title: Increasing tumor thickness is associated with recurrence and poorer survival in patients with Merkel cell carcinoma.
abstract: BACKGROUND
  Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous neuroendocrine tumor usually occurring on sun-exposed skin in elderly patients. Clinical and pathologic factors associated with disease progression and mortality in patients with MCC are poorly defined. Recently, it has been reported that p63 expression in primary MCC is strongly associated with clinical outcome.
  
  
  METHODS
  MCC patients diagnosed between July 1, 1993 and July 31, 2009 were identified from the surgical pathology records of the Sydney South West Area Health Service. Clinical, pathologic, treatment, and survival data were obtained and immunohistochemical analyses for p53, p63, and Ki-67 were performed. The associations of clinical and pathologic features with disease-free and disease-specific survival were analyzed.
  
  
  RESULTS
  Ninety-five patients were identified (67 males, 28 females; median age at diagnosis of primary MCC 76 [range, 42-93] years). Increasing primary tumor thickness was significantly associated with poorer disease-free survival (5-year survival 18 % in tumors >10 mm thick compared with 69 % for patients with tumors ≤10 mm thick, p = 0.002) and disease-specific survival (5-year survival 74 % in tumors >10 mm thick compared with 97 % for patients with tumors ≤10 mm thick, p = 0.006). There was a strong positive correlation between the Ki-67 index (proportion of Ki-67-positive tumor nuclei) and tumor thickness (r = 0.39, n = 45, p = 0.008). Positive staining for p63 in MCC was infrequent (9 % of primary MCC) and showed no significant association with disease outcome.
  
  
  CONCLUSIONS
  Tumor thickness is significantly associated with disease-free survival in MCC. We recommend that primary tumor thickness be routinely recorded in the pathology reports of patients with primary MCC.
authors: Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.
authors: Cathy S
authors: CS
authors: Lim
authors: Deborah
authors: D
authors: Whalley
authors: Lauren E
authors: LE
authors: Haydu
authors: Rajmohan
authors: R
authors: Murali
authors: Jill
authors: J
authors: Tippett
authors: John F
authors: JF
authors: Thompson
authors: George
authors: G
authors: Hruby
authors: Richard A
authors: RA
authors: Scolyer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015266:Carcinoma, Merkel Cell / Q000378:metabolism / Q000473:pathology*; D018572:Disease-Free Survival; D005260:Female; D006258:Head and Neck Neoplasms / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D053208:Kaplan-Meier Estimate; D019394:Ki-67 Antigen / Q000378:metabolism; D035002:Lower Extremity; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008875:Middle Aged; D008940:Mitotic Index; D009364:Neoplasm Recurrence, Local / Q000378:metabolism / Q000473:pathology*; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D034941:Upper Extremity
chemical_list: C081876:CKAP4 protein, human; D019394:Ki-67 Antigen; D008565:Membrane Proteins; D016159:Tumor Suppressor Protein p53