P2.13 Topic: Advanced NSCLC Frequency of Uncommon EGFR Mutations in CR

Abstract

Lung cancer is one of the neoplasms with the highest mortality around the world, being adenocarcinoma the most common subtype. EGFR is a common mutation present in adenocarcinoma, mainly in young women and nonsmokers. In Asians has a significantly higher frequency of about 40% of the mutations and around 20% in the Caucasians. EGFR mutations are diverse. Approximately 85%-90% of EGFR mutations occurred in exon 19 deletion mutations and exon 21 point mutations L858R. Among Latinos, EGFR mutations were found in 23.3%. The highest frequency was observed in Latinos from PE (37%) followed by the United States (23%) and MX (18%). EGFR exon 19 deletions were the most frequent type of mutation among Latinos (47.6%) followed by EGFR L858R (38%) and exon 20 insertions (9.5%). Uncommon mutations, such as point mutations in exon 20 (S7681), substitution in the exon 18 (G719X, E790K/E790A) and complex mutations (example S768I + G719X), are present in less than 10% of all EGFR mutations. The aim of these paper is to determine the frequency of the uncommon mutations of the EGFR gen in a Latinamerican country, CR. Specimens from 269 advanced (IIIB/IV) patients were diagnosed with lung adenocarcinoma and underwent EGFR gene detection at Hospital Rafael Ángel Calderón Guardia in CR. EGFR mutation was documented in 85 cases, of which 3,5% (3 patients) presented exon 18 mutation and 17.6% (15 patients) in exon 20. The most frequent mutation observed was in 19 exon (44%) followed by 21 exon (31.7%). Mutations in 18 and 20 exons occurred with a slightly more frequency in men, unlike the mutations in exons 19 and 21. The behavior of EGFR mutations in CR is similar to that already studied in the rest of the Latin American population.