• Andrew Bayley, Tara Rosewall, Tim Craig, Rob Bristow, Peter Chung, Mary Gospodarowicz, Cynthia Ménard, Michael Milosevic, Padraig Warde, and Charles Catton.
• Radiation Medicine Program, Princess Margaret Hospital, Toronto, ON, Canada. Andrew.Bayley@rmp.uhn.on.ca
• Int. J. Radiat. Oncol. Biol. Phys. 2010 Jun 1; 77 (2): 477-83.

PurposeTo report the feasibility and early toxicity of dose-escalated image-guided IMRT to the pelvic lymph nodes (LN), prostate (P), and seminal vesicles (SV).Methods And MaterialsA total of 103 high-risk prostate cancer patients received two-phase, dose-escalated, image-guided IMRT with 3 years of androgen deprivation therapy. Clinical target volumes (CTVs) were delineated using computed tomography/magnetic resonance co-registration and included the prostate, portions of the SV, and the LN. Planning target volume margins (PTV) used were as follows: P (10 mm, 7 mm posteriorly), SV (10 mm), and LN (5 mm). Organs at risk (OaR) were the rectal and bladder walls, femoral heads, and large and small bowel. The IMRT was planned with an intended dose of 55.1 Gy in 29 fractions to all CTVs (Phase 1), with P+SV consecutive boost of 24.7 Gy in 13 fractions. Daily online image guidance was performed using bony landmarks and intraprostatic markers. Feasibility criteria included delivery of intended doses in 80% of patients, 95% of CTV displacements incorporated within PTV during Phase 1, and acute toxicity rate comparable to that of lower-dose pelvic techniques.ResultsA total of 91 patients (88%) received the total prescription dose. All patients received at least 72 Gy. In Phase 1, 63 patients (61%) received the intended 55.1 Gy, whereas 87% of patients received at least 50 Gy. Dose reductions were caused by small bowel and rectal wall constraints. All CTVs received the planned dose in >95% of treatment fractions. There were no Radiation Therapy Oncology Group acute toxicities greater than Grade 3, although there were five incidences equivalent to Grade 3 within a median follow-up of 23 months.ConclusionThese results suggest that dose escalation to the PLN+P+SV using IMRT is feasible, with acceptable rates of acute toxicity.Copyright 2010 Elsevier Inc. All rights reserved.

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