title: Adaptive radiation therapy for breast IMRT-simultaneously integrated boost: three-year clinical experience.
abstract: OBJECTIVE
  It has been shown that seroma volumes decrease during breast conserving radiotherapy in a significant percentage of patients. We report on our experience with an adaptive radiation therapy (ART) strategy involving rescanning and replanning patients to take this reduction into account during a course of intensity-modulated radiation therapy with simultaneously integrated boost (IMRT-SIB).
  
  
  METHODS
  From April 2007 till December 2009, 1274 patients eligible for SIB treatment were enrolled into this protocol. Patients for which the time between the initial planning CT (CT(1)) and lumpectomy was less than 30 days and who had an initial seroma volume >30 cm(3) were rescanned at day 10 of treatment (CT(2)) and replanned when significant changes were observed by the radiation oncologist. Patients received 28 fractions of 1.81 Gy to the breast and 2.30 Gy to the boost volume.
  
  
  RESULTS
  Nine percent (n=113) of the 1274 patients enrolled met the criteria and were rescanned. Of this group, 77% (n=87) of treatment plans were adapted. Time between surgery and CT(1) (20 days versus 20 days for adapted and non-adapted plans, p=0.89) and time between CT(1) and CT(2) (21 days versus 22 days for adapted and non-adapted plans, p=0.43) revealed no procedural differences which might have biased our results. In the adapted plans, seroma decreased significantly from 60 to 27 cm(3) (p<0.001), TBV from 70 to 45 cm(3) (p<0.001) and PTV(boost) from 277 to 220 cm(3) (p<0.001). The volume receiving more than 95% of the boost dose (V(95%(total-dose))) could be reduced by 19% (linear fit, R(2)=0.73) from on average 360 to 292 cm(3) (p<0.001). Delay in treatment and the use of a prolonged treatment schedule with different fractionation for patients with seroma could thus be prevented.
  
  
  CONCLUSIONS
  The adaptive radiation therapy IMRT-SIB procedure has proven to be efficient and effective, leading to a clinically significant reduction of the high dose volume. Seroma present in a subgroup of patients referred for breast radiation therapy does not hamper the introduction of highly conformal IMRT-SIB techniques.
authors.affiliation: Department of Radiation Oncology, Catharina Hospital, Eindhoven, The Netherlands. coen.hurkmans@cze.nl
authors.forename: Coen W
authors.initials: CW
authors.lastname: Hurkmans
authors.forename: Ingrid
authors.initials: I
authors.lastname: Dijckmans
authors.forename: Miranda
authors.initials: M
authors.lastname: Reijnen
authors.forename: Jorien
authors.initials: J
authors.lastname: van der Leer
authors.forename: Corine
authors.initials: C
authors.lastname: van Vliet-Vroegindeweij
authors.forename: Maurice
authors.initials: M
authors.lastname: van der Sangen
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D061089:Radiotherapy, Image-Guided; D050397:Radiotherapy, Intensity-Modulated; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden