Use of expanders for bowel protection in pediatric pelvic tumor radiation therapy: 15 years of tolerance results.

PURPOSE

Bowel is often the dose-limiting organ in curative pelvic irradiation because of radiation enteritis when dose exceeds 40 to 45 Gy. To limit radiation enteritis, a silicone tissue-expander prothesis (STEP) connected to a subcutaneous self-sealing valve was prospectively used in children undergoing pelvic or abdominal radiation therapy. This study reports the 15-year long-term outcomes of this prospective series.

METHODS AND MATERIALS

Between 1987 and 2008, 29 children from 3 Paris institutions received pelvic radiation therapy after surgical placement of a STEP in the pelvis. The median prescribed dose was 50.4 Gy (44.1-55 Gy) using 5 daily fractions of 1.8 Gy per week, except for 1 patient receiving 4 fractions of 2.5 Gy per week. The median treatment duration was 40 days (29-49 days). After 2000, computed tomography (CT) conformal 3-dimensional radiation therapy was used, and 12 patients had CT simulation. Four had CT before and after insertion of the STEP, enabling us to compare pre- and postprosthesis insertion bowel dose-volume histograms. Acute and late toxicities were captured using the Radiation Therapy Oncology Group or the National Cancer Institute Common Terminology Criteria for Adverse Events 4.0 scale.

RESULTS

No patient experienced significant perioperative complications. Pre- and post-STEP insertion small bowel dose-volume histograms show significant reductions in small bowel: 51%, 45%, and 64%, respectively, in V, V, and V (V = irradiated volume by x Gy). Twenty-five patients (86%) completed their radiation therapy with no or minimal small bowel toxicity. One patient also treated with neutrons developed delayed grade 4 toxicities. The 15-year complication-free survival for those surviving was 70.3%.

CONCLUSIONS

We report the long-term follow-up of STEP prosthesis insertion in children to reduce the small bowel volume in the radiation field. The acute and long-term tolerances were excellent. The STEP reduced the bowel dose over 40 Gy by 64%.