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F.S.R. Roitberg



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    P3.22 - Poster Session 3 - Epidemiology, Etiology (ID 168)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Prevention & Epidemiology
    • Presentations: 1
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      P3.22-003 - EGFR genotyping and epidemiology, clinical and pathological features in 191 patients with metastatic pulmonary adenocarcinoma in Sao Paulo - Brazil. (ID 1026)

      09:30 - 09:30  |  Author(s): F.S.R. Roitberg

      • Abstract

      Background
      EGFR activating mutations in pulmonary adenocarcinoma does confer better prognosis and are also predictive of higher response rates to both chemotherapy and EGFR-tyrosine kinase inhibitors. Therefore, EGFR genotyping in these patients (pts) is a very helpful biomarker for treatment selection. Here we aimed to report the results of consecutive EGFR genotyping in our Institution in Sao Paulo - Brazil.

      Methods
      It is a prospective, observational study on all consecutively tested samples from pts diagnosed with pulmonary adenocarcinoma and treated at ICESP. All samples were formalin-fixed and paraffin-embedded. Tumor areas were selected and macrodissected, followed by whole DNA extraction and amplification by PCR. EGFR genotyping was performed through DNA sequencing (exons 18, 19, 20 and 21) by Sanger´s methodology.

      Results
      191 pts had tumor samples genotyped between Aug/2011 and Apr/2013. Median age was 64 y (17-90), 106 (56%) female. According to ethnicity, 154 pts were Caucasian (81%), 26 African-American (14%) and 11 Asian (6%). Seventy pts were classified as never-smokers (37%), 23 (12%) as light-smokers (≤ 10 p.y.) and 95 as current smokers (51%). EGFR activating mutations could be identified in 54 out of 191 samples (28%): 35 were exon 19 deletions (65%), 15 were L858R mutation in exon 21 (30%), and three were rare mutations (G719S and G719A in exon 18, and V774M in exon 20). These mutations were found to be more frequent in females than in males (56% vs. 45%, p=0.035), and in never-smokers and light-smokers than in current smokers (77% vs. 20%, p<0.0001). It is noteworthy to mention that 11 mutations were detected in current smokers. All tumors harboring EGFR activating mutations presented TTF-1 expression by immunohistochemistry, and among those seven TTF-1-negative adenocarcinomas, no mutation was detected (p=0.0969). In a mean follow-up of 12 months, 77 pts were dead. Median overall survival was not reached in those pts whose tumors harboring EGFR-activating mutations, versus 19 months in pts with wild-type EGFR tumors (HR 0.40; 95%CI 0.29-0.78, p=0.003).

      Conclusion
      In this group of pts, the frequency of EGFR activating mutations was 28%, being more frequent in females, and never-smokers or light smokers, as previously described. Indeed, the presence of EGFR activating mutations was a favorable prognostic factor. The data here presented does reinforce the importance of testing EGFR activating mutations in all pts with TTF-1-positive, pulmonary adenocarcinoma.