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M. Bouchahda



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    MO10 - Molecular Pathology II (ID 127)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track: Pathology
    • Presentations: 1
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      MO10.03 - Decreased KRAS and Increased HER2 or PI3K mutations prevalence in the French emigrant population from African continent in lung adenocarcinoma metastatic cancer (ID 3106)

      16:15 - 17:45  |  Author(s): M. Bouchahda

      • Abstract
      • Presentation
      • Slides

      Background
      Approximately 1.2 million people are diagnosed with lung cancer every year. The identification of genomic alteration can impact therapeutics. EGFR mutation status predicts how patients can respond to EGFR tyrosine kinase drugs (EGFR-TKI). EGFR positive patients have an improved response rate to erlotinib or gefitinib; KRAS mutated tumors are not sensitive to EGFR-TKI. Recently, it has been published that patients with mutations inHER2 have a high response rate to trastuzumab. The prevalence of EGFR and KRAS mutations are well known to be associated with sex, histological type of tumor, smoking status and also ethnic origin. HER2, BRAF and PI3K are relevant gene candidates to emerging therapies. Mutation prevalence of the latter genes has not yet been investigated in large populations.

      Methods
      We have analyzed 1375 consecutive patients with metastatic lung adenocarcinomas having the screening of EGFR, KRAS, BRAF, PI3K and HER2 gene mutational status in the Paul Brousse platform between November 2011 and April 2013. The DNA mutation screening was performed using the HRM technology and their identification were analyzed by allelic discrimination and/or sequencing. Our database included all mutations results as well as anonymous diagnosis and socio-demographic data. The birth location has been self-reported.

      Results
      Of the 1375 tumors, the frequencies of EGFR, KRAS, BRAF or HER2 mutations were those usually reported in Caucasian population. Mean age was 65.2 years (SD = 11.2), 821 were male and 519 female. Among our population, 140 patients reported of African birth location, 1220 of European birth location and 15 of Asian birth location.

      TABLE 1. Mutation prévalance and birth location
      European birth location African birth location Asia birth location Total
      EGFR (n/%) 129 (10.6) 13 (9.3) 5 (33.3) 147/1375 (10.7)
      KRAS (n/%) 318 (26.3) 21 (15.0) * 340/1366 (24.9)
      BRAF (n/%) 23 (1,9) 1 (0,75) * 24/1345 (1.8)
      HER2 (n/%) 13 (1.1) 4 (2.9) * 19/1327 (1.7)
      PIK3CA (n/%) 20 (2.0) 5 (4,2) * 25/1159 (2.2)
      *Low effective
      The percentage of EGFR mutations was higher in Asiatic patients, as previously reported. Interestingly the KRAS mutation rate was significantly lower in the African patients (15.0%, CI: 10.0 – 21.9) than in the European patients (26.3%; I: 23.9 – 28.8; p = 0.004). HER2 and PI3K mutation prevalences were more than doubled in African population compared to European population (Fisher's Exact Test, respectively p = 0.10; p = 0.17).

      Conclusion
      Our data show different EGFR, KRAS, and HER2 mutation rates according to the geographical birth location of patients. Interestingly, we noted a significant decreased Kras and higher HER2 and PI3K mutations prevalence in African birth location mutation rates compared to the other populations studied. The incidence of these mutations had not been extensively studied in the population of African birth location. That could suggest, especially in this population, the importance of systematic HER2 and PI3K screening to investigate specific targeted therapy.

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