Clinical experience with intensity modulated radiation therapy (IMRT) in prostate cancer.
OBJECTIVE
To compare acute and late toxicities of high-dose radiation for prostate cancer delivered by either conventional three-dimensional conformal radiation therapy (3D-CRT) or intensity modulated radiation therapy (IMRT).


METHODS
Between September 1992 and February 1998, 61 patients with clinical stage T1c- T3 prostate cancer were treated with 3D-CRT and 171 with IMRT to a prescribed dose of 81 Gy. To quantitatively evaluate the differences between conventional 3D-CRT and IMRT, 20 randomly selected patients were planned concomitantly by both techniques and the resulting treatment plans were compared. Acute and late radiation-induced morbidity was evaluated in all patients and graded according to the Radiation Therapy Oncology Group toxicity scale.


RESULTS
Compared with conventional 3D-CRT, IMRT improved the coverage of the clinical target volume (CTV) by the prescription dose and reduced the volumes of the rectal and bladder walls carried to high dose levels (P<0.01), indicating improved conformality with IMRT. Acute and late urinary toxicities were not significantly different for the two methods. However, the combined rates of acute grade 1 and 2 rectal toxicities and the risk of late grade 2 rectal bleeding were significantly lower in the IMRT patients. The 2-year actuarial risk of grade 2 bleeding was 2% for IMRT and 10% for conventional 3D-CRT (P<0.001).


CONCLUSIONS
The data demonstrate the feasibility and safety of high-dose IMRT for patients with localized prostate cancer and provide a proof-of-principle that this method improves dose conformality relative to tumor coverage and exposure to normal tissues.
Zelefsky
M J
MJ
Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, 1275 York Ave., New York, NY 10021, USA.
Fuks
Z
Z
Happersett
L
L
Lee
H J
HJ
Ling
C C
CC
Burman
C M
CM
Hunt
M
M
Wolfe
T
T
Venkatraman
E S
ES
Jackson
A
A
Skwarchuk
M
M
Leibel
S A
SA
D000368:Aged; D000369:Aged, 80 and over; D005240:Feasibility Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000379:methods* / Q000592:standards; D012449:Safety