Clinical application of high-dose, image-guided intensity-modulated radiotherapy in high-risk prostate cancer.
OBJECTIVE
To 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
A 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.


RESULTS
A 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.


CONCLUSIONS
These results suggest that dose escalation to the PLN+P+SV using IMRT is feasible, with acceptable rates of acute toxicity.
Bayley
Andrew
A
Radiation Medicine Program, Princess Margaret Hospital, Toronto, ON, Canada. Andrew.Bayley@rmp.uhn.on.ca
Rosewall
Tara
T
Craig
Tim
T
Bristow
Rob
R
Chung
Peter
P
Gospodarowicz
Mary
M
Ménard
Cynthia
C
Milosevic
Michael
M
Warde
Padraig
P
Catton
Charles
C
D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D000368:Aged; D000369:Aged, 80 and over; D000726:Androgen Antagonists / Q000627:therapeutic use; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use; D005240:Feasibility Studies; D006801:Humans; D015182:Lymphatic Irradiation / Q000009:adverse effects / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010388:Pelvis; D011446:Prospective Studies; D011467:Prostate / Q000000981:diagnostic imaging / Q000473:pathology; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000150:complications; D011859:Radiography; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D012669:Seminal Vesicles / Q000000981:diagnostic imaging / Q000473:pathology / Q000528:radiation effects; D014555:Urination Disorders / Q000209:etiology
D000726:Androgen Antagonists; D018931:Antineoplastic Agents, Hormonal