title: DNA damaging effects of the dyes used in sentinel node biopsy: possible implications for clinical practice.
abstract: OBJECTIVE
  This study investigates whether methylene blue (MB), patent blue V (PBV), and indigo carmine (IDC) commonly used in sentinel node biopsy cause DNA damage to breast epithelial cells in vitro.
  
  
  METHODS
  MCF-7 and HB-2 cells were exposed for 5 minutes to the above dyes at the same concentrations used in clinical practice. Following exposure, the comet assay was performed to detect DNA damage. The enzyme, Fapy-DNA glycosylase (FpG) was incorporated to enable the detection of additional oxidative damage.
  
  
  RESULTS
  Both PBV and MB stimulated DNA strand breaks in both MCF-7 and HB2 cell lines (P < 0.05). Levels were elevated over 3-fold (P < 0.05) in MCF-7 and HB2 cells treated with 2.5% PBV and 1% MB, compared with untreated control cells. In contrast, IDC did not stimulate DNA strand break damage at clinically relevant concentrations in either cell line. Addition of Fapy-DNA glycosylase enzyme also revealed significantly (P < 0.05) increased levels of oxidative DNA lesions (ODL) in MCF-7 cells treated with PBV (17.6% ODL) compared with control cells (5.9% ODL).
  
  
  CONCLUSIONS
  This study shows, for the first time, that certain dyes (MB and PBV) commonly used in SLNB have genotoxic effects on breast cells at clinically relevant concentrations in vitro. In vivo studies are now warranted to assess and minimize DNA damage caused by these dyes during SLNB.
authors.affiliation: The Breast Unit, Department of Surgery, Leeds General Infirmary, Great George Street, Leeds, United Kingdom.
authors.forename: Yazan Adnan
authors.initials: YA
authors.lastname: Masannat
authors.forename: Andrew
authors.initials: A
authors.lastname: Hanby
authors.forename: Kieran
authors.initials: K
authors.lastname: Horgan
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Hardie
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology*; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D004396:Coloring Agents / Q000633:toxicity*; D004249:DNA Damage; D004847:Epithelial Cells / Q000187:drug effects / Q000473:pathology*; D006801:Humans; D066298:In Vitro Techniques; D007203:Indigo Carmine / Q000633:toxicity; D008751:Methylene Blue / Q000633:toxicity; D012394:Rosaniline Dyes / Q000633:toxicity; D021701:Sentinel Lymph Node Biopsy
chemical_list: D004396:Coloring Agents; D012394:Rosaniline Dyes; D007203:Indigo Carmine; C008769:sulfan blue; D008751:Methylene Blue