title: The performance of a novel amino acid multivariate index for detecting lung cancer: A case control study in Korea.
abstract: BACKGROUND
  Previous studies have shown that plasma free amino acid (PFAA) profiles are altered in cancer patients compared with healthy controls. A multivariate index based on PFAAs was generated from a Japanese dataset and has been previously demonstrated to be clinically valuable for discriminating patients in the early stages of lung cancer. However, it remains unclear whether similar PFAA profile changes occur in cancer patients from other populations. Therefore, this study aimed to validate the performance of this index in discriminating lung cancer patients from controls in the Korean population.
  
  
  METHODS
  Samples were collected from a total of 142 Korean subjects (72 lung cancer/70 controls) for this study. PFAAs were quantified by high-performance liquid chromatography-electrospray ionization-mass spectrometry, and the clinical performance characteristics of the amino acid multivariate index were evaluated across cancer stages and histological types.
  
  
  RESULTS
  The concentrations of several PFAAs were significantly decreased in the Korean lung cancer patients compared with the controls. Significant decreases in threonine, citrulline, histidine and tryptophan and increases in proline, isoleucine, phenylalanine and ornithine were observed, which are similar to the PFAA changes reported by a previous Japanese study. The area under the receiver-operator characteristic curve (AUC of the ROC) for the index was 0.80, and similar performances were demonstrated for the different histological types.
  
  
  CONCLUSIONS
  These results suggest that the amino acid multivariate index previously developed from a Japanese dataset has the potential to aid in the early detection of lung cancers of different histological types in Korean patients.
authors.affiliation: Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Republic of Korea.
authors.forename: Hee Joung
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Hallym University Sacred Heart Hospital, Anyang, Republic of Korea.
authors.forename: Seung Hun
authors.initials: SH
authors.lastname: Jang
authors.affiliation: Department of Internal Medicine, Inha University Hospital, Incheon, Republic of Korea.
authors.forename: Jeong-Seon
authors.initials: JS
authors.lastname: Ryu
authors.affiliation: Department of Internal Medicine, Chungnam National University Hospital and Cancer Research Institute, Deajon, Republic of Korea.
authors.forename: Jeong Eun
authors.initials: JE
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Hwasun Hospital, Hwasun, Republic of Korea.
authors.forename: Young Chul
authors.initials: YC
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Pusan National University Hospital, Pusan, Republic of Korea.
authors.forename: Min Ki
authors.initials: MK
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Kosin University Medical College, Pusan, Republic of Korea.
authors.forename: Tae Won
authors.initials: TW
authors.lastname: Jang
authors.affiliation: Department of Internal Medicine, Kyungpook National University Hospital, Daegu, Republic of Korea.
authors.forename: Shin-Yup
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Institute for Innovation, Ajinomoto Co., Inc., Kawasaki, Japan.
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Nakamura
authors.affiliation: Institute for Innovation, Ajinomoto Co., Inc., Kawasaki, Japan.
authors.forename: Natsumi
authors.initials: N
authors.lastname: Nishikata
authors.affiliation: Institute for Innovation, Ajinomoto Co., Inc., Kawasaki, Japan.
authors.forename: Maiko
authors.initials: M
authors.lastname: Mori
authors.affiliation: Institute for Innovation, Ajinomoto Co., Inc., Kawasaki, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Noguchi
authors.affiliation: Institute for Innovation, Ajinomoto Co., Inc., Kawasaki, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyano
authors.affiliation: Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Republic of Korea. Electronic address: kyleemd@kuh.ac.kr.
authors.forename: Kye Young
authors.initials: KY
authors.lastname: Lee
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000596:Amino Acids / Q000097:blood*; D015415:Biomarkers; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000097:blood* / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012372:ROC Curve; D015203:Reproducibility of Results; D056910:Republic of Korea; D012307:Risk Factors
chemical_list: D000596:Amino Acids; D015415:Biomarkers
keywords: Early detection; Lung cancer; Plasma free amino acid