ESTRO 36 Abstract Book

S696 ESTRO 36 2017 _______________________________________________________________________________________________

2 Good Samaritan Hospital Medical Center, Urology, West Islip, USA Purpose or Objective Radiation technique for prostate cancer has continuously evolved over the past several decades. We describe the effect of utilizing prostate MRI, implementation of strict dose-volume constraints and reducing dose to the uninvolved prostate to <80 Gy on radiation dosimetry and patient outcomes. Material and Methods From 1/10 to 4/12, 48 consecutive patients were treated with standard prostate IMRT (S-IMRT) to 81 Gy. From 5/12 to 4/15, 50 consecutive patients were treated with modern IMRT (M-IMRT) treating the entire prostate to 75.6 to 79.2 Gy while using prostate MRI fusion, dose volume constraints prioritizing normal tissue avoidance above PTV coverage and boosting any dominant intraprostatic masses to 79.2 to 81 Gy. We compared rectal Dmax, V75, V60, V65, V50 and bladder Dmax, V75, V70 and V65 and acute and late toxicity between the S-IMRT and M-IMRT groups. Results The median follow-up for the S-IMRT group was 61 months compared to 26 months (p<0.001). Patient characteristics were well matched except for a higher percentage of NCCN low risk patients in the S-IMRT group. M-IMRT resulted in a significant reduction in median rectal Dmax, rectal V75, rectal V70, rectal V65, bladder Dmax, bladder V75, bladder V70 and bladder V65 (p<0.01 for all). There was no significant difference in rectal V50. There were no significant differences in acute GI or GU toxicity. The 2- year rate of late grade >=2 rectal bleeding was 13% with S-IMRT vs. 3% with M-IMRT (p=0.03). The 2-year rate of late grade >=2 genitourinary toxicity was 11% for S-IMRT vs. 5% for M-IMRT (p=0.21). There were no differences in biochemical control or overall survival. Conclusion While modern MR-guided IMRT for prostate cancer requires increased resources, there is a clear benefit in terms of reduced toxicity without sacrificing disease control implying improved therapeutic ratio. EP-1312 Long terms outcome in prostate cancer with image guided and intensity modulated radiation therapy. C. Salas 1 , L. Gutiérrez 1 , S. Garduño 1 , M. Macias 1 , L. Ingunza 1 , I. Villanego 1 , V. Díaz 1 , E. Gonzalez 1 , L. Díaz 1 , A. Ureña 2 , L. Quiñones 2 , J. Jaén 1 1 Hospital Universitario Puerta del Mar, Comprehensive Care Department Cancer- Radiation Oncology Service- University Hospital Puerta del Mar, Cadiz, Spain 2 Hospital Universitario Puerta del Mar, Clinical management unit Hospital Radiophysics and Radiation Protection- University Hospital Puerta del Mar, Cadiz, Spain Purpose or Objective The use of gold seeds as radiopaque fiducials (MF) intraprostatic indirectly to locate and visualize the prostate treatment with RT dose escalation, it`s called Image Guided Radiation Therapy (IGRT). Combined with Intensity Modulated Radiation Therapy (IMRT), we increased technical precision and high dose to the target volume with dose limiting to the rectum and bladder (OAR). To report long-term tumor control and late gastrointestinal (GI) and genitourinary (GU) toxicity rates in low, intermediate and high risk prostate cancer (PC) patients, treated with IGRT with fiducial markers and IMRT. Material and Methods Between January 2012 and April 2015, 104 men with PC (T1c-T3a), prostate-specific antigen [PSA] 5-20 ng/dL, or Gleason score [GS] 6 and 7, received normofractionated external radiation therapy and IGRT. 30% received short

androgen deprivation (AD) and 70% without AD. The dose was 76 Gy at least 98% the planning target volume in 38 (2 Gy) daily fractions, using IMRT with 6 Mv. Daily image guidance of the prostate was performed with two Electronic Portal Imaging Device (EPID) (antero-posterior and lateral) by automatic matching of the four fiducial markers, in ONCOR. Planning target volume was defined as prostate ± seminals vesicles with 7-mm. margin, except 5-mm. in rectal. Constraints: rectum V70<10%, V50<50%; bladder V70<35%, V65<50%. Biochemical failure was defined according to Phoenix criteria (nadir + 2ng/dL). Follow-up was every 6 months during first 3 years and annually thereafter. GI and GU toxicity were prospectively assessed and scored according to the Radiation Therapy Oncology Group (RTOG). Results Median follow-up was 43 months (range 36-48). Median age was 69 years (range 52-79); 12% had a Gleason score (GS) of 7 and 88% GS of 6. Median initial PSA was 7.8 ng/dL (range 3.6 -19 ng/mL) , 79% had low , 15% intermediate and 6% high risk. One patient developed biochemical failure; one patient developed bone metastases, 3 patients died from other causes. Four-year actuarial biochemical recurrence-free, cancer-specific, and overall survival rates were 98%, 98%, and 95%, respectively. The worst grade 2-3 GU or GI late toxicity was 3% and 1%, respectively. At the last follow-up, grade 2-3 late GI and GU toxicity rates were 1 % for both groups. No grade 4 or 5 late toxicity occurred. Conclusion IGRT with intraprostatic fiducial markers and IMRT for PSA< 20 ng/ml prostate cancer, is associated with excellent long-term biochemical control with very low late GU and GI toxicity. EP-1313 18 F NaF PET use in prostate cancer staging in a single centre 2013-2016: retrospective review M. Higgins 1 , J. Murphy 2 , K. Nugent 3 , K. O'Regan 2 , P. Kelly 3 1 Cork University Hospital- Cork- Ireland, Radiation Oncology, Dublin, Ireland 2 Cork University Hospital- Cork- Ireland, Radiology, Cork, Ireland 3 Cork University Hospital- Cork- Ireland, Radiation Oncology, Cork, Ireland Purpose or Objective NaF PET/CT has been in use at Cork University Hospital in staging prostate cancer since March 2013. Its advantage is increased sensitivity and specificity in detecting bone metastases compared with Tc 99 bone scintigraphy. The detection of occult bone metastases may result in changes to treatment recommendations with potentially significant impact on patient quality of life. Our aim was to assess the impact of NaF PET CT on treatment decisions in our regional cancer centre. Material and Methods A retrospective analysis was performed of NaF PET/CTs undertaken at the PET/CT Unit at CUH from March 2013 to March 2016. Imaging studies on the Picture Archiving and Communication System (PACS) as well as electronic and paper-based patient records were reviewed Results 43 NaF PET/CTs were performed on 39 men with prostate cancer in CUH between 20 th March 2013 and 31 st March 2016. Indications for NaF PET/CT included: 1.Initial staging of newly diagnosed prostate cancer, mainly with high grade disease (Gleason 8-10) or discordant standard staging studies (Tc99 bone scan, MRI, CT) [Group 1] 2. Prior treatment and suspected first osseous metastasis {Group 2] 3. Suspected progression of osseous metastatic disease with negative/indeterminate standard imaging[Group 3]