ESTRO 36 Abstract Book

S694 ESTRO 36 2017 _______________________________________________________________________________________________

significance in late (3 and more months) GI and GU toxicities between two groups. Conclusion post-prostatectomy SRT, when using CF, requires 33 – 36 fractions. We would like to suggest a new differentiated approach of hypofractionation radiotherapy for patients with recurrence PCa after RP which demonstrates encouraging efficacy at 3 years without increasing level of late toxicities and reduces the length of treatment by from 21% – 28%. EP-1309 Is it necessary to make a re-plan during IMRT for prostate cancer due to change in prostate size? O. Tanaka 1 , H. Komeda 2 , T. Iida 1 , M. Tamaki 2 , K. Seike 2 , T. Yokoyama 1 , D. Kawaguchi 1 , S. Hirose 1 , S. Fujimoto 2 1 Gifu Municipal Hospital, Department of Radiation Oncology, Gifu, Japan 2 Gifu Municipal Hospital, Department of Urology, Gifu, Japan Purpose or Objective Intensity-modulated radiotherapy (IMRT) is a widely used treatment modality for prostate cancer. The technique helps deliver the prescribed dose to the target volume with minimal radiation exposure of the organs at risk (OAR). Gunnlaugsson et al. reported a significant increase in mean prostate volume (14%) at mid-point of the radiotherapy course as compared to that at baseline. The increase in mean prostate volume tended to persist during the radiotherapy course; the mean prostate volume at the completion of the radiotherapy was 9% higher than that at baseline. The increase in prostate volume was most pronounced in the anterior-posterior and cranio-caudal axes. However, most of the data used emanated from studies conducted in Europe and America, while data based on Asian population has been largely lacking. Tanaka et al. measured prostatic size prior to prostate cancer brachytherapy and reported mean prostate volume of approximately 16 cc (including data from patients who had received neoadjuvant hormonal therapy). The implications of change in prostate size for IMRT planning in patients with small prostate glands are not known. Therefore, we evaluated the relatively small changes in size of prostate during IMRT using MRI. Material and Methods A total of 24 consecutive patients with prostate cancer were enrolled in the study. None of the patients received hormone treatment (neoadjuvant therapy) either prior to or during the course of radiotherapy. Two gold fiducial markers were placed on the prostate before a CT/MRI examination at 3 weeks. MR imaging was performed at three timepoints. The initial MRI was performed prior to the start of radiotherapy. Second MRI was performed at 38 Gy (range: 36–40 Gy), which represented the halfway point of the radiotherapy course. The last MRI was performed at the completion of the radiotherapy course.

<5. 0 vs ≥5. 0 <2. 5 vs ≥2. 5 <30 0 vs ≥30 0 <20 00 vs ≥20 00

Lymphocyte- to-Monocyte ratio (LMR) Neutrophil-to- Lymphocyte ratio (NLR)

4.6 (1.14- 12.5) 3.8 (0.11- 22.6) 160 (11.8- 647.0)

56.5 vs 63.8 63.5 vs 56.3 61.5 vs 33.0

,036 (4.42)

112

8 vs 2

2 vs 10

,008 (7.1)

131

Platelet-to- Lymphocyte ratio (PLR)

.000(1 3.4)

129

9 vs 3

Platelet*Neutr ophils-to- Lymphocyte (SII)

906.5(2 7.2- 5094.3)

61.4 vs 40.9

.003(9. 1)

129

9 vs 3

Conclusion Preoperative NLR, LMR, PLR and SII are predictive factors for Overall Survival in endometrial carcinoma. To our knowledge, this is the first publication describing predictive value of SII in endometrial carcinoma.

Electronic Poster: Clinical track: Prostate

EP-1308 A prospective trial of hypofractionation salvage radiation therapy after radical prostatectomy P. Bulychkin 1 , S. Tkachev 1 , A. Nazarenko 1 1 Federal State Budgetary Institution “N. N. Blokhin Russian Cancer Research Center”- the Ministry of Health of the Russian Federation, Department of radiation oncology, Moscow, Russian Federation Purpose or Objective to estimate and compare local control (LC), disease – free survival (DFS), overall survival (OS) and toxicity of hypofractionation (HF) and classical fractionation (CF) salvage radiation therapy (SRT) in treatment of patients with biochemical and clinical recurrences of prostate cancer (PCa) after radical prostatectomy (RP). Material and Methods patients with biochemical and clinical recurrences of PCa after RP were divided in two groups. The first one is a group of patients who were treated by HF SRT. HF radiotherapy have been prescribed to the regional lymphatic nodes to 46.8 Gy of 1.8 Gy, to the prostate bed to 61.1 Gy of 2.35 Gy and to recurrent lesions detected by multi-parametric magnetic resonance imaging (MRI) 65 Gy of 2.5 Gy in 26 fractions using simultaneous integrated boost (SIB). The second one is a group of patients who were treated by CF SRT. CF radiotherapy have been prescribed to the regional lymphatic nodes to 44 Gy, to the prostate bed to 66 Gy and if region of clinical recurrence identified to 72 Gy in 33 – 36 fractions. Results median follow up for all 92 patients was 40 (12 – 78) months. OS – 100%. LC – 100%. The rates of 1, 2 and 3 year DFS were 96 %, 91 % and 86 %. The rates of 1, 2 and 3 year DFS were 98%, 95 % and 89 % in group of patients who were treated by HF SRT. The rates of 1, 2 and 3 year DFS were 95%, 87% and 84% in group of patients who were treated by CF SRT. We have not received statistical significance in DFS between the two groups (p = 0.125). On multivariate analysis, PSA doubling time ≤ 6 months (p = 0.035) and PSA > 0.5 ng/ml before SRT (p = 0.037) statistical significance associated with biochemical failure. We received a trend to an increase number of patients with symptoms acute gastrointestinal (GI) (p = 0.057) and genitourinary (GU) (p = 0.07) toxicities 2 grade in the group of HF SRT. But we have not received statistical

An example of the time course of prostate volume change.