title: Doses to carotid arteries after modern radiation therapy for Hodgkin lymphoma: is stroke still a late effect of treatment?
abstract: OBJECTIVE
  Hodgkin lymphoma (HL) survivors are at an increased risk of stroke because of carotid artery irradiation. However, for early-stage HL involved node radiation therapy (INRT) reduces the volume of normal tissue exposed to high doses. Here, we evaluate 3-dimensional conformal radiation therapy (3D-CRT), volumetric-modulated arc therapy (VMAT), and proton therapy (PT) delivered as INRT along with the extensive mantle field (MF) by comparing doses to the carotid arteries and corresponding risk estimates.
  
  
  METHODS
  We included a cohort of 46 supradiaphragmatic stage I-II classical HL patients. All patients were initially treated with chemotherapy and INRT delivered as 3D-CRT (30 Gy). For each patient, we simulated MF (36 Gy) and INRT plans using VMAT and PT (30 Gy). Linear dose-response curves for the 20-, 25-, and 30-year risk of stroke were derived from published HL data. Risks of stroke with each technique were calculated for all patients. Statistical analyses were performed with repeated measures analysis of variance.
  
  
  RESULTS
  The mean doses to the right and left common carotid artery were significantly lower with modern treatment compared with MF, with substantial patient variability. The estimated excess risk of stroke after 20, 25, and 30 years was 0.6%, 0.86%, and 1.3% for 3D-CRT; 0.67%, 0.96%, and 1.47% for VMAT; 0.61%, 0.96%, and 1.33% for PT; and 1.3%, 1.72%, and 2.61% for MF.
  
  
  CONCLUSIONS
  INRT reduces the dose delivered to the carotid arteries and corresponding estimated risk of stroke for HL survivors. Even for the subset of patients with lymphoma close to the carotid arteries, the estimated risk is low.
authors.affiliation: Department of Radiation Oncology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. dra.maraldo@gmail.com
authors.forename: Maja V
authors.initials: MV
authors.lastname: Maraldo
authors.forename: Patrick
authors.initials: P
authors.lastname: Brodin
authors.forename: Marianne C
authors.initials: MC
authors.lastname: Aznar
authors.forename: Ivan R
authors.initials: IR
authors.lastname: Vogelius
authors.forename: Per
authors.initials: P
authors.lastname: Munck af Rosenschöld
authors.forename: Peter M
authors.initials: PM
authors.lastname: Petersen
authors.forename: Lena
authors.initials: L
authors.lastname: Specht
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002339:Carotid Arteries / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006689:Hodgkin Disease / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk / Q000528:radiation effects*; D061766:Proton Therapy / Q000009:adverse effects; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects* / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods; D018570:Risk Assessment; D020521:Stroke / Q000209:etiology*; D017741:Survivors; D013997:Time Factors; D055815:Young Adult