title: A prognostic volumetric threshold of gross tumor volume in head and neck cancer patients treated with radiotherapy.
abstract: OBJECTIVE
  To determine the prognostic utility of a volumetric threshold for gross tumor volume (GTV) of the primary and nodal disease when accounting for the TNM classification in head and neck cancer (HNC) patients treated with definitive radiotherapy (RT).
  
  
  METHODS
  From 2004 to 2011, 79 HNC patients were treated to a median dose of 70 Gy, using intensity-modulated RT in 78.5% and 3-dimensional conformal RT in 21.5% with 83.5% receiving concurrent chemotherapy. Primary (GTV-P) and nodal (GTV-N) GTVs were derived from computed tomography (CT)-based contours for RT planning, of which 89.7% were aided by positron emission tomography-computed tomography. Local (LC), nodal (NC), distant (DC) control, and overall survival (OS) were assessed using the Kaplan-Meier product-limit method.
  
  
  RESULTS
  With a median follow-up of 27.1 months GTV-P, threshold of <32.9 mL (mean value) compared with ≥32.9 mL, correlated with improved 2-year LC (96.2% vs. 63.9%, P<0.0001), NC (100% vs. 69.2%, P<0.0001), DC (87.9% vs. 64.2%, P=0.001), and OS (88.4% vs. 58.6%, P=0.001). GTV-P demonstrated its prognostic utility in multivariate analyses when adjusted for tumor category, cancer site, and chemotherapy regimen. Nodal GTV (mean, 34.0 mL) was not predictive of nodal control and survival.
  
  
  CONCLUSIONS
  A volumetric threshold of the primary tumor may be used as an independent prognostic factor in patients with HNC undergoing definitive RT.
authors.affiliation: Departments of *Radiation Oncology †Radiology ‡Otolaryngology, Boston Medical Center, Boston University School of Medicine, Boston, MA.
authors.forename: Paul B
authors.initials: PB
authors.lastname: Romesser
authors.forename: Muhammad M
authors.initials: MM
authors.lastname: Qureshi
authors.forename: Rathan M
authors.initials: RM
authors.lastname: Subramaniam
authors.forename: Osamu
authors.initials: O
authors.lastname: Sakai
authors.forename: Scharukh
authors.initials: S
authors.lastname: Jalisi
authors.forename: Minh T
authors.initials: MT
authors.lastname: Truong
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006258:Head and Neck Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D020266:Radiotherapy, Conformal / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D047368:Tumor Burden / Q000528:radiation effects