Absolute volume of the rectum and AUC from rectal DVH between 25Gy and 50Gy predict acute gastrointestinal toxicity with IG-IMRT in prostate cancer.
BACKGROUND
To determine whether dose/volume specific endpoints (DVSE) or Area under the rectal DVH curve (rAUC) better predict acute gastrointestinal (GI) toxicity in prostate cancer patients treated with IMRT in the era of daily image guidance (IG-IMRT).


METHODS
A set of DVSE was recorded from V25 to V75 (increments of 5Gy) (both in % and in cc) for 180 men. The rAUC was calculated for doses ranging between 25Gy and 50Gy (rAUC25-50). Univariate and multivariate logistic regressions were performed to determine the relationship between DVSE or rAUC25-50and the appearance of any acute GI toxicity.


RESULTS
The rates of acute grade 1 (G1), G2 and G3 GI toxicities were 53.3 %, 10.6 % and 1.1 %, respectively. No G4+ toxicity was observed. Rectal V25 to V75 expressed in % were not predictive of G ≥ 1 GI toxicity (p ≥ 0.12) whereas rectal V25 to V50 expressed in cc did correlate with GI toxicity G ≥ 1 (p ≤ 0.04). rAUC25-50expressed in cc. Gy correlated significantly with the occurrence of any acute GI toxicity G ≥ 1 (p = 0.027).


CONCLUSIONS
The absolute volume of the rectum between 25Gy and 50Gy and rAUC25-50could significantly predict any acute rectal toxicity in prostate cancer patients treated with daily IG-IMRT.
Department of Radiation Oncology, Centre Georges Francois Leclerc, 1, rue du Pr Marion, 21049, Dijon, France. cmirjolet@cgfl.fr.
Céline
C
Mirjolet
Medical Imaging Group, Laboratory of Electronics, Computer Science and Imaging, (Le2I), CNRS 6306, University of Burgundy, 21000, Dijon, France.
Paul M
PM
Walker
Department of Biostatistics, Centre Georges Francois Leclerc, 21049, Dijon, France.
Mélanie
M
Gauthier
Department of Biostatistics, Centre Georges Francois Leclerc, 21049, Dijon, France.
Cécile
C
Dalban
Department of Radiation Oncology, Centre Georges Francois Leclerc, 1, rue du Pr Marion, 21049, Dijon, France.
Suzanne
S
Naudy
Department of Radiation Oncology, Centre Georges Francois Leclerc, 1, rue du Pr Marion, 21049, Dijon, France.
Frédéric
F
Mazoyer
Department of Radiation Oncology, Centre Georges Francois Leclerc, 1, rue du Pr Marion, 21049, Dijon, France.
Etienne
E
Martin
Department of Radiation Oncology, Centre Georges Francois Leclerc, 1, rue du Pr Marion, 21049, Dijon, France.
Philippe
P
Maingon
Department of Radiation Oncology, Centre Georges Francois Leclerc, 1, rue du Pr Marion, 21049, Dijon, France.|Medical Imaging Group, Laboratory of Electronics, Computer Science and Imaging, (Le2I), CNRS 6306, University of Burgundy, 21000, Dijon, France.
Gilles
G
Créhange
D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D012007:Rectum / Q000528:radiation effects*
Acute rectal toxicity predictive factor; Prostate cancer; Radiotherapy