Clinical and dosimetric predictors of late rectal toxicity after conformal radiation for localized prostate cancer: results of a large multicenter observational study.
OBJECTIVE
Assessing the predictors of late rectal toxicity after high-dose conformal radiotherapy for prostate cancer.


METHODS
One thousand one hundred thirty-two patients entered a prospective observational multicentric study; late rectal toxicity was evaluated by a self-reported questionnaire. Results concerning bleeding and faecal incontinence of 718/1132 patients with a complete follow-up at 36 months were analysed. The correlation between a number of clinical-dosimetric parameters and moderate/severe toxicity was investigated by univariate and multivariate logistic analyses.


RESULTS
Fifty-two (7.2%) and 57/718 (7.9%) patients were scored as moderate/severe bleeders and faecal incontinents, respectively; 19/57 incontinent patients showed persistent incontinence at 36 months. Bleeding was mainly correlated with V75 Gy while severe bleeding was mainly correlated with the previous abdominal/pelvic surgery; a different rectal dose-volume relationship in the two groups of patients (with/without surgery) was found. Moderate/severe acute toxicity was weakly correlated to late bleeding. The best predictor of faecal incontinence was acute toxicity (OR=4 and 7 for chronic and actuarial incontinence, respectively).


CONCLUSIONS
The application of rectal dose-volume constraints limited the incidence of rectal bleeding. The risk of bleeding may be further reduced by limiting V75 Gy<5% and, in the case of patients previously submitted to abdominal/pelvic surgery, V70 Gy<15-20%. Faecal incontinence seems to be mainly a consequential effect after acute toxicity.
Fellin
Gianni
G
Radiotherapy and Medical Physics, Ospedale Santa Chiara, Trento, Italy.
Fiorino
Claudio
C
Rancati
Tiziana
T
Vavassori
Vittorio
V
Baccolini
Micaela
M
Bianchi
Carla
C
Cagna
Emanuela
E
Gabriele
Pietro
P
Mauro
Floranna
F
Menegotti
Loris
L
Monti
Angelo Filippo
AF
Stasi
Michele
M
Valdagni
Riccardo
R
D005242:Fecal Incontinence / Q000209:etiology; D006471:Gastrointestinal Hemorrhage / Q000209:etiology; D006801:Humans; D016015:Logistic Models; D008297:Male; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects*; D012007:Rectum / Q000528:radiation effects*