Method of biopsy and sample quality for genetic mutation testing in advanced non-small cell lung cancer in a community hospital.

Abstract

271 Background: Mutated EGFR gene testing transformed the care of NSCLC. ASCO now recommends EGFR mutation testing for NSCLC (April 2011); however, no studies to assess quality of biopsy samples and adequacy for mutation testing have been done outside a trial setting. Methods: A retrospective chart review to identify patients diagnosed with NSCLC at a community hospital during 2010. A pathologist reviewed the quality of archivedbiopsy samples for histological diagnosis and adequacy for EGFR mutation testing based on ASCO criteria. Results: In 2010, 64 cases of NSCLC were diagnosed and 18 patients had definitive surgery, 46 did not. Histological 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%). Staging: stage I, II, III, IV - 18 (28%), 2 (3%), 13 (20%), 23 (36%). Biopsy material: transbronchial needle biopsy in 23 (36%), CT-guided biopsy in 13 (20%), surgery in 18 (28%), other - 10 (15%). Specimen review: 3 samples (5%) were designated as large cell carcinoma without squamous or adeno specification. 46/64 (72%) were adequate for mutation analysis; 18 (28%) were not. Among adenoca., 19/28 (68%) were adequate samples, but 9 (32%) were not. Among the 46 patients who had advanced or metastatic disease, 28 (60%) had sufficient samples, 18 (40%) did not. Among advanced adenoca. patients, the proportion without adequate sample was 9/18 (50%). Route of biopsy: 4/23 transbronchial biopsies (17%), 8/13 CT-guided biopsies (62%) and 6/10 from other sites (60%) were inadequate (p = 0.01). Conclusions: Nearly one-third of all NSCLC cases, including half of advanced adenoca., yielded poor quality specimens from the first biopsy for EGFR mutation analysis. 5% of samples lacked definitive histology. CT-guided transthoracic biopsies were at least twice as likely to yield poorer quality specimens compared to transbronchial biopsies. Poor quality tumor sampling may preclude mutation testing thus denying beneficial and less toxic therapy. Quality of tumor specimens needs to be improved in the future by the development of appropriate strategies by multidisciplinary lung cancer teams.