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The ImplementatioN of perSonalized medicine In NSCLC in Central Europe: EGFR testing, Histopathology, and clinical feaTures (INSIGHT) observational study assessed both implementation of epidermal growth factor receptor (EGFR) mutation testing and treatment of patients with advanced EGFR mutation-positive non-small-cell lung cancer (NSCLC) in a real-world setting in Central Europe. A total of 1785 patients from 14 cancer centers of six Central European countries were enrolled. EGFR mutations were detected in tumors of 13.8% of the patients. More than 70% of patients with advanced EGFR mutation-positive NSCLC received EGFR tyrosine kinase inhibitors as first-line therapy. The INSIGHT study demonstrated the establishment of EGFR mutation testing, a mutation rate consistent with other Caucasian patients populations, and adherence to current guidelines regarding treatment of patients with EGFR mutation-positive tumors in Central Europe.

Background and Objective: Chemotherapy for advanced non-small-cell lung cancer (NSCLC) remains marginally effective, with a 5-year overall survival rate of approximately 5%. Recently, the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor gefitinib was approved in Slovakia for the treatment of metastatic NSCLC. Gefitinib is a selective EGFR inhibitor that binds to the adenosine triphosphate binding pocket of the kinase domain and blocks downstream signaling pathways. Mutations of the EGFR gene, particularly an in-frame 15 bp deletion (delE746_A750) in exon 19 and the L858R mutation in exon 21, correlate with enhanced clinical responsiveness to EGFR tyrosine kinase inhibitors. However, the detection of these mutations and thereby prediction of the therapy outcome is sometimes unreliable due to the low sensitivity of direct sequencing if the proportion of tumor cells in the tissue is less than 25%. Therefore we decided to test the applicability of other methods, particularly high-resolution melting analysis (HRMA), for detection of these mutations in clinical samples. Methods: We analyzed 53 archival cytologic specimens for the presence of EGFR mutations, using the HRMA method. Results were verified by direct sequencing. For samples containing less than 25% tumor cells, we used mutant-enriched PCR before sequencing. We also performed a titration assay to establish the lower limit of the proportion of tumor cells for detection of EGFR mutations. Results: EGFR mutations were detected in 13 cases (24%). In-frame deletions in exon 19 were detected in eight cases (15%) and the L858R mutation in exon 21 was detected in five cases (9%). The positive results of the HRMA were confirmed by direct sequencing only in five of 13 cases. In the remaining eight positive samples, HRMA results were confirmed by sequencing analysis after mutant-DNA enrichment. The titration assay established that the lower limit for detection of EGFR mutations by HMRA was 1% tumor cells in the clinical sample. Conclusion: Our results indicated that HRMA in combination with mutant-enriched PCR represents a sensitive method for detection of EGFR mutations from cytologic specimens. When properly executed, this protocol allows identification of EGFR mutations in specimens containing a minimal percentage of tumor cells.

Mutation analysis of the epidermal growth factor receptor (EGFR) gene is an essential part of the diagnostic algorithm in patients with metastatic or recurrent non-small cell lung cancer (NSCLC). Small biopsies or cytology specimens represent80% of the available diagnostic material. EGFR mutation analyses were realized on 835 samples (675 cytology specimens, 151 formalin-fixed paraffin-embedded blocks, 5 tumors, and 4 pleural effusions). EGFR mutation analysis was performed by high-resolution melting analysis in combination with mutant-enriched polymerase chain reaction and sequencing analysis. Because of increased risk of inaccuracy in histology diagnosis of small specimens, all subtypes of NSCLC were analyzed. EGFR mutations were detected in 83 cases (10%). EGFR mutation testing failed in 5% (42/835) and was associated with poor cellularity, low percentage of tumor cells, and bad quality of DNA. Although 281 samples were evaluated as insufficient material (poor cellularity and/or unrepresentative tumor content), mutation rates were 7%. Although only adenocarcinomas or NSCLC-not otherwise specified are recommended for EGFR mutation testing, EGFR mutations in 11% of the large cell carcinomas and 4% of the squamous cell carcinomas were observed. Our results indicate that defined algorithm for EGFR testing of small diagnostic samples is sensitive, fast, and suitable even for samples with poor cellularity. The results of this testing should be evaluated depending on tumor content and DNA quality for each sample individually. At the conclusion of our results, we recommend to realize EGFR mutation analysis of small diagnostic samples regardless of the histologic subtypes of NSCLC.