ESTRO 37 Abstract book

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ESTRO 37

Results In the well balanced patient group of 205 patients, 172 were treated as per protocol, being mainly in UICC-stage IIIa (36%) and IIIb (56%) with GTVs of in mean 105 ml. Dose escalation (realized by 3-D-CRT (50%) or IMRT (50%)) reached in mean 65.3 Gy (A) and 67.3 Gy (B; p=0.007). Loco-regional progression (LRP) was more frequent in arm A (conventional target volume) with a cumulative incidence of 0.29 / 0.39 vs. 0.14 / 0.20 (arm B) after 12 / 24 months (p=0.078). In stratified Cox-models, independent prognostic factors for LRP were study center (p=0.046) and tumor volume (GTV) (p=0.022) while study arm did not reach statistical significance. The 2-year overall survival was 57% (A) vs. 54% (B; n.s.). Neither for local control nor for survival, a positive or negative influence of radiotherapy dose was observed. The first site of tumor progression were distant metastases (A: 56% vs. B 72%; n.s.) followed by the primary tumor (A: 44% vs. B: 26%, p=0.032), in-field- (A: 23% vs. B: 11%; n.s.) and out-field- (A: 11% vs. B: 8%; n.s.) regional nodes. Acute and late toxicity (CTC/ RTOG-EORTC) was mild with no clinically significant difference between the treatment arms. However, SUEs appeared more frequent in arm B. Conclusion In the setting of isotoxically dose escalated radio- chemotherapy, the outcome after merely FDG-PET based radiotherapy planning was not inferior to that after conventional planning. It enabled higher dose escalation and a clear trend to improved local control. Survival well compared to other recent trials. In contrast to RTOG 0617, we did not observe any adverse effect of higher treatment doses. OC-0599 Ultrahypofractionation for prostate cancer: Outcome from the Scandinavian phase 3 HYPO-RT-PC trial A. Widmark 1 , A. Gunnlaugsson- 2 , L. Beckman 3 , C. Thellenberg-karlsson 1 , M. Hoyer 4 , M. Lagerlund 5 , P. Fransson 1 , B. Tavelin 1 , D.B. Norman 6 , J. Kindblom 7 , C. Ginman 8 , B. Johansson 9 , M. Seke 10 , k. Björlinger 11 , m. Agrup 12 , e. Kjellen 13 , l. Franzen 1 , p. Nilsson 14 1 umea university, radiation sciences/onkology, umeå, sweden 2 skåne university hospital- lund university, dept. Of oncology and radiation physics, lund, sweden 3 umeå university, sundsvall hospital- sundsvall- and dept. Radiation sciences, sundsvall, sweden 4 aarhus university hospital, danish centre for particle therapy, aarhus, denmark 5 kalmar hospital, department of oncology, kalmar, sweden 6 umea university hospital., regional cancer centre north, umeå, sweden 7 university of gothenburg-, department of oncology- institute of clinical sciences- the sahlgrenska academy, gothenburg, sweden 8 karlstad central hospital, department of oncology-, karlstad, sweden 9 örebro university hospital and örebro university, department of oncology, örebro, sweden 10 centrallasarettet växjö, department of oncology-, växjö, sweden 11 jönköping hospital, department of oncology, växjö, sweden 12 linköping university hospital-, department of oncology-, linköpingt, sweden 13 skåne university hospital- lund university-, dept. Of oncology and radiation physics- -, lund, sweden 14 skåne university hospital- lund university-, dept. Of oncology and radiation physics, lund, sweden This abstract is part of the media programme and will be relased on the day of its presentation

OC-0600 Long term risk of stroke after childhood cancer radiotherapy F. De Vathaire 1 , C. El - Fayech 2 , N. Haddy 3 , R. Allodji 4 , C. Veres 4 , D. Llanas 4 , N. Journy 4 , V. Souchard 4 , C. Rubino 4 , H. Pacquement 5 , C. Teinturier 4 , B. Fresneau 2 , G. Vu- Bezin 4 , S. Bolle 6 , A. Mazal 7 , P. Poortmans 8 , E. Deutsch 6 , I. Diallo 4 1 institut gustave roussy, academic physics, villejuif, france 2 institut gustave roussy, pediatry, villejuif, france 3 inserm, unit 1018 - cancer and radiation team, villejuif, france 4 inserm, unit 1018 - cancer and radiation team, villejuif, france 5 institut curie, pediatry, paris, france 6 institut gustave roussy, radiotherapy, villejuif, france Purpose or Objective Stroke is one of the major potential long term iatrogenic risk of childhood cancer radiation therapy. Nevertheless, present knowledge is insufficient to predict the long-term risk of stroke following radiation therapy as the dose- response to fractionated high doses of radiatiation to brain is not known Material and Methods We carried out an analysis in a cohort of 7030 5-years survivors of a solid childhood cancer treated in France before 2001, of whom 4150 by radiotherapy, and followed 20 years in average, by self-questionnaire and cross-linkage with French National Hospital and Medical InsDatabase (SNIIR-AM) . During the follow-up, 139 patients developed a permanent stroke, which could be validated. Each of them was matched with 8 controls of the same cohort, on gender, age at childhood cancer and follow-up duration. Radiation dose distribution in cerebral arteries was individually esimated by reconstructing radiotherapy of each case and control treated by radiotherapy, using medical records and anthropometric phantoms. Risk of stroke as modeled as a function of average radiation dose to cerebral arteries, as well as using dose volume parameters used in classical NTCP models (VxGy and Dx%). Receiving Operating Characteristic (ROC) curves were also established. Results As compared to children not treated by radiation therapy, and when controlling for chemotherapy, children who received less than 1 Gy in average, to the cerebral arteries had a 1.8 (95%CI: 0.80-3.9) times higher risk of stroke, whereas those who received more than 20 Gyin aveage to cerebral arteries had a risk 26 (95%CI : 10-68) times higher. These risk factors were higher for ischemic strokes than for haemorrhagic ones. To take into account dose-volume parameters allowed to improve these risk predictions. High radiation doses strongly increased stroke risk. As an exemple,to have received during childhood 30 Gy or more to only 1 to 5% of the cerebral arteries volume increased the long term risk of stroke by a factor 2.8 (1.3-5.5). Conclusion This study confirms that average radiation dose to the cerebral arteries is not the best parameter for predicting long term risk of stroke. Classical dose-volume parameters may be used for such predictions, even if established on antropomorphic phantoms in retrospective studies 7 institut curie, medical physics, paris, france 8 institut curie, radiotherapy, paris, france

Proffered Papers: PH 11: Emerging technologies