title: Quantitative detection of EGFR mutations in circulating tumor DNA derived from lung adenocarcinomas.
abstract: OBJECTIVE
  Examination of somatic epidermal growth factor receptor (EGFR) mutations is now a diagnostic routine for treatment of cancer using EGFR tyrosine kinase inhibitors (EGFR-TKI). Circulating tumor DNA is a promising target for noninvasive diagnostics. We evaluated its utility by quantitatively detecting activating and resistant mutations, which were measured with BEAMing (beads, emulsion, amplification, and magnetics).
  
  
  METHODS
  Twenty-three patients with lung cancer with progressive disease after EGFR-TKI treatment and 21 patients who had never been treated with EGFR-TKIs were studied. Their primary tumors were confirmed to have activating mutations. In the plasma DNA of each patient, the activating mutation found in the corresponding primary tumor and the T790M resistance mutation were quantified by BEAMing.
  
  
  RESULTS
  In 32 of 44 patients, activating mutations were detected in the plasma DNA [72.7%; 95% confidence interval (CI), 58.0%-83.6%]. The T790M mutation was detected in 10 of 23 patients in the first group (43.5%; 95% CI, 25.6%-53.4%). The ratio of T790M to activating mutations ranged from 13.3% to 94.0%. The peak of the distribution of the mutation allele fraction in the plasma DNA was in the 0.1% to 1% range.
  
  
  CONCLUSIONS
  The major advantage of BEAMing is its ability to calculate the fraction of T790M-positive alleles from the alleles with activating mutations. This feature enables the detection of increases and decreases in the number of T790M mutations in cancer cells, regardless of normal cell DNA contamination, which may be useful for monitoring disease progression. Circulating tumor DNA could potentially be used as an alternative method for EGFR mutation detection.
authors: Research Institute, Departments of Thoracic Oncology and Thoracic Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Higashinari-ku, Osaka, Japan.
authors: Kazuya
authors: K
authors: Taniguchi
authors: Junji
authors: J
authors: Uchida
authors: Kazumi
authors: K
authors: Nishino
authors: Toru
authors: T
authors: Kumagai
authors: Takako
authors: T
authors: Okuyama
authors: Jiro
authors: J
authors: Okami
authors: Masahiko
authors: M
authors: Higashiyama
authors: Ken
authors: K
authors: Kodama
authors: Fumio
authors: F
authors: Imamura
authors: Kikuya
authors: K
authors: Kato
mesh_terms: D000230:Adenocarcinoma / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019943:Amino Acid Substitution; D004252:DNA Mutational Analysis / Q000379:methods*; D004273:DNA, Neoplasm / Q000097:blood / Q000235:genetics*; D066246:ErbB Receptors / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D006801:Humans; D008175:Lung Neoplasms / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D004273:DNA, Neoplasm; D066246:ErbB Receptors