title: Radiation Therapy is Associated with Improved Outcomes in Merkel Cell Carcinoma.
abstract: Following wide excision of Merkel cell carcinoma (MCC), postoperative radiation therapy (RT) is typically recommended. Controversy remains as to whether RT can be avoided in selected cases, such as those with negative margins. Additionally, there is evidence that RT can influence survival.
  
  
  
  We included 171 patients treated for non-metastatic MCC from 1994 through 2012 at a single institution. Patients without pathologic nodal evaluation (clinical N0 disease) were excluded to reflect modern treatment practice. The endpoints included local control (LC), locoregional control (LRC), disease-free survival (DFS), overall survival (OS), and disease-specific survival (DSS).
  
  
  
  Median follow-up was 33 months. Treatment with RT was associated with improved 3-year LC (91.2 vs. 76.9 %, respectively; p = 0.01), LRC (79.5 vs. 59.1 %; p = 0.004), DFS (57.0 vs. 30.2 %; p < 0.001), and OS (73 vs. 66 %; p = 0.02), and was associated with improved 3-year DSS among node-positive patients (76.2 vs. 48.1 %; p = 0.035), but not node-negative patients (90.1 vs. 80.8 %; p = 0.79). On multivariate analysis, RT was associated with improved LC [hazard ratio (HR) 0.18, 95 % confidence interval (CI) 0.07-0.46; p < 0.001], LRC (HR 0.28, 95 % CI 0.14-0.56; p < 0.001), DFS (HR 0.42, 95 % CI 0.26-0.70; p = 0.001), OS (HR 0.53, 95 % CI 0.31-0.93; p = 0.03), and DSS (HR 0.42, 95 % CI 0.26-0.70; p = 0.001). Patients with negative margins had significant improvements in 3-year LC (90.1 vs. 75.4 %; p < 0.001) with RT. Deaths not attributable to MCC were relatively evenly distributed between the RT and no RT groups (28.5 and 29.3 % of patients, respectively).
  
  
  
  RT for MCC was associated with improved LRC and survival. RT appeared to be beneficial regardless of margin status.
authors.affiliation: Department of Radiation Oncology, H. Lee Moffitt Cancer Center, Tampa, FL, USA.
authors.forename: Tobin
authors.initials: T
authors.lastname: Strom
authors.affiliation: School of Medicine, University of South Florida Morsani College of Medicine, Tampa, FL, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Carr
authors.affiliation: Department of Cutaneous Oncology, Moffitt Cancer Center, Tampa, FL, USA.|Departments of Oncologic Sciences and Surgery, University of South Florida Morsani College of Medicine, Tampa, FL, USA.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Zager
authors.affiliation: Department of Radiation Oncology, H. Lee Moffitt Cancer Center, Tampa, FL, USA.
authors.forename: Arash
authors.initials: A
authors.lastname: Naghavi
authors.affiliation: Department of Cutaneous Oncology, Moffitt Cancer Center, Tampa, FL, USA.|Departments of Oncologic Sciences and Surgery, University of South Florida Morsani College of Medicine, Tampa, FL, USA.
authors.forename: Franz O
authors.initials: FO
authors.lastname: Smith
authors.affiliation: Department of Cutaneous Oncology, Moffitt Cancer Center, Tampa, FL, USA.|Departments of Oncologic Sciences and Surgery, University of South Florida Morsani College of Medicine, Tampa, FL, USA.
authors.forename: C Wayne
authors.initials: CW
authors.lastname: Cruse
authors.affiliation: Department of Cutaneous Oncology, Moffitt Cancer Center, Tampa, FL, USA.|Departments of Pathology & Cell Biology and Dermatology, University of South Florida Morsani College of Medicine, Tampa, FL, USA.
authors.forename: Jane L
authors.initials: JL
authors.lastname: Messina
authors.affiliation: Department of Head and Neck and Endocrine Oncology, Moffitt Cancer Center, Tampa, FL, USA.
authors.forename: Jeffery
authors.initials: J
authors.lastname: Russell
authors.affiliation: Department of Radiation Oncology, H. Lee Moffitt Cancer Center, Tampa, FL, USA.
authors.forename: Nikhil G
authors.initials: NG
authors.lastname: Rao
authors.affiliation: Department of Biostatistics, Moffitt Cancer Center, Tampa, FL, USA.
authors.forename: William
authors.initials: W
authors.lastname: Fulp
authors.affiliation: Department of Radiation Oncology, H. Lee Moffitt Cancer Center, Tampa, FL, USA.
authors.forename: Sungjune
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, H. Lee Moffitt Cancer Center, Tampa, FL, USA.
authors.forename: Javier F
authors.initials: JF
authors.lastname: Torres-Roca
authors.affiliation: Department of Head and Neck and Endocrine Oncology, Moffitt Cancer Center, Tampa, FL, USA.
authors.forename: Tapan A
authors.initials: TA
authors.lastname: Padhya
authors.affiliation: Department of Cutaneous Oncology, Moffitt Cancer Center, Tampa, FL, USA.|Departments of Oncologic Sciences and Surgery, University of South Florida Morsani College of Medicine, Tampa, FL, USA.
authors.forename: Vernon K
authors.initials: VK
authors.lastname: Sondak
authors.affiliation: Department of Radiation Oncology, H. Lee Moffitt Cancer Center, Tampa, FL, USA.
authors.forename: Andy M
authors.initials: AM
authors.lastname: Trotti
authors.affiliation: Department of Radiation Oncology, H. Lee Moffitt Cancer Center, Tampa, FL, USA. louis.harrison@moffitt.org.
authors.forename: Louis B
authors.initials: LB
authors.lastname: Harrison
authors.affiliation: Department of Radiation Oncology, H. Lee Moffitt Cancer Center, Tampa, FL, USA. jimmy.caudell@moffitt.org.
authors.forename: Jimmy J
authors.initials: JJ
authors.lastname: Caudell
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015266:Carcinoma, Merkel Cell / Q000532:radiotherapy* / Q000556:secondary / Q000601:surgery*; D018572:Disease-Free Survival; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis; D008297:Male; D000072662:Margins of Excision; D008875:Middle Aged; D018714:Radiotherapy, Adjuvant; D012189:Retrospective Studies; D021701:Sentinel Lymph Node Biopsy; D012878:Skin Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D015996:Survival Rate