Abstract book - ESTRO meets Asia

S103 ESTRO meets Asia 2018

and EPIC. The change of urinary function was significant for 9/10 evaluable studies at 1-month follow-up, 4/10 (12- month), 2/9 (24-month) and 1/4 (36-month). Conclusion Change of patient-reported genitourinary symptoms were significant following extreme hypofractionated prostate RT (≥5Gy/fraction) which appeared to be ameliorated and returned to baseline by 2 years in most studies. Confirmation from randomised controlled trials is required. (GRANT: GGPM-2017-095) PO-250 Relationship between tumor movement and treatment outcomes in tumor-tracking prostate SBRT H. Jeong 1 , H.S. Choi 2 , K.M. Kang 1 , C.H. Kim 2 , I.B. Ha 3 , Y.H. Lee 3 , J.H. Song 3 , B.K. Jeong 1 1 Gyeongsang National University, Radiation Oncology- School of Medicine, Jinju-si, Korea Republic of 2 Gyeongsang National University Changwon Hospital, Radiation Oncology, Changwon, Korea Republic of 3 Gyeongsang National University Hospital, Radiation Oncology, Jinju-si, Korea Republic of Purpose or Objective Image-guided radiotherapy has been introduced to improve the accuracy of treatment by identifying tumor movement during treatment. However, the effect of tumor movement on the treatment outcome of treatment have not been well studied. The purpose of this study is to quantitatively investigate the direct relationship between tumor movement and treatment outcome in tumor- tracking stereotactic body radiotherapy (SBRT) for prostate cancer. Material and Methods We retrospectively reviewed the medical records and daily treatment records of 71 patients who underwent Cyberknife-based tumor-tracking SBRT. Local recurrence, biochemical failure and treatment-related toxicities to rectum and bladder were assessed from the medical records and the correlation of the results with the intra- fractional prostate motion, which was measured by the fiducial tracking method and recorded in each daily treatment logs, were statistically analyzed. Results In a total 71 patients, 3 (4.2%) patients with local recurrence (LR), 12 (16.9%) patients with biochemical failure (BF), and 22 (31%) patients with grade-II or worse toxicities to rectal or bladder (22 to rectal, 22 to bladder and 8 patients to both) were observed in a median follow- up of 47 months. Magnitudes of intra-fractional tumor motion along superior-to-inferior, right-to-left, and anterior-to-posterior axes were measured as 0.15 ± 0.31(mean±standard deviation), 0.12 ± 0.19, and 0.73 ± 0.32 mm, respectively, and the overall radial movements of the intra-fractional prostate motion was estimated as 1.0 ± 0.35 mm.

treatment-related toxicities in rectum and bladder were sensitively increased with increase in the AP-directional prostate motion.

Conclusion In conclusion, intra-fractional prostate movement was found to have significant correlation with treatment- related toxicity, but not with tumor control, in tumor- tracking SBRT for prostate cancer. Particularly, AP- directional movement showed a strong correlation with treatment-related toxicity. Our results quantitatively show that tumor movement is related not only to the treatment of the tumor itself, but also to the toxicity to the surrounding organs. PO-251 Image Guided High Dose Rate (HDR)-Brachytherapy Boost in localized Carcinoma of Prostate V. Anand 1 , S. Deshpande 1 , V. Kannan 1 , R. Bajpai 1 , S. Nagshet 1 , V. Babu 1 , S. Naidu 1 , S. Nagoankar 2 , V. Joshi 2 , S. Sagade 2 , S. Almel 1 , M. Shaikh 1 , A. Kapadia 1 1 PDHinduja National Hospital and MRC, Radiation Oncology Department, Mumbai, India Purpose or Objective Escalated radiation dose delivery has been the mainstay in tumor control of localized prostate cancer. Combined treatment by external beam radiotherapy (EBRT) and high-dose-rate brachytherapy boost (HDR-BT) in locally advanced prostate carcinoma has shown that dose escalation is possible for better tumor control and with fewer normal tissue complications. Material and Methods From 2009 to 2017, 70 patients with diagnosed adenocarcinoma of prostate were assigned to EBRT followed by HDR-BT. Patients were stratified as low, intermediate and high risk according to D’amico risk group stratification of prostate cancer. All patients received one or two fractions (8-15 Gy) of HDR brachytherapy boost following EBRT dose of 37.75 to 60 Gy. Overall survival (OS) and Biochemical recurrence-free survival (BRFS) were the primary endpoints. Secondary endpoints were, late Gastro-intestinal (GI) and Genito-urinary (GU) complications. Biochemical recurrence was defined according to the phoenix definition 1 . Results Mean age of the patients was 69.4 years (49-84). Out of 70 patients, 8 (11.4%) were of intermediate risk and 62 (88.6%) patients of high-risk prostate cancer. After a median follow up of 55 months (7-111), 8 of the 8 (100%) patients belonging to intermediate risk group had BRFS and OS, among the high-risk group 57 (91.9%) patients had BRFS and OS in 47 (75.8%) of the 62 patients. GI complications of Grade (Gr) I were seen in 1.4%, Gr III in 1.4% of patients and GU complications of grade I & II were seen in 42.8% and Gr III in 7.1%. Conclusion Combination of HDR-BT and EBRT achieves better dose escalation than any other modality in the radical 2 PDHinduja National Hospital and MRC, Department of Urology, Mumbai, India

The measured intra-fractional movement did not show a significant correlation with the tumor-control related factors including LR and BF. However, it showed the significant relationship with the treatment-related toxicities to rectum and bladder. Particularly, the