To determine the short-term and long-term toxicity of abdominal and pelvic radiation therapy in a cohort of patients with inflammatory bowel disease (IBD). We hypothesize that with newer techniques, such as intensity-modulated radiation therapy (IMRT) and 3-dimensional conformal radiotherapy (3D-CRT), patients with IBD can safely undergo abdominal and pelvic radiation, with low risk for major acute or late toxicity.

Nineteen consecutive patients with IBD (14 with ulcerative colitis, 5 with Crohn disease) who were treated with abdominal or pelvic external beam radiation therapy at Stanford University from 1997 to 2011 were identified. Fourteen patients were treated with IMRT and 5 were treated with 3D-CRT. Treated sites included prostate (n=8), gastric/esophageal (n=5), rectal/anal (n=3), and liver (n=3) tumors. Charts were reviewed and toxicity was graded according to the Common Terminology Criteria for Acute Events version 4.0. Median follow-up was 32.5 months. Fisher exact test was used to determine if any clinical and/or treatment factors were associated with toxicity outcomes.

Acute grade ≥3 toxicity occurred in 2 patients (11%). Late grade ≥3 toxicity occurred in 1 patient (6%). Acute grade ≥2 toxicity occurred in 28% of patients treated with IMRT versus 100% of patients treated with 3D-CRT (P=0.01). Acute grade ≥2 gastrointestinal toxicity was lower in patients treated with IMRT versus 3D-CRT (14% vs. 100%, respectively, P=0.002). Late grade ≥2 toxicity occurred in 21% of patients. Higher total dose (Gy) and biologically effective dose (Gy) were associated with increased rates of late grade ≥2 toxicity (P=0.02 and 0.03, respectively).

These data suggest that select patients with IBD can safely undergo abdominal and pelvic radiation therapy. The use of IMRT was associated with decreased acute toxicity. Acute and late severe toxicity rates were low in this patient population with the use of modern radiation techniques.