P221 The Use Of Cytological Specimens To Determine Epidermal Growth Factor Receptor (egfr) Mutation Status In Non-small Cell Lung Cancers (nsclc)

Abstract

Introduction Treatments for patients with advanced NSCLC are improving, including the use of drugs which act on those cancers that express EGFR mutations. However, determination of EGFR status requires an adequate sample for analysis and national guidelines indicate that this is best obtained by tissue biopsy. Unfortunately, in this ill patient group tissue biopsy may be problematic and a diagnosis is often made through cytology alone. There are few published studies on the utility of cytological specimens for EGFR analysis and we wished to study this further. Methods We reviewed all lung cancer samples that had been sent from our large cancer unit since EGFR mutation analysis became available 35 months ago, comparing the yield from cytology and formal tissue biopsy. Results Of 330 cases sent for EGFR analysis, cytology was the only sample available in 92 cases [28%] – as might be expected this group contained individuals with poor lung function and high rates of metastatic disease (Mean FEV1 0.76 L, Median stage=4). Samples were most commonly obtained from EBUS [59%], bronchial brushings/washings [23%], or pleural aspiration [11%], and 64 [70%] of these were deemed adequate for mutation analysis. Although formal histological samples were more likely to provide sufficient material for EGFR analysis than cytological methods [84% vs. 70%], those acquired through EBUS or pleural aspiration gave comparable rates [81% and 88% respectively]. Overall, 34 cases [10%] were EGFR positive, and 4 of these [12%] were based on cytology samples alone. Conclusions Our data show that most cytopathological specimens, especially when obtained by EBUS or pleural aspiration, will provide adequate material for EGFR analysis and increase the identification of patients eligible to receive targeted therapy. As cytology specimens can often be obtained through relatively non-invasive means our findings further underline the importance of attempting a tissue diagnosis even in patients who may otherwise be regarded as too unwell for more intensive investigations.