma viral oncogene homolog B1, anaplastic lymphoma kinase (ALK), and the development of new drugs that specifically target mutations in them have led to improvements in survival without significant toxicities. 6 The prevalence of ALK rearrangement mutation ORIGINAL ARTICLES, MEDICINE