title: Prognostic impact of circulating tumor cells in patients with small cell lung cancer.
abstract: BACKGROUND
  Enumeration of circulating tumor cells (CTCs) may be valuable for prognostic assessment in lung cancer patients. In this study, we report the clinical significance of CTCs in small cell lung cancer (SCLC).
  
  
  METHODS
  In total, 51 consecutive patients newly diagnosed as having SCLC and starting chemotherapy or chemoradiotherapy were prospectively enrolled. Blood samples were drawn at the baseline, after chemotherapy, and at relapse. CTCs were isolated using the CellSearch System (Veridex LLC). Thresholds of 1 to 100 cells at the baseline were systematically correlated with the overall survival. The optimal cutoff was determined by comparing the Cox proportional hazard ratios (HRs).
  
  
  RESULTS
  Two or more CTCs were detected at baseline in 35 patients (68.6%; 95% confidence interval, 55.0-79.7). The HR signifying the difference between the unfavorable (more than or equal to threshold) and favorable (less than threshold) groups was maximal at the threshold of 8 CTCs (HR, 3.50; 95% confidence interval, 1.45-8.60). Patients with ≥8 CTCs had worse survival than those with <8 CTCs at baseline (p = 0.0014). Patients with ≥8 CTCs posttreatment or at relapse also showed worse survival than those with <8 CTCs (p = 0.0096 and <0.0001). Patients whose baseline and posttreatment CTC levels remained <8 tended to show better survival than those whose CTC level converted from ≥8 to <8 cells (p = 0.0288) or whose posttreatment CTC level was ≥8 cells (p = 0.0047).
  
  
  CONCLUSIONS
  CTCs were highly detectable in SCLC, and higher CTC levels were strongly associated with worse survival. Consistently favorable CTC levels were associated with favorable outcomes.
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, Shizuoka Prefecture, Japan.
authors.forename: Tateaki
authors.initials: T
authors.lastname: Naito
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Tanaka
authors.forename: Akira
authors.initials: A
authors.lastname: Ono
authors.forename: Kazue
authors.initials: K
authors.lastname: Yoneda
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Takahashi
authors.forename: Haruyasu
authors.initials: H
authors.lastname: Murakami
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Asuka
authors.initials: A
authors.lastname: Tsuya
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Kenmotsu
authors.forename: Takehito
authors.initials: T
authors.lastname: Shukuya
authors.forename: Kyoichi
authors.initials: K
authors.lastname: Kaira
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Koh
authors.forename: Masahiro
authors.initials: M
authors.lastname: Endo
authors.forename: Seiki
authors.initials: S
authors.lastname: Hasegawa
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Yamamoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D001859:Bone Neoplasms / Q000097:blood / Q000401:mortality / Q000556:secondary*; D001932:Brain Neoplasms / Q000097:blood / Q000401:mortality / Q000556:secondary*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008113:Liver Neoplasms / Q000097:blood / Q000401:mortality / Q000556:secondary*; D008175:Lung Neoplasms / Q000097:blood / Q000401:mortality / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009360:Neoplastic Cells, Circulating / Q000473:pathology*; D011379:Prognosis; D011446:Prospective Studies; D055752:Small Cell Lung Carcinoma / Q000097:blood / Q000401:mortality / Q000473:pathology*; D015996:Survival Rate
chemical_list: D014408:Biomarkers, Tumor