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MO26 - Anatomical Pathology II (ID 129)
- Event: WCLC 2013
- Type: Mini Oral Abstract Session
- Track: Pathology
- Presentations: 1
- Moderators:E. Brambilla, V.L. Capelozzi
- Coordinates: 10/30/2013, 10:30 - 12:00, Bayside 105, Level 1
MO26.07 - Usefulness of cytological samples for the assessment of ALK rearrangements in NSCLC patients. (ID 2351)
10:30 - 12:00 | Author(s): T. Labiano
ALK gene rearrangement defines a new molecular subtype of NSCLC with response to Crizotinib, (Xalkori®) a dual MET and ALK inhibitor. To date, determination of ALK gene rearrangements has been performed in biopsies and/or surgical specimens. However, advanced lung cancer is often diagnosed by FNA cytology obtained through minimally invasive procedures, and frequently cytological specimens are the only samples available. We assessed the feasibility of determining ALK gene rearrangements in cytological samples.
We studied prospectively 53 cytological samples from 53 NSCLC patients (30 M/23 F) for ALK gene rearrangements by FISH (Abbot dual colour break apart probe). Tumour samples were obtained by bronchoscopy -FNA in 26 cases (49.1%), EBUS-FNA in 7 (13.2%), EUS-FNA in 3 cases (5.7%), CT-FNA in 3 (5.7%), and direct FNA in 6 cases (11.3%). Two cavity fluids (3.8%), 4 imprints from surgical specimens (7.5%), and 2 cellblocks received for consultation (3.8%) were also studied. FISH was performed on Papanicolau stained smears in 15 cases (28.3%), non-stained ThinPrep in 28 cases (52.8%), cell block in 9 cases (17%), and 1 stained ThinPrep. All cases were tested for EGFR and KRAS mutations.
Thirty-seven samples (69.8%) were adequate for FISH analysis. Three cases (8.1%) had ALK gene rearrangements: positive cases were non-smoker women with adenocarcinoma, two of them with signet ring cells. One case had a concurrent EGFR mutation in exon 21. FISH study was unsuccessful in 16 cases (30.2%): 10 from Papanicolau stained smears (62.5%), 5 from unstained ThinPrep (31.3%), and 1 from a cell block. Nineteen ThinPrep slides were adequate for FISH analysis (86.4%) as well as 8 out of 9 cell blocks. Correlation cytological / paraffin embedded samples was performed in 4 cases with a concordance rate of 100%.
Determination of ALK gene rearrangements in cytological specimens is feasible. It is mandatory an exquisite management and care of the samples to preserve quality. ThinPrep and cell blocks are the most suitable samples for FISH analysis, while Papanicolau stained smears provide poor results. Coexistence of ALK gene rearrangements and EGFR mutations was observed in one case, indicating that such alterations are not necessarily mutually exclusive.
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