title: Clark level risk stratifies patients with mitogenic thin melanomas for sentinel lymph node biopsy.
abstract: BACKGROUND
  The role for sentinel lymph node biopsy (SLNB) in patients with thin melanoma (≤1 mm) remains controversial. We examined a large cohort of patients with thin melanoma to better define predictors of SLN positivity.
  
  
  METHODS
  From 1995 to 2011, 781 patients with thin primary melanoma and evaluable clinicopathologic data underwent SLNB at our institution. Predictors of SLN positivity were determined using univariate and multivariate regression analyses, and patients were risk-stratified using a classification and regression tree (CART) analysis.
  
  
  RESULTS
  In the study cohort (n = 781), 29 patients (3.7%) had nodal metastases. In the univariate analysis, mitotic rate [odds ratio (OR) = 8.11, p = 0.005], Clark level (OR 4.04, p = 0.003), and thickness (OR 3.33, p = 0.011) were significantly associated with SLN positivity. In the multivariate analysis, MR (OR 7.01) and level IV-V (OR 3.45) remained significant predictors of SLN positivity. CART analysis initially stratified lesions by mitotic rate; nonmitogenic lesions (n = 273) had a 0.7% SLN positivity rate versus 5.6% in mitogenic lesions (n = 425). Mitogenic lesions were further stratified by Clark level; patients with level II-III had a 2.9% SLN positivity rate (n = 205) versus 8.2% with level IV-V (n = 220). With median follow-up of 6.3 years, five SLN-negative patients developed nodal recurrence and four SLN-positive patients died of disease.
  
  
  CONCLUSIONS
  SLN positivity is low in patients with thin melanoma (3.7%) and exceedingly so in nonmitogenic lesions (0.7%). Appreciable rates of SLN positivity can be identified in patients with mitogenic lesions, particularly with concurrent level IV-V regardless of thickness. These factors may guide appropriate selection of patients with thin melanoma for SLNB.
authors.affiliation: Department of Surgery, Hospital of the University of Pennsylvania, University of Pennsylvania, Philadelphia, PA, USA, Edmund.Bartlett@uphs.upenn.edu.
authors.forename: Edmund K
authors.initials: EK
authors.lastname: Bartlett
authors.forename: Phyllis A
authors.initials: PA
authors.lastname: Gimotty
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Sinnamon
authors.forename: Heather
authors.initials: H
authors.lastname: Wachtel
authors.forename: Robert E
authors.initials: RE
authors.lastname: Roses
authors.forename: Lynn
authors.initials: L
authors.lastname: Schuchter
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Xu
authors.forename: David E
authors.initials: DE
authors.lastname: Elder
authors.forename: Michael
authors.initials: M
authors.lastname: Ming
authors.forename: Rosalie
authors.initials: R
authors.lastname: Elenitsas
authors.forename: DuPont
authors.initials: D
authors.lastname: Guerry
authors.forename: Rachel R
authors.initials: RR
authors.lastname: Kelz
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Czerniecki
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Fraker
authors.forename: Giorgos C
authors.initials: GC
authors.lastname: Karakousis
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008545:Melanoma / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D008938:Mitosis; D009367:Neoplasm Staging; D011379:Prognosis; D018570:Risk Assessment; D021701:Sentinel Lymph Node Biopsy; D012878:Skin Neoplasms / Q000556:secondary* / Q000601:surgery; D047368:Tumor Burden; D055815:Young Adult