title: Second-line therapy for small cell lung cancer: exploring the potential role of circulating tumor cells.
abstract: BACKGROUND
  Small cell lung cancer (SCLC) is an aggressive and invasive variant of lung tumors. SCLC, especially in advanced stages, is distinguished by extremely high numbers of circulating tumor cells (CTCs) in comparison to other malignancies. CTCs are operative in tumor spread and are currently enumerated to assess prognosis and response to cytotoxic therapy. Chemosensitivity of SCLC CTCs compared to primary tumors and metastases is not known.
  
  
  METHODS
  Establishment of two SCLC CTC cell lines, namely BHGc7 and BHGc10, allowed the in vitro characterization of their chemosensitivity to the second-line chemotherapeutics topotecan and epirubicin in comparison to a range of SCLC cell lines.
  
  
  RESULTS
  The SCLC CTC cell lines exhibited an approximately 7- and 12-fold increased chemosensitivity to epirubicin compared to topotecan, respectively, in in vitro cytotoxicity assays. In comparison to a panel of six SCLC cell lines, the two CTC lines showed a significantly higher chemosensitivity to epirubicin (range, 3- to 16-fold) and topotecan (range, 2.2- to 14.4-fold), respectively.
  
  
  CONCLUSIONS
  CTC cell lines derived from SCLC patients with recurrent disease exhibit high chemosensitivity to epirubicin vs. topotecan and show considerable more cytotoxicity in response to both compounds in comparison to a panel of SCLC cell lines. Thus, a decrease in the number of CTCs in response to second-line chemotherapy in SCLC patients may overestimate the effect on resident SCLC lesions and metastases.
authors.affiliation: 1 Department of Surgery, Medical University of Vienna, Vienna, Austria ; 2 Oncologic Respiratory Unit, Otto-Wagner Hospital, Vienna, Austria.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Hamilton
authors.affiliation: 1 Department of Surgery, Medical University of Vienna, Vienna, Austria ; 2 Oncologic Respiratory Unit, Otto-Wagner Hospital, Vienna, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Rath
authors.affiliation: 1 Department of Surgery, Medical University of Vienna, Vienna, Austria ; 2 Oncologic Respiratory Unit, Otto-Wagner Hospital, Vienna, Austria.
authors.forename: Sophia
authors.initials: S
authors.lastname: Holzer
authors.affiliation: 1 Department of Surgery, Medical University of Vienna, Vienna, Austria ; 2 Oncologic Respiratory Unit, Otto-Wagner Hospital, Vienna, Austria.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Hochmair
keywords: Small cell lung cancer (SCLC); chemosensitivity; chemotherapy; circulating tumor cells (CTCs); epirubicin; topotecan