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Updated: Feb 3, 2026

Detection of Targetable Alterations in Non-small Cell Lung Cancer using Next-generation Sequencing
Published on: October 10, 2025
ALK Mutation Status in EGFR-negative Non-small-cell Lung Cancer Patients in Bulgaria
Slaveyko N Djambazov1, Toni Y Vekov1, Evgeni V Mekov2
1Faculty of Public Health, Medical University, Pleven, Bulgaria.
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 patients in Bulgaria.
Materials And Methods:
One hundred and thirty-two patients with EGFR-negative NSCLC were examined for ALK mutation analysis between January and June 2016. Data were obtained from patients' register of four major oncological hospitals in Bulgaria.
Results:
Data were available for 124 (93.9%) patients, tumor mass was insufficient 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 patients (1.5%) were with other type of NSCLC. Histology data were missing in 37 patients (28.0%). ALK mutation was confirmed in 5 patients (3.8%), 119 (90.2%) patients 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 first 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 prerequisite for targeted therapy and thus needs to be accurately assessed in NSCLC.
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