title: Dose-volume response in acute dysphagia toxicity: Validating QUANTEC recommendations into clinical practice for head and neck radiotherapy.
abstract: OBJECTIVE
  To determine the validity of QUANTEC recommendations in predicting acute dysphagia using intensity-modulated head and neck radiotherapy.
  
  
  METHODS
  Seventy-six consecutive patients with locally advanced squamous cell carcinoma (SCC) of the head and neck +/- systemic therapy were analyzed. Multiple dose parameters for the larynx (V50Gy, Dmean and Dmax) were recorded. Acute dysphagia toxicity was prospectively scored in all treatment weeks (week 1-6 or 1-7) using CTCAEv3 by three blinded investigators. QUANTEC larynx recommendations (V50Gy < 27%, Dmean < 44 Gy, Dmean < 40 Gy, Dmax < 66 Gy) were used to group the cohort (i.e. V50Gy < 27% vs. V50Gy > 27%). The proportion of patients with Grade 3 dysphagia was compared within each group.
  
  
  RESULTS
  There was a significant reduction in the incidence of grade 3 toxicity in the V50Gy < or > 27% group at week 5 (14.3% vs. 45.2%, p = 0.01) and 6 (25.9% vs. 65.9%, p < 0.01). A significant reduction at week 5 (14.7% vs. 50.0, p = 0.02) and 6 (32.4% vs. 67.6%, p = 0.01) was seen in Dmean < 44 Gy when compared to Dmean > 44 Gy. Dmean < 40 Gy also delivered a significant reduction at week 5 (5.6% vs. 42.3%, p < 0.01) and week 6 (23.5% vs. 59.3%, p = 0.01). A significant toxicity reduction at treatment week 6 (28.0% vs. 63.0%, p = 0 < 01) was seen from Dmax < 66 Gy to Dmax > 66 Gy. V50Gy > 27% (p < 0.01), Dmean > 40 Gy (p = 0.01) and Dmax > 66 Gy (p < 0.01) were also predictors of Grade 3 dysphagia when analyzed with multiple clinical risk factors.
  
  
  CONCLUSIONS
  QUANTEC late toxicity recommendations for dose to larynx during IMRT are a useful predictor for acute dysphagia toxicity in this patient cohort. Furthermore, this included chemoradiotherapy regimes and post-operative radiotherapy patients, allowing for prophylactic implementation of supportive care measures.
authors: Department of Radiation Oncology, Austin Health, Heidelberg Heights , Victoria , Australia.
authors: Nigel J
authors: NJ
authors: Anderson
authors: Morikatsu
authors: M
authors: Wada
authors: Michal
authors: M
authors: Schneider-Kolsky
authors: Maureen
authors: M
authors: Rolfo
authors: Daryl Lim
authors: DL
authors: Joon
authors: Vincent
authors: V
authors: Khoo
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy*; D003680:Deglutition Disorders / Q000145:classification / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D015994:Incidence; D007830:Larynx / Q000528:radiation effects*; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk / Q000528:radiation effects; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods; D013280:Stomatitis / Q000150:complications