Radiosensitivity of Koch ileal reservoir

To acquire preliminary information on the radiosensitivity of the Koch ileal reservoir by reviewing acute and late toxicity incurred by nine patients who received pelvic radiotherapy after cystoprostatectomy with lower urinary reconstruction utilizing a Koch ileal reservoir with bilateral uretero-ileal-urethrostomy.

All patients were irradiated because of synchronous locally advanced prostate cancer (pT3). A fourfield box technique at 100 cm source-axis-distance (SAD) with all fields treated every day at 1.8 Gy daily fractions, to a total dose of 45-50.40 Gy was used. The average AP portal dimension was 11 x 11 cm, and the average lateral was 7 x 8 cm. All portals were shaped using custom shields to optimize protection of normal tissues not suspected of tumor involvement (small bowel, posterior rectal wall). No attempt was made to shield the Koch ileal reservoir. For each patient, comparison of the treatment portals with the Kochgram radiography (gravity cystogram) confirmed the inclusion of the majority of the Koch ileal reservoir within the radiation fields. Acute and late morbidity was measured by RTOG toxicity criteria by retrospectively reviewing the patients' records.

Only mild acute toxicity was reported by the patients: Six patients experienced grade 1 acute urinary toxicity and one suffered Grade 2 acute urinary toxicity. In four patients Grade 1 acute gastrointestinal toxicity occurred and in two patients Grade 2 toxicity occurred. With a median follow-up of 50 months late toxicity consisted mainly of microscopic hematuria in six patients and persistent frequency in two patients (with spontaneous improvement respectively at 4 and 6 months after radiation). No patients experienced acute or late Grade 3 or 4 genitourinary or gastrointestinal toxicity.

The use of moderate doses of pelvic radiotherapy (45-50.40 Gy) at standard fractionation was well tolerated among nine patients who received pelvic radiation for invasive prostate cancer detected at the time of cystectomy and Koch ileal reservoir diversion. These preliminary data support the evidence that patients with a Koch ileal reservoir could safely undergo postoperative pelvic radiotherapy in these dose ranges and fractionation.