Abstract book - ESTRO meets Asia

S102 ESTRO meets Asia 2018

Clinical: Prostate

Nineteen patients, named VMAT-SBRT group, were irradiated 35 Gy in 5 fractions. Meanwhile or previously other 32 patients were received 76 Gy in 36 fractions as CF-VMAT group. Androgen deprivation therapy (ADT) was not used to these 51 patients. T category, initial PSA (iPSA), Gleason Score (GS), and age of the patients were selected as confounding factors. CRAN R software was used for Wilcoxon rank sum (W) test, Fisher's exact (F) test and propensity score (PS) matching. Results As VMAT-SBRT vs. CF-VMAT, numbers of patients of (T1c, T2a, T2b, T2c) were (5, 10, 4, 0) vs. (14, 14, 2, 2), respectively. Mean values of iPSA, GS (primary + secondary) and age were 8.44 ng/ml vs. 8.22 ng/ml, (3.3 + 3.4) vs. (3.2 + 3.4), 74.8 y. o. vs. 72.7 y. o., respectively. There were no significant differences among them (F test, W test). Mean values of initial half-time were 75.9 ds. vs. 128.3 ds. Difference was significant (p < 0.0005, W test). After PS matching, using scoring model; Mode~ T + GS_primary + GS_secondary + Age + T: GS_secondary + GS_primary: GS2_secondary + GS_secondary: Age, where the area under the receiver operating characteristic curve was 0.81, mean values of initial half-time were 75.0 ds. vs. 110.7 ds. (p < 0.0005). Conclusion Because the VMAT-SBRT cases were our early experience of this technique, so we used PS matching to withdraw selection deviation. Initial half-time of PSA without ADT was significantly shorter about one month in the cases of VMAT-SBRT compared to the cases of CF-VMAT. Radiobiological events related to high-dose fraction such as apoptosis may affect this phenomenon. Rapid decrease of PSA may lead to good anticipation of this disease by this technique. PO-249 Genitourinary Outcome of Extreme Hypofractionated Prostate RT (≥5Gy/fraction): A Systematic Review N.A.B. Yahya 1 , N. Huzail 1 , H.A. Manan 2 , M.M. Abdullah 3 1 The National University of Malaysia, Faculty of Health Sciences, Kuala Lumpur, Malaysia 2 The National University of Malaysia, Faculty of Medicine, Kuala Lumpur, Malaysia 3 Ramsay Sime Darby Medical Centre, Radiation Oncology, Subang Jaya, Malaysia Purpose or Objective Experimental and clinical studies have suggested that the α / β ratio for prostate cancer may be low (~1.5) which have prompted the utilisation of hypofractionated radiotherapy (HRT) including extreme dose/fraction (ExHRT) prescribed with stereotactic RT. A systematic review was conducted to evaluate the pattern of genitourinary outcome for studies utilising EHRT with dose per fraction ≥5Gy/fraction focusing on patient-reported measures. Material and Methods A systematic review of Medline database was performed following the PRISMA guidelines. Included studies were retrospective or prospective cohorts that 1) have population of ≥40 patients, 2) delivered RT exclusively using external-beam photon ExHRT (≥5Gy/fraction), 3) reported on genitourinary outcomes at different timepoints relative to baseline using patient-reported measures. Descriptive statistics were generated for included studies. Results Of 196 initial studies, 12 met eligibility criteria for inclusion, reporting on patient-reported urinary outcome relative to baseline of 1637 patients. No phase III randomised controlled trials found. Dose between 33.5 to 40Gy and dose per fraction between 6.7 to 9.5Gy. Main measures were International Prostate Symptom Score (IPSS) and Expanded Prostate Cancer Index Composite – Urinary Domain (EPIC) or specific components from IPSS

PO-247 Elective pelvic irradiation in patients with biochemical recurrence following radical prostatectomy H.H. Park 1 , Y.S. Kim 1

1 Asan Medical Center- Univ of Ulsan, Radiation Oncology Department, Seoul, Korea Republic of

Purpose or Objective To investigate whether whole pelvic radiotherapy (WPRT) improves biochemical relapse-free survival (bRFS) vs. prostate bed radiotherapy (PBRT) in prostate cancer patients receiving salvage radiotherapy (SRT) after radical prostatectomy. Material and Methods Data from patients with prostate cancer who underwent SRT for biochemical recurrence between 2005 and 2012 in two academic institutions were retrospectively reviewed. Patients treated with WPRT in one hospital were compared with patients treated with PBRT in the other. Propensity scoring was performed to balance the characteristics of the different treatment groups, and bRFS was compared. Results Data from a total of 245 patients were included in the analysis (WPRT, n = 131; PBRT, n = 114). The median follow-up period was 66 months. Prior to matching, patients who received WPRT had higher pathologic Gleason scores and radiation dose to the prostate bed, as well as a higher incidence of pre-SRT PSA levels >0.5 ng/mL and lower rates of concurrent androgen- deprivation therapy. Propensity score matching balanced these characteristics and generated a cohort comprising 80 patients from each group. In the matched cohort, the 5-year bRFS of the WPRT group was significantly higher than that of the PBRT group (64.3 vs. 45.3%, p = 0.038). Multivariate analysis revealed that WPRT was an independent prognostic factor for bRFS in the propensity score-matched cohort (hazard ratio: 0.58, 95% confidence interval: 0.36–0.94). Conclusion These data suggest that, following radical prostatectomy, elective WPRT during SRT may improve bRFS compared with PBRT in selected patients. Prospective randomized studies are required to confirm this finding. stereotactic and conventionally fractionated VMAT H. Nagano 1 , H. Yokoyama 1 , M. Watanabe 1 , M. Katou 2 , H. Hashimoto 1 , T. Shimo 2 , M. Nakanishi 1 , T. Kaneko 1 , C. Isizuka 1 , H. Suzuki 1 , A. Noguchi 1 , W. Hirose 1 , K. Kobayashi 1 1 Shonan Fujisawa Tokushukai Hospital, Radiation Oncology Department, Fujisawa, Japan 2 Tokyo-West Tokushukai Hp., Radiation oncology, Tokyo, Japan Purpose or Objective It is said that prostate cancer is associated with a large dispersion in incidence and death in Asian countries, but will increase in this region in the future. Emerging technology such as volumetric-modulated arc therapy for stereotactic body radiation therapy (VMAT–SBRT) has been decreasing number of fractions and duration of treatment. Moreover rapid decline of prostate-specific antigen (PSA) has been reported. We can represent comparison of the initial half-time (within six months after treatment) of PSA between VMAT-SBRT and conventionally fractionated VMAT (CF-VMAT). Material and Methods PO-248 Comparison of initial half-life of PSA between