Gastrointestinal toxicity and its relation to dose distributions in the anorectal region of prostate cancer patients treated with radiotherapy.
OBJECTIVE
To study the correlations between the dose distributions in the anorectal region and late GI symptoms in patients treated for localized prostate carcinoma.


METHODS
Data from a randomized study were analyzed. In this trial, patients were treated with either rectangular or conformal fields with a dose of 66 Gy. Data concerning GI symptoms were collected from questionnaires of 197 patients. The distributions of the anorectal region were projected on maps, and the dose parameters were calculated. The incidences of complaints were studied as a function of the dose-area parameters and clinical parameters, using a proportional hazard regression model. Finally, we tested a series of dose parameters originating from different parts of the anorectal region.


RESULTS
Analyzing the total region, only a statistically significant dose-area effect relation for bleeding was found (p < 0.01). Defining subareas, we found effect relations for bleeding, soiling, fecal incontinence, and mucus loss. For bleeding and mucus loss, the strongest correlation was found for the dose received by the upper 70-80% of the anorectal region (p < 0.01). For soiling and fecal incontinence, we found the strongest association with the dose to the lower 40-50% (p < 0.05).


CONCLUSIONS
We found evidence that complaints originate from specific regions of the irradiated lower GI tract. Bleeding and mucus loss are probably related to irradiation of the upper part of the rectum. Soiling and fecal incontinence are more likely related to the dose to the anal canal and the lower part of the rectum.
Heemsbergen
Wilma D
WD
Department of Radiotherapy, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands. wheems@nki.nl
Hoogeman
Mischa S
MS
Hart
Guus A M
GA
Lebesque
Joos V
JV
Koper
Peter C M
PC
D000704:Analysis of Variance; D003085:Colic / Q000209:etiology; D003672:Defecation / Q000528:radiation effects; D003967:Diarrhea / Q000209:etiology; D004307:Dose-Response Relationship, Radiation; D005242:Fecal Incontinence / Q000209:etiology; D005767:Gastrointestinal Diseases / Q000209:etiology*; D006471:Gastrointestinal Hemorrhage / Q000209:etiology; D006801:Humans; D008297:Male; D016016:Proportional Hazards Models; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000150:complications*; D012007:Rectum / Q000528:radiation effects