Background and purpose: To determine whether treatment prone on a belly-board significantly reduces the volume of small bowel irradiated in women receiving adjuvant radiotherapy for gynecologic cancer, and to prospectively study acute small bowel toxicity using an accepted recording instrument.
Material and methods: Thirty-two gynecologic patients underwent simulation with CT scanning supine and prone. Small bowel was delineated on every CT slice, and treatment was prone on the belly-board using 3-5 fields-typically Anterior, Right and Left Lateral, plus or minus Lateral Boosts. Median prescribed dose was 50.4 Gy and all treatments were delivered in 1.8 Gy fractions. Concomitant Cisplatin was administered in 13 patients with cervical carcinoma. Comparison of small bowel dose-volumes was made between supine and prone, with each subject acting as their own matched pair. Acute small bowel toxicity was prospectively measured using the Common Toxicity Criteria: Version 2.0.
Results: Treatment prone on the belly-board significantly reduced the volume of small bowel receiving > or = 100; > or = 95; > or = 90; and > or = 80% of the prescribed dose, but not > or = 50%. This was found whether volume was defined in cubic centimeters or % of total small bowel volume. Of 29 evaluable subjects, 2 (7%) experienced 1 episode each of grade 3 diarrhoea. All other toxicity events were grade 2 or less and comprised diarrhoea (59%), abdominal pain or cramping (48%), nausea (38%), anorexia (17%), vomiting (10%). There were no Grade 4 events and no treatment days were lost due to toxicity.
Conclusions: Treatment prone on a belly-board device results in significant small bowel sparing, during adjuvant radiotherapy for gynecologic cancer. The absence of Grade 4 events or Treatment Days Lost compares favorably with the published literature.