Intraoperative electron-beam radiotherapy and ureteral obstruction.

PURPOSE: To quantify the risk of ureteral obstruction (UO) after intraoperative electron-beam radiotherapy (IOERT).

METHODS AND MATERIALS: One hundred forty-six patients received IOERT of 7.5 to 30 Gy to 168 ureters; 132 patients received external radiotherapy.

RESULTS

Follow-up ranged from 0.01 to 19.1 years (median, 2.1 years). The rates of clinically apparent type 1 UO (UO from any cause) after IOERT at 2, 5, and 10 years were 47%, 63%, and 79%, respectively. The rates of clinically apparent type 2 UO (UO occurring at least 1 month after IOERT, excluding UO caused by tumor or abscess and patients with stents) at 2, 5, and 10 years were 27%, 47%, and 70%, respectively. Multivariate analysis revealed that the presence of UO before IOERT (p < 0.001) was associated with an increased risk of clinically apparent type 1 UO. Increasing IOERT dose (p < 0.04) was associated with an increased risk of clinically apparent type 2 UO. UO rates in ureters not receiving IOERT at 2, 5, and 10 years were 19%, 19%, and 51%, respectively.

CONCLUSIONS

Risk of UO after IOERT increases with dose. However, UO risk for ureters not receiving IOERT was also high, which suggests an underlying risk of ureteral injury from other causes.