ESTRO 36 Abstract Book

S17 ESTRO 36 2017 _______________________________________________________________________________________________

testicular classic seminoma (CS) treated with RT and prospectivelly evaluated by abdominal vascular ultrasonography. Material and Methods Forty-two CS patients (median age 34 years, range 16-56) who had undergone radical inguinal orchiectomy were enrolled in this study. Twenty-six patients underwent post-surgery RT (median total dose 25.2 Gy, range 25.05– 43.2), 2 of them also received chemotherapy (CHT), and 16 patients were treated with surgery alone or by surgery followed by CHT (control group).For RT group, dose volume histograms (DVHs) for contoured structures (abdominal arteries and kidneys) were extracted and near maximum dose (D 2% ) and mean dose (D mean ) metrics analyzed. The presence of stenosis in an abdominal vessel and renal resistive index (RRI) were evaluated by abdominal echo-color Doppler and considered as indicators of vascular damage. The presence and severity of stenosis was classified according to validated criteria reported in table 1.

The average RRI (aRRI) over the left and right kidneys was also computed. Statistical analysis was performed first comparing RT group and control-group by Chi-square and Mann-Whitney tests. For RT group, univariate logistic regression analysis was performed by Spearman’s rank correlation coefficient (Rs) to evaluate correlations between different factors with the incidence of stenosis and with RRI. The impact of artery dosimetric factors was analyzed comparing the stenotic arteries versus normal ones. Similarly, the kidney dosimetric analysis was performed on each kidney separately. The area under the Receiver Operator Characteristic (ROC) curve (AUC) was used to evaluate the test accuracy. Results After a median follow-up of 77.4 months (range 48-120 months), stenosis was observed in 8 patients (31%) in the RT group but none in the control group (p=0.016). A significantly higher median aRRI was also observed in the RT group compared with control group (0.63 vs 0.60, p=0.032). Age at RT was the only clinical risk factor for stenosis (Rs=-0.529, p=0.005). Artery mean dose was correlated with stenosis [Rs=0.238, p=0.008, AUC=0.85, 95%CI 0.77-0.91] and kidney mean dose with dichotomized RRI variable using its mean value (0.62) [Rs=0.417, p=0.013, AUC=0.76, 95%CI 0.58-0.89], respectively. ROC curves are displayed in figure 1.a and 1.b.

Conclusion Late vascular damage represents a potential effect of abdominal RT even at moderate-low radiation dose. Younger age at irradiation as well as artery and kidney mean doses are associated with increased risk. Ultrasound-based follow-up may allow for early detection of asymptomatic vascular radiation-induced damage, helping to prevent severe vascular events.

Poster Viewing : Session 1: Haematology / Paediatrics / Sarcoma

PV-0042 Fractionated-TBI schedules prior to allograft: Study from the Acute Leukemia Working Party (EBMT) Y. Belkacemi 1 , M. Labopin 2 , S. Giebel 3 , L. MiszyK 4 , G. Loganadane 5 , M. Michallet 6 , G. Socié 7 , N. Schaap 8 , J. Cornelissen 9 , I. Yakoub-Agha 10 , A. Nagler 11 1 Universite Paris Est Creteil, Radiation Oncology- Hôpitaux Universitaires Henri Mondor- INSERM U955 Eq7, Créteil, France 2 EBMT Paris study office, CEREST-TC- Paris- France. Department of Hematology- Saint Antoine Hospital, Paris, France 3 Maria Sklodowska-Curie Memorial Center Center and Institute of Oncology-, Bone marrow transplantation and Onco-hematology, Gliwice Branch, Poland 4 Maria Sklodowska-Curie Memorial Center and Institute of Oncology, Radiation Oncology, Gliwice Branch, Poland 5 Universite Paris Est Creteil, Department of Radiation Oncology- Hôpitaux Universitaires Henri Mondor, Créteil,