Identification of EGFR mutations in cytological specimens of non-small cell lung carcinoma from a single institute.

Epidermal growth factor receptor (EGFR) mutation testing is pivotal for the precise treatment of non-small cell lung carcinoma (NSCLC). Generally, detection of EGFR mutations in surgical specimens is the most accurate and the most reliable. However, some NSCLC patients in advanced stages are inoperable. Therefore, other specimens such as cytological samples are alternative options for EGFR mutation detection. In this study, cytological samples from 291 NSCLC patients were tested for EGFR mutations using the amplification-refractory mutation system (ARMS). The results showed that the EGFR mutation rate was 45.3%, and the most common mutation type was deletion in exon 19 (19del), followed by L858R mutation in exon 21. The results were consistent with that of the large cohort histological samples. This study demonstrates that using cell block for EGFR mutation detection has a high success rate and can yield reliable results. It also solidifies that the use of cytological samples possesses relatively high clinical practicability, so that cytological samples may substitute histological samples. In addition, an assessment of the tumor cell quantity prior to detection could improve the positive rate. Considering tumor heterogeneity, both histological and cytological samples are suggested to be collected for testing, if possible.