title: Volumetric stratification of cT4 stage head and neck cancer.
abstract: BACKGROUND
  Locoregionally advanced stage head and neck cancer (HNC) is known for unfavorable outcome with only ~ 40-50% 3-year overall survival (OS). Clinical T4 stage includes a wide range of tumor burden. The lack of further nonsurgical subgrouping of cT4 stage makes intercenter outcome of irradiated cohorts difficult. Aim of this analysis was to further stratify cT4 stage HNC using volumetric staging.
  
  
  METHODS
  Between January 2002 and January 2013, a total of 201 cT4 stage squamous cell cancer (SCC) HNC patients referred to our center for curative definitive radiation were consecutively irradiated. Radiation was performed using modulated techniques. Total gross tumor volumes (tGTV: primary+nodal tumor volume) of all patients have retrospectively been stratified using a prospectively evaluated volumetric staging system which bases on 3 cut-offs (15/70/130 ml), translating into 4 prognostic subgroups [V1: 1-15 ml (n=15), V2: 16-70 ml (108), V3: 71-130 ml (62), V4: >130 ml (16)]. OS, disease-free survival (DFS), locoregional control (LRC), and distant metastasis-free survival (DMFS) rates were calculated.
  
  
  RESULTS
  The mean/median follow-up was 31/23 months (range 1-116 months). The 3-year OS, DFS, LRC, and DMFS rates of the entire cohort were 63, 44, 48, and 77%, respectively. Volumetric staging revealed its potential to prognostically statistically significantly divide the cT4 cohort into 4 volume subgroups (V1/2/3/4): OS: 90%/72%/58%/18%; DFS: 83%/50%/39%/10%; LRC: 81%/53%/47%/15%; DMFS: 93%/90%/70%/41%, all p<0.0001.
  
  
  CONCLUSIONS
  Volumetric staging allowed a highly statistically significant stratification of cT4 HNC stages into prognostic subgroups, which offers the chance of better intercenter comparability of irradiated advanced stage HNC cohorts.
authors.affiliation: Department of Radiation Oncology, University Hospital Zurich, Raemistr. 100, 8091, Zurich, Switzerland, gabriela.studer@usz.ch.
authors.forename: G
authors.initials: G
authors.lastname: Studer
authors.forename: C
authors.initials: C
authors.lastname: Glanzmann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000401:mortality* / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D006258:Head and Neck Neoplasms / Q000401:mortality* / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D020266:Radiotherapy, Conformal / Q000401:mortality*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D000077195:Squamous Cell Carcinoma of Head and Neck; D015996:Survival Rate; D013557:Switzerland / Q000453:epidemiology; D016896:Treatment Outcome; D047368:Tumor Burden