title: Somatostatin Receptors 2A and 5 Are Expressed in Merkel Cell Carcinoma with No Association with Disease Severity.
abstract: OBJECTIVE
  Merkel cell carcinoma (MCC) is a rare high-grade neuroendocrine tumour of the skin. It has been speculated that MCCs express somatostatin receptors (SSTRs), but this has never been assessed in a large series of MCCs. The main aim of this study was to assess the expression of SSTR2A and SSTR5 in MCC tumours. The secondary aims were to assess whether expression of SSTR was associated with the Ki67 proliferative index, Merkel cell polyomavirus (MCPyV) status, clinical characteristics and outcome.
  
  
  METHODS
  Clinical data and tumours were collected from an ongoing cohort of French patients with MCC. Immunohistochemistry was performed with anti-SSTR2A and anti-SSTR5 monoclonal antibodies, and tumours were classified into 3 groups: 'no expression', 'low expression' and 'moderate expression' using an SSTR staining score.
  
  
  RESULTS
  SSTR expression was assessed for 105 MCC tissue samples from 98 patients, and clinical characteristics were available for 87 of them. SSTR expression was consistent between the primary skin tumour and the corresponding metastases for SSTR2A and SSTR5 in 3/7 and 6/7 cases, respectively. SSTR2A and SSTR5 were expressed in 58 cases (59.2%) and in 44 cases (44.9%), respectively. Overall, at least one SSTR was expressed in 75 tumours (76.5%). SSTR expression was not associated with clinical characteristics, Ki67 proliferative index, recurrence-free survival or MCC-specific survival. Expression of SSTR2A was associated with MCPyV status in MCC tumours but not SSTR5.
  
  
  CONCLUSIONS
  SSTRs were expressed in a high proportion of MCCs, although expression was heterogeneous between tumours and was not associated with disease severity.
authors.affiliation: Department of Pathology, University Hospital of Tours, Tours, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Gardair
authors.forename: Mahtab
authors.initials: M
authors.lastname: Samimi
authors.forename: Antoine
authors.initials: A
authors.lastname: Touzé
authors.forename: Pierre
authors.initials: P
authors.lastname: Coursaget
authors.forename: Gérard
authors.initials: G
authors.lastname: Lorette
authors.forename: Agnès
authors.initials: A
authors.lastname: Caille
authors.forename: Ewa
authors.initials: E
authors.lastname: Wierzbicka
authors.forename: Anne
authors.initials: A
authors.lastname: Croué
authors.forename: Martine
authors.initials: M
authors.lastname: Avenel-Audran
authors.forename: François
authors.initials: F
authors.lastname: Aubin
authors.forename: Rémy
authors.initials: R
authors.lastname: Kerdraon
authors.forename: Eric
authors.initials: E
authors.lastname: Estève
authors.forename: Nathalie
authors.initials: N
authors.lastname: Beneton
authors.forename: Serge
authors.initials: S
authors.lastname: Guyétant
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015266:Carcinoma, Merkel Cell / Q000378:metabolism* / Q000473:pathology; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D017481:Receptors, Somatostatin / Q000378:metabolism*; D012720:Severity of Illness Index; D012878:Skin Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D017481:Receptors, Somatostatin; C574734:SSTR2 protein, human; C094573:somatostatin receptor 5