title: Single versus multiple primary melanomas: old questions and new answers.
abstract: BACKGROUND
  In patients with multiple primary melanomas (MPM), mean tumor thickness tends to decrease from the first melanoma to the second melanoma, and prognosis may be improved compared with the prognosis for patients who have a single primary melanoma (SPM). In this study, the authors compared the clinicopathologic features of patients with MPM and SPM to better characterize the differences between these 2 groups and to determine whether or not there is an inherent difference in tumor aggression.
  
  
  METHODS
  In total, 788 patients with melanoma who were enrolled prospectively in the Interdisciplinary Melanoma Cooperative Group database from 2002 to 2008 were studied. Patients with SPM and with MPM were compared with regard to clinical and primary melanoma characteristics.
  
  
  RESULTS
  Of 788 patients with melanoma, 61 patients (7.7%) had 2 or more primary melanomas. The incidence of developing a second primary melanoma 1 year and 5 years after initial melanoma diagnosis was 4.1% and 8.7%, respectively, and most of the risk accumulated within the first year. The incidence of MPM was greater in patients aged ≥60 years than in those aged ≤60 years. The absence or presence of mitosis and other tumor characteristics did not differ significantly between patients with SPM and patients with MPM (P = .61).
  
  
  CONCLUSIONS
  No difference was observed in the presence or absence of mitoses, a marker of tumor proliferation, in SPM and MPM. Because it has been demonstrated that the presence of mitosis is a powerful prognostic marker, the current findings suggested that the tumors behave similarly in patients with SPM and patients with MPM. The authors concluded that differences in tumor thickness and prognosis between SPM and MPM more likely are caused by factors other than tumor biology, such as increased surveillance.
authors.affiliation: Ronald O. Perelman Department of Dermatology, New York University School of Medicine, New York, New York, USA.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Hwa
authors.forename: Leah S
authors.initials: LS
authors.lastname: Price
authors.forename: Ilana
authors.initials: I
authors.lastname: Belitskaya-Levy
authors.forename: Michelle W
authors.initials: MW
authors.lastname: Ma
authors.forename: Richard L
authors.initials: RL
authors.lastname: Shapiro
authors.forename: Russell S
authors.initials: RS
authors.lastname: Berman
authors.forename: Hideko
authors.initials: H
authors.lastname: Kamino
authors.forename: Farbod
authors.initials: F
authors.lastname: Darvishian
authors.forename: Iman
authors.initials: I
authors.lastname: Osman
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Stein
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008545:Melanoma / Q000473:pathology*; D008875:Middle Aged; D008938:Mitosis; D009378:Neoplasms, Multiple Primary / Q000473:pathology*; D011379:Prognosis; D012878:Skin Neoplasms / Q000473:pathology*