title: Second nonmelanoma skin cancer in Spain: frequency and chronology.
abstract: BACKGROUND
  Follow-up of patients with nonmelanoma skin cancer (NMSC) is mainly aimed at the early diagnosis of local recurrences and early detection of a subsequent or second NMSC (sNMSC). However, the frequency and chronology of sNMSC have not been widely studied in the literature.
  
  
  OBJECTIVE
  To assess the frequency and chronology of developing an sNMSC.
  
  
  METHODS
  This was a retrospective longitudinal study of patients with a first NMSC excised and diagnosed at the Hospital Universitario Virgen Macarena (Seville, Spain) between 1 January 1998 and 31 December 2000 and followed up until 31 December 2009. Age, sex, histological type of NMSC (basal cell carcinoma, squamous cell carcinoma), anatomical location, and the diagnosis date of both the first NMSC and the sNMSC were recorded. Main outcomes assessed were the frequency of developing an sNMSC, the annual probability density and the median sNMSC-free survival through the Kaplan-Meier model.
  
  
  RESULTS
  A total of 926 patients with a first single NMSC were enrolled and followed up for a median time of 81.9 months. Two hundred and nine patients (22.6%) developed an sNMSC in a median time of 28.3 months. Probability density of a sNMSC ranged from 0.003 to 0.004 for the first 5 years of follow-up. Age ≥ 40 years (P = 0.02), and first NMSC excised from the limbs (P = 0.03) were predictors of developing an sNMSC.
  
  
  CONCLUSIONS
  The development of an sNMSC is a common event in patients previously diagnosed with an NMSC especially during the first 5 years of follow-up. This finding should be taken into consideration when designing follow-up guidelines for patients with NMSC.
authors.affiliation: Research Unit, Dermatology Unit, Hospital Universitario Virgen Macarena, Avda Dr Fedriani s/n, 41009, Seville, Spain.
authors.forename: J J
authors.initials: JJ
authors.lastname: Domínguez-Cruz
authors.forename: A
authors.initials: A
authors.lastname: Nieto-García
authors.forename: J J
authors.initials: JJ
authors.lastname: Rios
authors.forename: D
authors.initials: D
authors.lastname: Moreno-Ramirez
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D012878:Skin Neoplasms / Q000453:epidemiology*; D013030:Spain / Q000453:epidemiology; D013997:Time Factors