title: The impact of the omission or inadequate dosing of radiotherapy in extranodal natural killer T-cell lymphoma, nasal type, in the United States.
abstract: BACKGROUND
  Extranodal natural killer T-cell lymphoma, nasal-type (NKTCL), is a rare malignancy in Western populations and is thus challenging for standardization of care and a prospective study. This study was aimed at defining patterns of care for NKTCL in the context of radiotherapy (RT) use and dose selection in the United States.
  
  
  METHODS
  Six hundred forty-two stage I-II NKTCL patients from 1998 to 2012 were identified from the National Cancer Data Base. Binary logistic regression analyses were performed to identify sociodemographic, treatment, and tumor characteristics predictive of the treatment selection and RT dose. Overall survival (OS) analyses were completed with the Kaplan-Meier and Cox multivariate methods, including a propensity score adjustment for a potential indication bias.
  
  
  RESULTS
  Of the 642 included NKTCL patients, 70% were at stage I, 79% were white, and 66% were ≤ 60 years old. Fifty-five percent received chemotherapy plus RT, 19% received RT alone, and 27% received chemotherapy alone. The median RT dose was 50 Gy (interquartile range, 43.2-54 Gy), 37% received < 45 Gy, and 43% received < 50 Gy. A multivariate survival analysis showed improved OS in comparison with chemotherapy alone for RT alone at ≥50 Gy (hazard ratio [HR], 0.41; 95% confidence interval [CI], 0.23-0.70; P < .01), for chemotherapy plus RT at <50 Gy (HR, 0.55, 95% CI, 0.36-0.86; P < .01), and for chemotherapy plus RT at ≥50 Gy (HR, 0.41; 95% CI, 0.27-0.63; P < .01).
  
  
  CONCLUSIONS
  Stage I-II NKTCL patients in the United States commonly receive chemotherapy alone or suboptimal-dose RT. The omission of RT or the use of suboptimal RT is negatively associated with OS. Efforts to continue improving evidenced-based management are warranted. Cancer 2017;123:3176-85. © 2017 American Cancer Society.
authors.affiliation: Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania.
authors.forename: John A
authors.identifier: http://orcid.org/0000-0002-0707-9239
authors.initials: JA
authors.lastname: Vargo
authors.affiliation: Division of Hematology and Oncology, Department of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania.
authors.forename: Arisha
authors.initials: A
authors.lastname: Patel
authors.affiliation: Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania.
authors.forename: Scott M
authors.initials: SM
authors.lastname: Glaser
authors.affiliation: Epidemiology Data Center, Department of Epidemiology, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania.
authors.forename: Goundappa K
authors.initials: GK
authors.lastname: Balasubramani
authors.affiliation: Division of Hematology and Oncology, Department of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania.
authors.forename: Rafic J
authors.initials: RJ
authors.lastname: Farah
authors.affiliation: Division of Hematology and Oncology, Department of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania.
authors.forename: Stanley M
authors.initials: SM
authors.lastname: Marks
authors.affiliation: Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania.
authors.forename: Sushil
authors.initials: S
authors.lastname: Beriwal
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001213:Asian / Q000706:statistics & numerical data; D003131:Combined Modality Therapy; D016208:Databases, Factual; D004522:Educational Status; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D054391:Lymphoma, Extranodal NK-T-Cell / Q000473:pathology / Q000628:therapy*; D008875:Middle Aged; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D057216:Propensity Score; D016016:Proportional Hazards Models; D011878:Radiotherapy / Q000379:methods / Q000706:statistics & numerical data; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods* / Q000706:statistics & numerical data; D012189:Retrospective Studies; D015996:Survival Rate; D014481:United States
keywords: 45 Gy; 50 Gy; National Cancer Data Base (NCDB); natural killer (NK) T-cell lymphoma; radiation dose response; radiation therapy