title: Metabolic tumor volume predicts disease progression and survival in patients with squamous cell carcinoma of the anal canal.
abstract: PET imaging has become a useful diagnostic tool in patients with anal cancer. We evaluated the prognostic value of metabolic tumor volume (MTV) in patients with anal cancer treated with definitive chemoradiotherapy.
  
  
  METHODS
  Patients with anal cancer who underwent PET imaging for pretreatment staging or radiation therapy planning from 2003 to 2011 were included. PET parameters included MTV and maximum standardized uptake value (SUVmax). Total MTV (MTV-T) was defined as the sum of the volumes above a standardized uptake value 50% of the SUVmax within the primary tumor and involved nodes. Kaplan-Meier and Cox regression models were used to test for associations between metabolic or clinical endpoints and overall survival (OS), progression-free survival (PFS), and event-free survival (EFS).
  
  
  RESULTS
  Thirty-nine patients were included. Median follow-up for the cohort was 22 mo. Overall, 6 patients died and 9 patients had disease progression. The 2-y OS, PFS, and EFS for the entire cohort were 88%, 74%, and 69%, respectively. Higher MTV-T was associated with worse OS (P = 0.04), PFS (P = 0.004), and EFS (P = 0.002) on univariate analysis. Patients with an MTV greater than 26 cm(3) had worse PFS than did those with an MTV of 26 cm(3) or less (33% vs. 82%, P = 0.003). SUVmax was not prognostic for any outcome. Higher T classification (T3/T4 vs. T1/T2) was associated with worse PFS and EFS. When adjusting for T classification, MTV-T remained a significant predictor for PFS (P = 0.01) and EFS (P = 0.02).
  
  
  CONCLUSIONS
  MTV-T yields prognostic information on PFS and EFS beyond that of established prognostic factors in patients with anal cancer.
authors.affiliation: Department of Radiation Oncology, Stanford University, Stanford, California 94305-5847, USA.
authors.forename: Jose G
authors.initials: JG
authors.lastname: Bazan
authors.forename: Albert C
authors.initials: AC
authors.lastname: Koong
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Kapp
authors.forename: Andrew
authors.initials: A
authors.lastname: Quon
authors.forename: Edward E
authors.initials: EE
authors.lastname: Graves
authors.forename: Billy W
authors.initials: BW
authors.lastname: Loo
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Chang
mesh_terms: D000704:Analysis of Variance; D001005:Anus Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology* / Q000628:therapy; D001692:Biological Transport; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology* / Q000628:therapy; D059248:Chemoradiotherapy; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D049268:Positron-Emission Tomography; D016019:Survival Analysis; D047368:Tumor Burden