Acute Toxicity Results Using Dynamic Intensity Modulated Radiotherapy dIMRT in HighRisk Prostate Ade

1
Acute Toxicity Results Using Dynamic Intensity
Modulated Radiotherapy (dIMRT) in High-Risk
Prostate Adenocarcinoma N. Pervez, R. Pearcey,
M. Parliament, A. Mihai, D. Yee, J. Amanie, A.
Murtha, K. Wachowicz, C. Field, M. Mackenzie, G.
Fallone. Cross Cancer Institute/University of
Alberta, Edmonton, Alberta, Canada.

• Objectives
• Primary objective to determine the rate of
  acute and late rectal toxicity.
• Secondary objectives biochemical control,
  overall and disease free survival rates
• Background
• The a/ß ratio for prostate is lower than for the
  rectum. Therefore, hypo-fractionation may deliver
  higher biological doses to the prostate and it is
  expected to improve the therapeutic ratio (TR)
• Methods and Materials
• Phase-II study 60 eligible patients
• Eligibility criteria
• Clinical stage T3 or T4 and/or Gleason Score
  8-10 and/or PSA gt20ng/L
• Gleason score 7 with PSA gt15ng/L
• Anti androgen therapy was prescribed for total
  duration of 2-3 years
• Planning
• CT simulation and 3T-MRI in treatment position.
• Targets and OAR delineation using Eclipse Varian
  version 7.4 on CT-MR registered image (see
  table 1)
• A single-phase treatment plan (Helical
  Tomotherapy Hi-Art system) 68 Gy to 95 of the
  PTV68 and 45 Gy to 95 of the PTV 45 in 25
  daily fractions, over five weeks (table 2)
• RT was delivered using helical tomotherapy
• Acute and late toxicity were recorded as per
  RTOG criteria.

• Results
• Figures 3-5 present typical dose distribution for
  helical tomotherapy
• CT and MRI image fusion improved conformal target
  delineation (table 3)
• Mean dose to PTV 68 69.09 Gy
• Mean dose to PTV45 49.53 Gy
• OAR dose constraints were achieved in all
  patients (table 3)
• Mean doses to rectum 47.1Gy
• Mean dose bladder 50Gy
• Mean dose femora 17.6 Gy respectively

Fig. 8 GI toxicity during RT
Fig. 7 GU toxicity during RT
Percentage of patients
Percentage of patients
Fig.3 Tomotherapy plan single axial image
Fig.4 Tomotherapy plan single coronal image
Time of assessment
Time of assessment
Fig.1 Non-contrast planning pelvic scan
(AcQ-Sim)
Fig.2 Non-contrast 3-T MRI pelvic scan
Fig. 10 GI toxicity after RT
Fig. 9 GU toxicity after RT
Percentage of patients
Percentage of patients
Fig.5 Typical Tomotherapy planning DVHs
Fig.6 Helical Tomotherapy unit
Table 1 Targets and OAR delineation
Time of assessment
Time of assessment
Table 3 Average dose to targets and OAR
Note G Grade and W Week

• Conclusions
• CT-MRI image fusion may improve target
  delineation in prostate cancer patients
• Helical tomotherapy can safely deliver higher
  biological doses using hypo-fractionated dynamic
  intensity modulated radiotherapy
• Acute toxicity appears to be acceptable using
  this regimen
• Further assessment of this hypo-fractionated
  regimen will require longer follow-up

• Acute toxicity
• analyzed in up to 60 patients so far (table 4,
  figures 6-10)
• No Grade 4 or 5 acute toxicity

Table 2 Treatment goals and OAR constraints
Table 4 Acute genito-urinary and lower
gastro-intestinal toxicities in patients
undergoing hypo-fractionated dynamic IMRT

• Acknowledgements
• This study was sponsored by Bridge and Pilot,
  Alberta Cancer Board funding.
• Juliette Jordan (Data Manager) and Michelle
  Encarnacao (Clinical Research Nurse)