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MINI 10 - ALK and EGFR (ID 105)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
MINI10.06 - Incidence of ALK Gene Rearrangements in a Prospectively, Consecutively Collected Caucasian Population with Pulmonary Adenocarcinomas (ID 684)
16:45 - 18:15 | Author(s): J.B. Soerensen
EML4-ALK oncogene fusion in non- small cell lung cancer, identifies patients sensitive to ALK-targeted inhibitors. Estimates of the frequency of this fusion oncogene rearrangement are primarily available from selected patient cohorts. The true incidence in an unselected Caucasian population is unknown. This study assess the incidence of ALK rearrangement in a population based cohort, together with correlation to gender, age, smoking habits, as well as pathological and clinical.
All patients in a well-defined catchment area of 1.7 million people in the capital region of Denmark diagnosed with pulmonary adenocarcinomas from April 1. 2013 to July 31. 2014 were prospectively included. The type and location of the diagnostic material, and data on smoking and clinical characteristics were registered. The rearrangement analyses were investigated by up-front analysis with immunohistochemistry (IHC) using clone 5A4 Novocastra and all IHC positive tests were also subsequently tested by FISH using Zytovision, spec. ALK Dual Color Break Apart.
Among 797 patients included in this study, 777 patients (97.5%) patients had sufficient material for mutation analysis. Fourteen patients (1.8%, 95% CI 1.1-3.0) were IHC positive, all with 3+ reaction. All but one of these were also FISH positive. Eight patients (57%) were women. Median age was 62.7 years. All tumors were strongly TTF1 positive with mucin present in the cytoplasm of the malignant cells without dominance of any subtype. Ten patients (71.4) were diagnosed in stage IIIa or higher. Nine patients (64.3%) were never smokers, 3 (21.4%) were light smokers (0.5-10 yrs), 2 (14.3 %) were heavy smokers (25-40 yrs). More than 1/3 (36%) of the analyses were done on cytological, cellblock material. Seven patients had localized or locally advanced disease and did not receive crizotinib. Among seven patients with advanced disease, six received crizotinib with one complete response in a light smoker (male) and three partial responses in two never and one light smoker (response rate 67%). One out of three females receiving crizotinib achieved a response while it was three out of three males. No heavy smokers received crizotinib despite an ALK translocation was identified. Median progression free survival for patients receiving crizotinib was 3.4 months (range 0-20 months).
ALK rearrangement analysis was possible in 97.5% of all patients with pulmonary adenocarcinomas. 1.8% had a positive test. Rearrangements were primarily found in never/light smokers. No difference in gender regarding rearrangement status was observed. Response rate to crizotinib was 67% and was in this study more frequent in males than in females (not significant). Chance of response was equal in light and in never smokers.
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