ESTRO 2025 - Abstract Book

S4057

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2025

group had cT3 disease compared to 12 (40%) patients in the control group. The spacer group demonstrated a mean rectal-prostate separation distance of 0.97 cm (range: 0.31 – 1.39), significantly greater than the control group of 0.12 cm (range: 0 – 0.58; P < 0.001). Dosimetry revealed a lower rectal mean dose in the spacer group at 25.6Gy (range: 21.1 – 32.0) compared to the control group 29.7Gy (range: 26.4 – 33.8; P = 0.001). Similarly, the rectal D1cc was significantly lower in the spacer group at 53.9Gy (range: 40 – 59) compared to the control group of 58.7Gy (range: 56 – 60; P < 0.001). EPIC-26 survey results showed no statistically significant difference in the overall bowel domain between the 2 groups. Interestingly, in the high-risk subgroup (cT3), a trend towards significance was observed in the overall bowel habits and urgency domains (Spacer: 97.1%; Control: 82.5%; P=0.061).

Conclusion: We observed a trend toward improved bowel function in the high-risk T3 disease group, suggesting a potential subgroup of patients that could benefit from hydrogel spacer technology.

Keywords: hydrogel spacer, prostate, QoL, rectal toxicity