ESTRO 38 Abstract book

S587 ESTRO 38

Median International Index of Erectile Function score before treatment was 15 [10;20] (1-25) and decreased to 10 [4; 10] (1-21) 3 months after HDR-BT. Surprisingly it increased to 12 [4;16] (1-22) after 12 months of follow-up: at that time in 57.6% cases it was above 11 points. Grade I-II late gastrointestinal toxicity detected in 12 cases (6.1%), without any patient with grade III toxicity. Fractionation scheme has no significant impact on early and late toxicity. Conclusion this single center comparative study demonstrated that in patients with localized prostate cancer both fractionation regimes demonstrated high 36-months biochemical control with very limited early and late toxicity. PO-1054 LDR versus HDR brachytherapy boost in prostate cancer patients - a retrospective analysis S. Rodda 1 , L. Murray 1 , D. Bottomley 1 , P. Bownes 2 , C. Wilkinson 3 , E. Adiotomre 4 , B. Al-Qaisieh 2 , E. Dugdale 1 , O. Hulson 4 , J. Mason 2 , J. Smith 4 , A. M Henry 1 1 St.James institute of Oncology, Clinical Oncology, Leeds, United Kingdom ; 2 St.James institute of Oncology, Brachytherapy Physics, Leeds, United Kingdom ; 3 St.James institute of Oncology, Brachytherapy, Leeds, United Kingdom ; 4 St.James institute of Oncology, Radiology, Leeds, United Kingdom Purpose or Objective In the absence of randomised comparison, to report biochemical Progression Free Survival (bPFS) and morbidity outcomes in men with non-metastatic prostate cancer treated with LDR or HDR brachytherapy boost (BT) techniques combined with external beam 347 men consecutively treated with combination of BT boost and EBRT from 1996 – 2012 from a single centre were included. All were staged using prostate MR and bone scan. Data was extracted from a prospectively maintained database and electronic case records. Patients with no record of post implant PSA were excluded from the analysis. 287 patients were evaluable. 116 had LDR (I-125) BT to a dose of 110 Gy in combination with EBRT 45Gy in 20 Fractions (LDR-EB) treated from 1996 to 2007. 171 had HDR BT (17 Gy in 2 fractions or 15 Gy in 1 fraction) in combination with EBRT 35.75Gy in 13 or 37.5Gy in 15 fractions respectively (HDR-EB) treated from 2007-2012. Duration of androgen deprivation was at clinician discretion. Nadir+2 definition was used to define bPFS and toxicity scored using RTOG. Results Median FU was 74.1 and 57.0 months for the LDR-EB and HDR-EB groups respectively. Both groups were relatively well balanced (Table 1). The LDR-EB group were slightly younger than HDR-EB group (63 vs 65 years: p=0.02) and had significantly larger proportion of high risk disease (p=0.02). At 5 years there was a significant improvement in bPFS in LDR-EB compared to HDR-EB groups (90.5% vs. 77.6%, p=0.003). On MVA Gleason grade ≥8 vs 6 (HR: 5.47) and treatment group LDR-EB vs HDR-EB (HR: 2.33) both predicted bPFS. The 5-year cumulative incidence of G3 and above GU and GI toxicity was higher in LDR –EB (8% and 5%) compared to HDR-EB groups (4% and 1%) but did not reach statistical significance. radiotherapy(EBRT). Material and Methods

HDR

-EB

LDR

-EB

P-Value

N=128

N=219

Evaluable Missing Data

patients

116 12(9.5%)

171 48(22%)

Median f/u(Range) months 74.1(1.0-187) 57.0(1.8-116) Median Age (Range) years 10.7(1.6-59) 10(1.4-131) 0.02 Median PSA ng/mL 10.7(1.6-59) 10(1.4-131) ns Gleason Score N (%)

6 7 8-10 Unknown

17 76 21

(15%) (65%) (18%)

20

(12%) (71%) (17%)

121

ns

29

2 (2%)

1 (<1%)

T

category

N

(%)

T1c-T2c T3a-T3b

50 56

(43%) (48%)

69 97

(40%) (57%)

ns

Unknown

10 (9%)

5 (3%)

NCCN Risk group N (%)

2

(2%) (24%) (69%)

2

(1%) (40%) (55%)

Low Intermediate High Unknown

28 80

68 94

0.02

6 (5%)

7 (4%)

Hormone Duration N (%) ≤12 Months >12 months Unknown

74

(64%) (6%)

126

(74%) (16%)

0.06

7

27

35 (30%)

18 (10%)

Conclusion The risk of biochemical failure was more than double in men treated with HDR-EB compared to LDR-EB .There was higher grade 3+ GU and GI toxicity in the LDR-EB group although this has not reached statistical significance. LDR- EB may provide the most effective PSA control at 5 years. The results of this study should be regarded as hypothesis generating in view of it’s retrospective design , lack of randomization and missing data . PO-1055 High-dose rate brachytherapy boost for T3 prostate cancer patients: a single institution experience M. XU 1 , D. Diao 1 , A. Lazar 1 , K. Shinohara 2 , A. Chang 3 , A. Cunha 1 , I. Hsu 1 1 University of California San Francisco, Radiation Oncology, San Francisco, USA ; 2 University of California San Francisco, Urology, San Francisco, USA ; 3 University of California Los Angeles, Radiation Oncology, Los Angeles, USA Purpose or Objective Treating prostate cancer with extraprostatic extension (stage T3a) or seminal vesicle invasion (stage T3b) using brachytherapy boost after external beam radiotherapy (EBRT) enables dose escalation and is technically challenging. Treatment outcomes associated with high- dose rate (HDR) brachytherapy boost for T3 disease have not been well described. This study sought to assess disease control rates among patients treated with HDR brachytherapy boost for T3 disease. Material and Methods