title: Reduced acute toxicity associated with the use of volumetric modulated arc therapy for the treatment of adenocarcinoma of the prostate.
abstract: OBJECTIVE
  Novel techniques to deliver intensity modulated radiation therapy (IMRT) have resulted in improved treatment efficiency and dosimetric endpoints. We aimed to compare acute gastrointestinal (GI) and genitourinary (GU) toxicity in patients treated for adenocarcinoma of the prostate (ACP) using volumetric modulated arc therapy (VMAT).
  
  
  METHODS
  A total of 122 (71 IMRT and 51 VMAT) ACP patients treated from 2004 to 2011 with definitive external beam radiation therapy were analyzed. Dose-volume histogram endpoints (V40, V65, V70, and V75 of the bladder and rectum) were collected for each patient. Median follow-up for patients treated with VMAT was 269 days versus IMRT was 1121 days. Acute Common Toxicity Criteria for Adverse Events (CTCAE) GI and GU toxicity scores, obtained during each weekly treatment check, were compared across cohorts. The univariate (UV) association between the covariates and outcomes was assessed and multivariable (MV) cumulative logit models were fit for each outcome.
  
  
  RESULTS
  Median patient age was 68 years and median prostate-specific antigen was 8.3. Both bladder and rectal V40, V65, V70, and V75 were all higher in the IMRT group versus the VMAT group (P < .05), which was likely influenced by larger planning target volumes in the IMRT group. The VMAT group had significantly lower rates of acute GU and acute GI CTCAE toxicity on UV association analysis. On MV analysis, VMAT remained independently associated with acute GU (odds ratio [OR], 0.18; 95% confidence interval [CI], 0.07-0.44; P < .001) and GI (OR, 0.16; 95% CI, 0.07-0.41; P < .001) toxicity.
  
  
  CONCLUSIONS
  VMAT appears to be independently associated with lower rates of acute GI and GU toxicity when compared with traditional IMRT. Further exploration of toxicity improvements associated with VMAT use in the definitive treatment of ACP is needed.
authors.affiliation: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia. Electronic address: whall4@emory.edu.
authors.forename: William A
authors.initials: WA
authors.lastname: Hall
authors.affiliation: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Lauren
authors.initials: L
authors.lastname: Colbert
authors.affiliation: Biostatistics & Bioinformatics Shared Resource at Winship Cancer Institute, Atlanta, Georgia.
authors.forename: Dana
authors.initials: D
authors.lastname: Nickleach
authors.affiliation: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Joseph
authors.initials: J
authors.lastname: Shelton
authors.affiliation: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: David M
authors.initials: DM
authors.lastname: Marcus
authors.affiliation: Biostatistics & Bioinformatics Shared Resource at Winship Cancer Institute, Atlanta, Georgia.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Switchenko
authors.affiliation: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Rossi
authors.affiliation: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Karen
authors.initials: K
authors.lastname: Godette
authors.affiliation: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Sherrie
authors.initials: S
authors.lastname: Cooper
authors.affiliation: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Ashesh B
authors.initials: AB
authors.lastname: Jani