ESTRO 2021 Abstract Book

S1153

ESTRO 2021

Toxicity data was available for 42% of patients. 75% of patients experienced lower urinary tract symptoms 44% G1, 25% G2 and 6% G3. Other frequent side effects included fatigue (39%) and GI toxicity (22%). Overall G3 toxicity was 8%.

Number Percentage PFS (months) OS (months) p-value

Overall

85

100%

7.1

8.6

Fractionations completed 6

72

85%

8.0

9.5

0.00002

<6

13

15%

1.7

2.3

Tumour staging

T2

50

58%

12.0

14.2

0.0022

T3/4

35

42%

5.5

7.2

Metastatic status

M0

78

92%

9.8

11.0

0.0026

M1

5

6%

1.0

2.6

Histology

urothelial

72

85%

9.8

11.0

0.520

non-urothelial 13

15%

4.4

4.4

Conclusion Our cohort of patients treated with high dose palliative radiotherapy had a shorter 8.6 months OS compared to 18.9 months OS reported in the HYBRID trial. Local control outcomes were similar with >80% initial local control and 77% local control at longer term follow up. Lower OS was likely due to patient selection with 59% PS >=2; 18% N1 or M1 disease and 15% non-urothelial carcinoma. Treatment was well tolerated with G3 toxicity of <10%. Age >80 was not found to be an important prognostic factor however completing <6 fractions, T3+ and M1 patients did significantly more poorly reflecting that a shorter regimen may have been more appropriate.

PO-1404 Reduction of margins in bladder cancer treatment to minimize normal tissue irradiation I. Bengtson 1 , S. Talozi 1 , A. Gunnlaugsson 1 , J. Scherman 1 , E. Wieslander 1 1 -, Department of Hematology, Oncology and Radiation Physics, Lund, Sweden

Purpose or Objective