Temporary Organ Displacement to Escalate Radiation Dose to Retroperitoneal Tumors and Decrease Toxicity to Organs at Risk.

PURPOSE: To demonstrate that temporary organ displacement (TOD) by drainage catheter placement and hydrodissection is feasible and reproducible for simulation (SIM) and stereotactic body radiation treatment (SBRT).

MATERIALS AND

METHODS

Between February 2010 and December 2018, 31 consecutive patients (20 men and 11 women; median age, 59 years; range 20-80 years) received both SIM and SBRT with TOD. The minimum required displacement was 10 mm between the gross tumor volume (GTV) and the organ at risk (OAR). Complete displacement was defined as the ability to displace the OAR from the GTV a minimum of 10 mm across the entire boundary. SIM was performed with hydrodissection on the same day. On the day of SBRT, displacement was reproduced by hydrodissection. Displacement was measured on computed tomography images of TOD, SIM, and SBRT. The drain was removed after SBRT.

RESULTS

TOD (hydrodissection) was significantly associated with successful displacement of the OAR from a GTV greater than 10 mm (median, 20 mm vs 4.1 mm, P < .001) and maintained displacement at SIM and SBRT (SIM: 29.4 mm vs 4.1 mm, P < .001; SBRT: 32.4 mm vs 4.1 mm, P < .001). The OAR-GTV boundary showed a median reduction of 35 mm (95% confidence interval, 27.5-37.5 mm) after TOD. TOD achieved complete displacement in 22 of 31 (71%) patients, and 25 of 31 (81%) patients were able to undergo single-fraction ablative SBRT. No patients developed procedure-related complications within 30 days. SIM and SBRT were successful without OAR toxicities within a median of 33 months (range, 3-92 months).

CONCLUSIONS

TOD with placement of drain and hydrodissection is technically feasible and safe and maintains displacement for SIM and SBRT.