title: Meta-analysis of superficial versus deep injection of radioactive tracer and blue dye for lymphatic mapping and detection of sentinel lymph nodes in breast cancer.
abstract: BACKGROUND
  Sentinel lymph node biopsy (SLNB) is the standard of care for axillary staging in early breast cancer. Currently, no consensus exists on the optimal site of injection of the radioactive tracer or blue dye.
  
  
  METHODS
  A systematic review and meta-analysis of studies comparing superficial and deep injections of radioactive tracer or blue dye for lymphatic mapping and SLNB was performed. The axillary and extra-axillary sentinel lymph node (SLN) identification rates obtained by lymphoscintigraphy and intraoperative SLNB were evaluated. Pooled odds ratios (ORs) and 95 per cent c.i. were estimated using fixed-effect analyses, or random-effects analyses if there was statistically significant heterogeneity (P < 0·050).
  
  
  RESULTS
  Thirteen studies were included in the meta-analysis. There was no significant difference between superficial and deep injections of radioactive tracer for axillary SLN identification on lymphoscintigraphy (OR 1·59, 95 per cent c.i. 0·79 to 3·17), during surgery (OR 1·27, 0·60 to 2·68) and for SLN identification using blue dye (OR 1·40, 0·83 to 2·35). The rate of extra-axillary SLN identification was significantly greater when deep rather than superficial injection was used (OR 3·00, 1·92 to 4·67). The discordance rate between superficial and deep injections ranged from 4 to 73 per cent for axillary and from 0 to 61 per cent for internal mammary node mapping.
  
  
  CONCLUSIONS
  Both superficial and deep injections of radioactive tracer and blue dye are effective for axillary SLN identification. Clinical consequences of discordance rates between the two injection techniques are unclear. Deep injections are associated with significantly greater extra-axillary SLN identification; however, this may not have a significant impact on clinical management.
authors.affiliation: Research Oncology, Division of Cancer Studies, King's College London, London.
authors.forename: M
authors.initials: M
authors.lastname: Ahmed
authors.forename: A D
authors.initials: AD
authors.lastname: Purushotham
authors.forename: K
authors.initials: K
authors.lastname: Horgan
authors.forename: J M
authors.initials: JM
authors.lastname: Klaase
authors.forename: M
authors.initials: M
authors.lastname: Douek
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology* / Q000601:surgery; D015331:Cohort Studies; D004396:Coloring Agents / Q000008:administration & dosage; D005260:Female; D006801:Humans; D061705:Image-Guided Biopsy / Q000379:methods; D007267:Injections; D007430:Intraoperative Care; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D061305:Lymphoscintigraphy / Q000379:methods; D011849:Radioactive Tracers; D011868:Radioisotopes / Q000008:administration & dosage; D016032:Randomized Controlled Trials as Topic; D021701:Sentinel Lymph Node Biopsy / Q000379:methods; D016896:Treatment Outcome
chemical_list: D004396:Coloring Agents; D011849:Radioactive Tracers; D011868:Radioisotopes