title: Progastrin-releasing peptide as a diagnostic and therapeutic biomarker of small cell lung cancer.
abstract: BACKGROUND
  Progastrin-releasing peptide (proGRP) is a recently identified biomarker of small cell lung cancer (SCLC). We evaluated the usefulness of plasma proGRP level as a tumor marker for diagnosis and treatment monitoring in patients with SCLC.
  
  
  METHODS
  Plasma samples were collected prospectively from 452 [212 non-small cell lung cancer (NSCLC), 105 SCLC, and 135 other diseases] patients who visited the hospital for tissue diagnosis. Plasma proGRP levels were measured using a two-step automated immunoassay.
  
  
  RESULTS
  The median proGRP level was significantly higher in patients with SCLC (892.7 pg/mL) than those with NSCLC (32.6 pg/mL, P<0.001) and other diseases (26.6 pg/mL, P<0.001). At cutoff level of 63 pg/mL, proGRP shows 85.7% sensitivity, 90.2% specificity, 72.5% positive predictive value and 95.4% negative predictive value in patients with SCLC. The area under the curve values were 0.93 for distinguishing SCLC from NSCLC, and 0.943 for distinguishing SCLC from the other conditions. Median proGRP level was higher in extensive disease (1,055.2 pg/mL) than limited disease (253.8 pg/mL, P=0.005). Median OS was significantly shorter in patients with extensive disease (6.0±0.7 months) than limited disease (12.7±4.5 months, P<0.01). Among the 39 patients with SCLC who were followed, the median proGRP levels of the 23 responders decreased after chemotherapy (P<0.001).
  
  
  CONCLUSIONS
  Plasma proGRP level could be a useful diagnostic and therapeutic monitoring biomarker for patients with SCLC and the initial level may help with SCLC tumor staging.
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Hyung-Joo
authors.initials: HJ
authors.lastname: Oh
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Ha-Young
authors.initials: HY
authors.lastname: Park
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Ki-Hyun
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea;; Lung and Esophageal Cancer Clinic, Chonnam National University Hwasun Hospital, Jeonnam, Korea.
authors.forename: Cheol-Kyu
authors.initials: CK
authors.lastname: Park
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Hong-Joon
authors.initials: HJ
authors.lastname: Shin
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea;; Lung and Esophageal Cancer Clinic, Chonnam National University Hwasun Hospital, Jeonnam, Korea.
authors.forename: Jung-Hwan
authors.initials: JH
authors.lastname: Lim
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Yong-Soo
authors.initials: YS
authors.lastname: Kwon
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea;; Lung and Esophageal Cancer Clinic, Chonnam National University Hwasun Hospital, Jeonnam, Korea.
authors.forename: In-Jae
authors.initials: IJ
authors.lastname: Oh
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Yu-Il
authors.initials: YI
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Sung-Chul
authors.initials: SC
authors.lastname: Lim
authors.affiliation: Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea;; Lung and Esophageal Cancer Clinic, Chonnam National University Hwasun Hospital, Jeonnam, Korea.
authors.forename: Young-Chul
authors.initials: YC
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Soo-Hyun
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Myung-Geun
authors.initials: MG
authors.lastname: Shin
keywords: Progastrin-releasing peptide (proGRP); biomarker; small cell lung cancer (SCLC)