title: Multiple primary malignancies in patients with Merkel cell carcinoma.
abstract: BACKGROUND
  Merkel cell carcinoma (MCC) is a rare malignant cutaneous tumour, the incidence of which is increasing. Second malignancies have been reported to occur with high incidence in these patients.
  
  
  OBJECTIVE
  We report the rate and nature of multiple malignancies in patients with MCC treated over a 10 year period in Addenbrooke's Hospital in Cambridge, United Kingdom, as well as the temporal relationship of these additional malignancies to the diagnosis of MCC.
  
  
  RESULTS
  The 27 patients had an approximately equal sex incidence with a median age at diagnosis of 79 years. Seventy percent (n=19) of patients had a second primary malignant tumour; and 7 of these patients had two or more tumours in addition to the MCC. Eighteen patients had additional cutaneous malignancies: melanoma, squamous cell carcinoma and basal cell carcinoma, and 8 patients presented non-cutaneous malignancy including colorectal, haematological and breast tumours. Of the 28 additional tumours in our patients, half were diagnosed prior to presentation of MCC, 32% within 6 months of diagnosis, and 18% between 6 months and 3 years after diagnosis. Possible reasons for the high rate of additional tumours in this population are discussed.
  
  
  CONCLUSIONS
  Our figures reflect a higher incidence of multiple malignancies in those with Merkel cell tumour than has previously been reported. This has important implications for the care and surveillance of these patients.
authors.affiliation: Department of Dermatology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: J K
authors.initials: JK
authors.lastname: Gass
authors.forename: S K
authors.initials: SK
authors.lastname: Chan
authors.forename: E
authors.initials: E
authors.lastname: Rytina
authors.forename: D C
authors.initials: DC
authors.lastname: Greenberg
authors.forename: N P
authors.initials: NP
authors.lastname: Burrows
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015266:Carcinoma, Merkel Cell / Q000150:complications*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000150:complications*; D012878:Skin Neoplasms / Q000150:complications*; D006113:United Kingdom