title: Negative Sentinel Lymph Node Biopsy in Merkel Cell Carcinoma is Associated with a Low Risk of Same-Nodal-Basin Recurrences.
abstract: BACKGROUND
  Controversy exists regarding the predictive ability of a negative sentinel lymph node biopsy (SLNB) and the use of adjuvant radiation in Merkel cell carcinoma (MCC).
  
  
  METHODS
  Retrospective study of patients with MCC undergoing SLNB at Mayo Clinic from 1995 to 2011. Cumulative incidence (CI) of regional recurrence and death from MCC, respectively, were estimated taking into account the competing risk of death from other causes and compared between groups using Gray's test.
  
  
  RESULTS
  A total of 111 (74 %) of 150 SLNB were negative and comprised our study group. There were 15 regional recurrences, and the CI of a regional recurrence was 5.1, 15.0, and 16.6 % at 1, 3, and 5 years, respectively, after initial surgery. Nine patients (8 % of all patients) experienced a same nodal basin recurrence after a negative SLNB. Among 14 patients who received nodal radiation, the CI of a regional recurrence was 0 and 9.1 % at 1 and 3 years, respectively, compared to 5.8 and 15.5 %, respectively, among the 97 who did not receive nodal radiation (p = 0.45). Male sex was the only characteristic predictive of regional recurrence after a negative SLNB; the CI at 3 years was 21.3 versus 0 % in men and women, respectively (p = 0.007). Head and neck location was not associated with a higher risk of recurrence or an improvement in regional recurrences after radiation.
  
  
  CONCLUSIONS
  Same nodal basin recurrences are uncommon after SLNB in MCC, and regional nodal irradiation can be avoided in the setting of successful sentinel lymph node mapping and a negative SLNB.
authors: Department of Surgery, Mayo Clinic Rochester, Rochester, MN, USA.
authors: Travis E
authors: TE
authors: Grotz
authors: Department of Medical Oncology, Mayo Clinic Jacksonville, Jacksonville, FL, USA.
authors: Richard W
authors: RW
authors: Joseph
authors: Department of Surgery, Mayo Clinic Scottsdale, Scottsdale, AZ, USA.
authors: Barbara A
authors: BA
authors: Pockaj
authors: Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, MN, USA.
authors: Robert L
authors: RL
authors: Foote
authors: Department of Dermatology, Mayo Clinic Rochester, Rochester, MN, USA.
authors: Clark C
authors: CC
authors: Otley
authors: Department of Surgery, Mayo Clinic Jacksonville, Jacksonville, FL, USA.
authors: Sanjay P
authors: SP
authors: Bagaria
authors: Department of Health Sciences Research, Mayo Clinic Rochester, Rochester, MN, USA.
authors: Amy L
authors: AL
authors: Weaver
authors: Department of Surgery, Mayo Clinic Rochester, Rochester, MN, USA. jakub.james@mayo.edu.
authors: James W
authors: JW
authors: Jakub
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015266:Carcinoma, Merkel Cell / Q000532:radiotherapy* / Q000556:secondary* / Q000601:surgery; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D015994:Incidence; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology*; D018714:Radiotherapy, Adjuvant; D012189:Retrospective Studies; D012307:Risk Factors; D021701:Sentinel Lymph Node Biopsy; D012878:Skin Neoplasms / Q000473:pathology* / Q000532:radiotherapy* / Q000601:surgery; D015996:Survival Rate; D013997:Time Factors