Radiology, Vol 195, 699-703, Copyright © 1995 by Radiological Society of North America
Proctitis after conventional external radiation therapy for prostate cancer: importance of minimizing posterior rectal dose
KH Cho, CK Lee and SH Levitt
Department of Therapeutic Radiology-Radiation Oncology, University of Minnesota Hospital and Clinics, Minneapolis 55455, USA.
PURPOSE: To identify factors associated with the prevalence of radiation
proctitis in patients with prostate cancer treated with external radiation
therapy and to determine if a dose-response relationship exists. MATERIALS
AND METHODS: The study included 101 prostate cancer patients treated at the
University of Minnesota Hospital and Clinics between 1970 and 1987.
Radiation therapy at a daily dose of 175-200 cGy was given for 5
consecutive days per week for 7 weeks with a 10-24-MV linear accelerator.
Mean dose to the prostate was 6,795 cGy (range, 5,579-7,417 cGy).
Simulation radiographs obtained with rectal barium were analyzed in 51
patients. Doses were calculated at specific points in the boost field.
RESULTS: Radiation proctitis developed in 19 patients. No pretreatment or
treatment factors were associated with a higher prevalence of proctitis.
Statistically significant correlation (P < .042) was found between the
development of proctitis and dose to the posterior rectum. At chi 2
analysis, proctitis was statistically significantly (P < .005)
associated with posterior rectal doses of > 5,000 cGy. CONCLUSION: A
high posterior rectal dose (> 5,000 cGy) is associated with increased
prevalence of proctitis after radiation therapy.
