ESTRO 36 Abstract Book

S531 ESTRO 36 2017 _______________________________________________________________________________________________

Tube feeding during treatment was given in 24%, for HAS, ASO and ARCON 32%, 25% and 17% (p=ns). Severe late laryngeal was equal for the schedules (table 1). HyperfractionatedAcc.

rectum and bladder. Six blood samples were collected from each patient; pre-treatment, 1 hour (h) post implant, 4h, 24h, 4weeks (w) and at 3 months (m). DNA double strand breaks were stained using the γH2AX and 53BP1 proteins. Patient self-scored quality of life from the Expanded Prostate Cancer Index Composite (EPIC) were obtained at baseline , 1 m, 3m, 6m, 9m, 1 year (y), 2y and 3y post treatment. Spearman’s correlation coefficients were used to evaluate correlations between temporal changes in γH2AX, dose and toxicity Results The minimum follow-up was 2 years. Population mean prostate D 90% was 144.6±12.1 Gy. Rectal near maximum dose D0.1cc = 153.0±30.8 Gy and D2cc= 62.7±12.1 Gy and bladder D0.1cc = 123.1±27.0 Gy and D2cc = 70.9±11.9 Gy. Pre-treatment, mean (±SD) background foci (co-localising γH2AX and 53BP1) was 0.42±0.20 foci per cell (Figure 1B). A Shapiro-Wilk test confirmed the data was normally distributed (w=0.943, p=0.540). Post seed implantation, γH2AX/53BP1 foci numbers were significantly elevated as early as 1 hour post implantation and remained so at 4 and 24 hours, 4 weeks and 3 months post implantation (Figure 1B). The γH2AX/53BP1 foci numbers continued to rise at 4 weeks (672 h) even after reduction in seeds activity due to natural decay (Figure 2A) before dropping at 3 months. EPIC summary scores for bowel, urinary, and sexual domains are presented in Figure 2. Changes in EPIC scores from baseline showed high positive correlation between acute toxicity and late toxicity for both urinary and bowel symptoms. Increased production of γH2AX at 24h relative to baseline positively correlated with late bowel symptoms, EPIC 1y (r= 0.67, p = 0.035), EPIC 2 y (r=0.86, p = 0.001). Overall, no correlations were observed between dose metrics (prostate global or sector doses) and γH2AX foci counts.

Acceleratated fractionation only (ASO) 1 ; n=283 40; 2/1.8/1.5;33 Wk 1-2: 10 x 2 Gy

ARCON study 2

Fractionation (HAS) 1 n=28

n=86 p

n (fractions); d (Gy); T (overall treatment time in days)Total Dose: ERD (α=0.3, α/ β =10, Tpot=5)

50;1.2/1.7; 33 Wk 1-3: 30 x 1.2 Gy, BID Wk 4-5: 20 x 1.7 Gy, BID70 Gy

4; 2; 37 Wk 1-4: 20 x 2 Gy Wk >5, 14 x 2Gy, BID68 Gy

Wk 3-5: 15 x 1.8/1.5 Gy, BID69.5 Gy

67.7

66.5

64.5

ETD (α/ β=10) 5 yr local control 5 yr disease free Serious late toxicity (larynx)

103.7

116.9

113

56%

83%

75%

0.004

50%

76%

65%

0.02

12%

10%

12%

ns

Conclusion In this large group of patients treated for intermediate size laryngeal/ hypopharyngeal cancer superior local control and disease free survival was seen when the accelerated fractionation started in week three. The rate of serious toxicity was equal for all three schedules. Also, age ≥ 70 was not a negative prognostic factor for local control, disease free survival and risk of complications.. For patients ≥ 70, with a WHO performance 0-1 excellent outcome is shown. 1: Terhaard IJRBP. 2005 May 1;62(1):62 2. Janssens C Oncol. 2012 May 20;30(15):1777-83. Poster: Radiobiology track: Radiobiology of prostate cancer PO-0970 Prostate brachytherapy; DNA damage biomarker (gH2AX) induction rate correlates with late toxicity S. Osman 1 , S. Horn 1 , D. Brady 1 , S.J. McMahon 1 , A.B. Mohamed Yoosuf 2 , D. Mitchell 3 , K. Crowther 2 , C.A. Lyons 1 , A.R. Hounsell 2 , K.M. Prise 1 , C.K. McGarry 2 , S. Jain 1 , J.M. O’Sullivan 1 1 Queen's University Belfast, Centre for Cancer Research & Cell Biology, Belfast, United Kingdom 2 Northern Ireland Cancer Centre- Belfast Health and Social Care Trust, Radiotherapy Physics, Belfast, United Kingdom 3 Northern Ireland Cancer Centre- Belfast Health and Social Care Trust, Clinical Oncology, Belfast, United Kingdom Purpose or Objective Low-dose-rate permanent prostate brachytherapy (PPB) is an attractive treatment option and offers excellent outcomes for patients with localised prostate cancer. As standard CT-based post-implant dosimetry often correlates poorly with late treatment toxicity, a study was conducted to investigate correlations between radiations induced DNA damage biomarker levels, bowel, urinary, and sexual toxicity Material and Methods Twelve prostate cancer patients treated with 125 I PPB monotherapy (145Gy) were included in this prospective study. Post-implant CT based dosimetry assessed the minimum dose encompassing 90% (D 90% ) of the whole prostate volume (global), sub-regions of the prostate (12 sectors) and the near maximum doses (D 0.1cc , D 2cc ) for the