The effect of pelvic irradiation on ileal function

Thirty-three patients with gynecological neoplasms undergoing radiotherapy to the pelvis had cholyl[1-14C]glycine breath tests to assess ileal function. Breath tests were performed on each patient in the first and fifth weeks of treatment and 19 of the patients had a third test three months post-treatment. In the first test, 29.9+/-16.8% (mean+/-SD) of the administered dose was excreted in breath 14C in 24 hours. This rose to 47.3+/-15.9% (t=6.08; p less than .001) in the fifth week and fell to 36.6+/-16% (t=2.29; p less than .05) at three months post-treatment. Eight patients had breath tests performed one year post-treatment and the test percentages were 32.7+/-7.8% (t=1.19; p less than .10). The increase in 14CO2 excretion in the fifth week of treatment occurred at a time when most patients were having diarrhea. The data suggest that bile acid malabsorption due to ileal dysfunction may be a factor in radiation-induced diarrhea which occurs in nearly all patients during pelvic irradiation.