Adequacy of biopsy samples for molecular testing in patients with non-small cell lung cancer.

Abstract

e21133 Background: Testing for a mutated EGFR gene has transformed the care of NSCLC. Although ASCO recommends EGFR mutation testing for cases of NSCLC, there have been no studies to assess adequacy of biopsy samples for molecular testing in non-trial settings. Methods: A retrospective chart review to identify patients diagnosed with NSCLC at our community hospital during 2010. A pathologist then reviewed the adequacy of archivedbiopsy material for EGFR mutation testing based on ASCO criteria (Eberhard, JCO 2008). Results: In 2010, 64 cases of NSCLC were diagnosed. Demographics:Thirty-six (56%) of the patients were male; median age was 69.5 years, 27 were current smokers, 33 were ex-smokers, median survival was 4.9 months. Histologic subtypes: squamous - 28 (44%), adenocarcinoma - 23 (36%), bronchoalveolar - 3 (5%), adeno with mixed bronchoalveolar - 2 (3%), large cell - 3 (5%), and large cell neuroendocrine - 2 (3%). Twenty-eight (44%) were considered adenocarcinoma. Staging: Stage I, II, III, IV - 18 (28%), 2 (3%), 13 (20%), 23 (36%). Eight (13%) had incomplete staging information. Biopsy material: transbronchial FNA in 23 (36%), CT-guided FNA in 13 (20%), definitive surgery in 18 (28%), other - 10 patients (15%). Imaging review: 29 central lesions (45%) and 35 (55%) peripheral. Specimen review: 45/64 (70%) were adequate for EGFR mutation analysis; Twenty cases (30%) were not. Among adenocarcinoma, 19/28 (68%) cases had adequate samples, but 9 (32%) did not. Conclusions: In this series, nearly one-third of all NSCLC cases, including adenocarcinoma, did not yield sufficient specimen from the first biopsy for EGFR mutation analysis. Newer molecular markers (EGFR, EML4-ALK) with targeted therapy such as erlotinib and crizotinib are available in NSCLC so adequate tissue sampling is imperative. Lack of satisfactory tumor tissue sampling may preclude mutation testing thereby denying these patients treatment with potential benefit and lower toxicity. This has implications for planned diagnostic investigations since an appropriate site must be biopsied so as to obtain an ample sample. Efforts to improve clinician awareness about adequate tumor sampling are needed and should be a top priority for multidisciplinary lung cancer teams.