ESTRO 2023 - Abstract Book

S449

Sunday 14 May 2023

ESTRO 2023

Figure 1 shows results of the receiver operator characteristics analysis for the clinical signatures, radiomic signatures and clinical-radiomics signature at 24 months of follow up based on repeated nested cross validation (test results in the outer fold) results. Conclusion This is the first study to develop a CT-based radiomic model to predict BCR after PSMA-PET guided sRT. The radiomic models outperformed clinical models and might contribute to guide personalized treatment decisions. PD-0568 Prostate radiotherapy may cause fertility issues – analysis of testicular dose following modern RT M. Kissel 1 , M. Terlizzi 1 , N. Giraud 2 , A. Alexis 3 , M. Cheve 3 , J. Vautier 3 , A. Bossi 1 , P. Morice 4 , P. Blanchard 1 1 gustave Roussy, Radiotherapy, Villejuif, France; 2 chu Bordeaux, Radiotherapy, Bordeaux, France; 3 gustave Roussy, Radiophysics, Villejuif, France; 4 gustave Roussy, Gynecologic Surgery, Villejuif, France Purpose or Objective Prostate cancer in younger men is not infrequent. Radiotherapy is a cornerstone of prostate cancer treatment and yet, its impact on fertility is scarcely reported in literature. Since testis is one of the most radiosensitive tissue, we tried to determine testicular dose with modern radiotherapy techniques for a definitive prostate irradiation. Materials and Methods One hundred radiotherapy plans were reviewed. Testicles were contoured a posteriori without any optimization on testicles. Results Median testicular dose was 0.58 Gy: 0.18 Gy in stereotactic plans versus 0.62 Gy in Volumetric Modulated Arc Therapy plans versus 1.50 Gy in Tomotherapy plans (p < 0.001). Pelvic nodal irradiation increased the median testicular dose: 1.18 Gy versus 0.26 Gy (p < 0.001). Weight and BMI were inversely associated with testicular dose (p < 0.005). 65% of the patients reached the theoretical dose threshold to get transitory azoospermia and 10% received more than 2 Gy, that is likely to give definitive azoospermia.

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