title: Hypofractionation with VMAT versus 3DCRT in post-operative patients with prostate cancer.
abstract: OBJECTIVE
  To retrospectively evaluate and compare the incidence of acute genitourinary (aGU), upper gastrointestinal (uGI) and rectal (lGI) injuries after radiotherapy with hypo-fractionation by volumetric modulation arc therapy (VMAT, the Hypo-RapidArc group) and conventional fractionation by three-dimensional conformal radiotherapy (3DCRT) in patients with localized prostate cancer treated, after radical prostatectomy, with prostatic bed irradiation.
  
  
  METHODS
  Between 2007 and 2012, 84 consecutive patients with clinically localized prostate cancer submitted to radical prostatectomy were also treated with irradiation to the prostate bed. Forty-five received 3DCRT and 39 Hypo-RapidArc. The median age was 67 and 69 years for 3DCRT and Hypo-RapidArc groups respectively. The median dose to the prostatic bed was 70 Gy in both groups: 2 Gy/fraction in the 3DCRT group and 2.5 Gy/fraction in the Hypo-RapidArc group. After radical prostatectomy, the median time-to-RT was 15 and 16 months respectively. Acute and late toxicities were scored according to the Radiation Therapy and Oncology Group/European Organization for Research and Treatment of Cancer system.
  
  
  RESULTS
  Grade 2aGU was recorded in 16% of cases in the 3DRCT group and in 10% in the Hypo-RapidArc group. No acute grade 2 upper gastrointestinal (uGI) toxicities were found in the 3DCRT versus 5% in the Hypo-RapidArc group. The incidence of grade 2 lower gastrointestinal (lGI) toxicities was 22% in the 3DCRT group versus 15% in the Hypo-RapidArc group. No grade 3 or greater toxicities were found in either group. In both groups, good planning target volume coverage was achieved: V95% was recorded as 96.3 ± 3.6% (mean ± standard deviation) and 95.7 ± 8.9 for the 3DRCT and the Hypo-RapidArc groups, respectively. The mean rectal volume dose receiving at least 70 Gy was 9.1 ± 10.8% and 0.1 ± 0.6% respectively. The mean dose to the bladder was 49.5 ± 12.3 Gy and 37.2 ± 5.2 Gy respectively. Significant correlation between late rectal toxicity and the maximum dose to the rectum, V70Gy, was found in the 3DCRT group, while no significant correlations were found for acute toxicity.
  
  
  CONCLUSIONS
  The results presented in this study demonstrate the feasibility of a moderate hypo-fractionation regimen with RapidArc in the postoperative setting. Longer-term data are needed to confirm late toxicity profiles.
authors.affiliation: Humanitas Cancer Center, Istituto Clinico Humanitas, Via Manzoni 56, 20089, Rozzano, Milano, Italy. filippo.alongi@humanitas.it.
authors.forename: Filippo
authors.initials: F
authors.lastname: Alongi
authors.forename: Luca
authors.initials: L
authors.lastname: Cozzi
authors.forename: Antonella
authors.initials: A
authors.lastname: Fogliata
authors.forename: Cristina
authors.initials: C
authors.lastname: Iftode
authors.forename: Tiziana
authors.initials: T
authors.lastname: Comito
authors.forename: Alessandro
authors.initials: A
authors.lastname: Clivio
authors.forename: Elisa
authors.initials: E
authors.lastname: Villa
authors.forename: Francesca
authors.initials: F
authors.lastname: Lobefalo
authors.forename: Piera
authors.initials: P
authors.lastname: Navarria
authors.forename: Giacomo
authors.initials: G
authors.lastname: Reggiori
authors.forename: Pietro
authors.initials: P
authors.lastname: Mancosu
authors.forename: Elena
authors.initials: E
authors.lastname: Clerici
authors.forename: Stefano
authors.initials: S
authors.lastname: Tomatis
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Taverna
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: Graziotti
authors.forename: Marta
authors.initials: M
authors.lastname: Scorsetti
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003131:Combined Modality Therapy; D019583:Dose Fractionation, Radiation; D005767:Gastrointestinal Diseases / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D012189:Retrospective Studies
keywords: Hypofractionation; RapidArc; VMAT; prostate cancer