Dosimetry and preliminary acute toxicity in the first 100 men treated for prostate cancer on a randomized hypofractionation dose escalation trial.
OBJECTIVE
The alpha/beta ratio for prostate cancer is postulated to be between 1 and 3, giving rise to the hypothesis that there may be a therapeutic advantage to hypofractionation. The dosimetry and acute toxicity are described in the first 100 men enrolled in a randomized trial.


METHODS
The trial compares 76 Gy in 38 fractions (Arm I) to 70.2 Gy in 26 fractions (Arm II) using intensity modulated radiotherapy. The planning target volume (PTV) margins in Arms I and II were 5 mm and 3 mm posteriorly and 8 mm and 7 mm in all other dimensions. The PTV D95% was at least the prescription dose.


RESULTS
The mean PTV doses for Arms I and II were 81.1 and 73.8 Gy. There were no differences in overall maximum acute gastrointestinal (GI) or genitourinary (GU) toxicity acutely. However, there was a slight but significant increase in Arm II GI toxicity during Weeks 2, 3, and 4. In multivariate analyses, only the combined rectal DVH parameter of V65 Gy/V50 Gy was significant for GI toxicity and the bladder volume for GU toxicity.


CONCLUSIONS
Hypofractionation at 2.7 Gy per fraction to 70.2 Gy was well tolerated acutely using the planning conditions described.
Pollack
Alan
A
Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA. Alan.Pollack@FCCC.edu
Hanlon
Alexandra L
AL
Horwitz
Eric M
EM
Feigenberg
Steven J
SJ
Konski
Andre A
AA
Movsas
Benjamin
B
Greenberg
Richard E
RE
Uzzo
Robert G
RG
Ma
C-M Charlie
CM
McNeeley
Shawn W
SW
Buyyounouski
Mark K
MK
Price
Robert A
RA
D019583:Dose Fractionation, Radiation; D041981:Gastrointestinal Tract / Q000528:radiation effects; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D012007:Rectum / Q000528:radiation effects; D012306:Risk; D047368:Tumor Burden; D001743:Urinary Bladder / Q000528:radiation effects