title: Identification of Patients with Intermediate Thickness Melanoma at Low Risk for Sentinel Lymph Node Positivity.
abstract: BACKGROUND
  Sentinel lymph node (SLN) biopsy is recommended for all patients with intermediate-thickness melanomas. We sought to identify such patients at low risk of SLN positivity.
  
  
  METHODS
  All patients with intermediate-thickness melanomas (1.01-4 mm) undergoing SLN biopsy at a single institution from 1995-2011 were included in this retrospective cohort study. Univariate and multivariate logistic regression determined factors associated with a low risk of SLN positivity. Classification and regression tree (CART) analysis was used to stratify groups based on risk of positivity.
  
  
  RESULTS
  Of the 952 study patients, 157 (16.5 %) had a positive SLN. In the multivariate analysis, thickness <1.5 mm (odds ratio [OR] 0.29), age ≥60 (OR 0.69), present tumor-infiltrating lymphocytes (OR 0.60), absent lymphovascular invasion (OR 0.46), and absent satellitosis (OR 0.44) were significantly associated with a low risk of SLN positivity. CART analysis identified thickness of 1.5 mm as the primary cut point for risk of SLN metastasis. Patients with a thickness of <1.5 mm represented 36 % of the total cohort and had a SLN positivity rate of 6.6 % (95 % confidence interval 3.8-9.4 %). In patients with melanomas <1.5 mm in thickness, the presence of additional low risk factors identified 257 patients (75 % of patients with <1.5 mm melanomas) in which the rate of SLN positivity was <5 %.
  
  
  CONCLUSIONS
  Despite a SLN positivity rate of 16.5 % overall, substantial heterogeneity of risk exists among patients with intermediate-thickness melanoma. Most patients with melanoma between 1.01 and 1.5 mm have a risk of SLN positivity similar to that in patients with thin melanomas.
authors.affiliation: Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, USA. edmund.bartlett@uphs.upenn.edu.
authors.forename: Edmund K
authors.initials: EK
authors.lastname: Bartlett
authors.affiliation: Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, USA.
authors.forename: Madalyn G
authors.initials: MG
authors.lastname: Peters
authors.affiliation: Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, USA.
authors.forename: Anne
authors.initials: A
authors.lastname: Blair
authors.affiliation: Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, USA.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Etherington
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Elder
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, USA.
authors.forename: Xiaowei G
authors.initials: XG
authors.lastname: Xu
authors.affiliation: Hematology-Oncology Division, Department of Medicine, University of Pennsylvania, Philadelphia, USA.
authors.forename: DuPont
authors.initials: D
authors.lastname: Guerry
authors.affiliation: Department of Dermatology, University of Pennsylvania, Philadelphia, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Ming
authors.affiliation: Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, USA.
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Fraker
authors.affiliation: Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Czerniecki
authors.affiliation: Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, USA.
authors.forename: Phyllis A
authors.initials: PA
authors.lastname: Gimotty
authors.affiliation: Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, USA. Giorgos.Karakousis@uphs.upenn.edu.
authors.forename: Giorgos C
authors.initials: GC
authors.lastname: Karakousis
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D016246:Lymphocytes, Tumor-Infiltrating / Q000473:pathology*; D008297:Male; D008545:Melanoma / Q000145:classification / Q000473:pathology*; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology*; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D021701:Sentinel Lymph Node Biopsy; D012878:Skin Neoplasms / Q000145:classification / Q000473:pathology*