Acute morbidity related to treatment volume during 3D-conformal radiation therapy for prostate cancer.
OBJECTIVE
To investigate the relation between acute toxicity and irradiated volume in the organs at risk during three-dimensional conformal radiation therapy for prostate cancer.


METHODS
From January to December 2001, we treated 132 prostate cancer patients to a prescribed target dose of 70 Gy. Twenty-six patients (20%) received irradiation to the prostate only (Group P), 86 patients (65%) had field arrangements encompassing the prostate and seminal vesicles (Group PSV) while 20 (15%) received modified pelvic fields (Group MPF). A four-field conformal box technique was used. Acute toxicity according to the RTOG scoring system was prospectively recorded throughout the course of treatment.


RESULTS
Overall, radiation was well tolerated with 11%, 16% and 35% Grade 2 gastro-intestinal (GI) toxicity and 19%, 34% and 35% Grade 2 or higher genito-urinary (GU) toxicity in Groups P, PSV and MPF, respectively. In univariate and multivariate analyses treatment group was a significant predictor for Grade 2 or higher acute morbidity. In multivariate logistic regression, the rectum dose-volume histogram parameters were correlated to the incidence of acute Grade 2 GI toxicity, with the fractional volumes receiving more than 37-40 Gy and above 70 Gy showing the statistically strongest correlation. The fractional bladder volume receiving more than 14-27 Gy showed the statistically strongest correlation with acute GU toxicity.


CONCLUSIONS
3D-CRT radiation therapy to 70 Gy for prostate cancer was well tolerated. Only two of the 132 patients in the cohort experienced acute bladder toxicity Grade 3, none had Grade 3 rectal toxicity. Uni- and multivariate analyses indicated that the volume treated was a significant factor for the incidence of Grade 2 or higher acute morbidity.
Karlsdóttir
Asa
A
Section of Oncology, Institute of Medicine, Haukeland University Hospital, University of Bergen, N-5021 Bergen, Norway.
Johannessen
Dag C
DC
Muren
Ludvig Paul
LP
Wentzel-Larsen
Tore
T
Dahl
Olav
O
D000208:Acute Disease; D000368:Aged; D005767:Gastrointestinal Diseases / Q000209:etiology*; D006801:Humans; D008297:Male; D052801:Male Urogenital Diseases / Q000209:etiology*; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects*