ESTRO 38 Abstract book

S836 ESTRO 38

85.3% ( P = 0.681), 95.5% ( P = 0.338) and 91.7% ( P = 0.129) for the Tomotherapy group.

No. of sites of OPD

Type

of

Patient number

scan detecting OPD

Suitability for SBRT Treatment of OPD

Sites of OPD

Retroperitoneal lymph node Thoracic vertebra T1, T6 Lumbar vertebra L1 Retroperitoneal lymph node

1

1

CT

Yes

SBRT 30Gy/5#

Continuation of abiraterone + dexamethonase Continuation of abiraterone Continuation of abiraterone + prednisolone

2

3

WBDWMRI Yes

3

1

CT

Yes

No- previous EBRT

Choline PET/CT

4

1

Prostate

Switched

to

Pelvic node

lymph

Choline PET/CT

5

1

abiraterone

+

Yes

dexamethasone Stopped systemic treatment

Inguinal lymph node

6

1

CT

Yes

Conclusion OPD is prevalent in mCRPC patients on Abiraterone/ Enzalutamide. The majority of OPD occurred in non-bone metastases and a range of imaging techniques can be used to identify OPD. Most patients were asymptomatic at the time of OPD and had disease suitable for SBRT. The TRAP trial (NCT03644303) is currently testing the role of SBRT to sites of OPD in mCRPC. EP-1549 Clinical outcomes of image-guided radiotherapy in intermediate to high risk prostate cancer C. Chen 1 , H. Chuang 2 , M. Huang 3 1 Kaohsiung Medical University, Graduate Institute of Medicine- College of Medicine, Kaohsiung City, Taiwan ; 2 Kaohsiung Medical University, Faculty of Department of Public Health- College of Health Science, Kaohsiung City, Taiwan ; 3 Kaohsiung Medical University, Radiation Oncology, Kaohsiung City, Taiwan Purpose or Objective To report the long-term survival outcomes and late toxicities resulted from curative image-guided radiotherapy (IGRT) for prostate cancer patients with and without androgen deprivation therapy (ADT). Material and Methods The study included 108 patients with pathologically proven prostate adenocarcinoma who underwent IGRT between 2008 and 2014. Age ranged from 54 to 89 with a median age of 75 years. Twenty-nine patients were in the intermediate-risk group and 79 were in the high-risk group. The biochemical failure was defined by a rise of 2 ng/mL or more above the nadir PSA. The nadir was defined as lowest PSA value preceding a given threshold of 0.2 ng/mL or as absolutely lowest PSA before the transient bounce. Gastrointestinal (GI) and genitourinary (GU) toxicities were assessed and documented in agreement with the Common Toxicity Criteria Adverse Events version 3 (CTCAE v.3.0). Cox regression model and Kaplan-Meier curves were calculated, and the log-rank test was used to evaluate the differences of overall (OS), biochemical failure free (BFFS), disease free (DFS), locoregional failure free (LRFS) and distant metastases-failure free (DMFS) rates between two different modalities of radiotherapy. Results Among 108 patients, 32 patients (29.6%) were treated with RapidArc and 76 patients with Helical Tomotherapy. The mean radiation dose was 75 Gy. The median follow-up was 4.43 years (range, 417-3330 days). Two patients (2.8%, 2/72) in the EBRT-ADT group developed late GI complication 20 months after EBRT. There was no late GU complication. All patients tolerated the IGRT without any interruption. The 5-year OS, DFS, BFFS, LRFFS and DMFFS rates were 83.7%, 81.3%, 86.0%, 92.4% and 100.0% for the RapidArc group while 89.2% ( P = 0.635), 80.1% ( P = 0.747),

Conclusion There exists no statistically significant difference in the rates of locoregional recurrence, distant metastasis, biochemical control and overall survival when comparing RapidArc with Tomotherapy. IGRT was well tolerated with small late GU and GI toxicity. EP-1550 Give-me-five trial: toxicity assessment in ultra-hypofractionated prostate cancer radiotherapy D. Ciardo 1 , G. Marvaso 1 , S. Gandini 2 , M. Mambretti 1 , C. Fodor 1 , D. Zerini 1 , S. Volpe 1,3 , G. Riva 1,3 , D.P. Rojas 1 , G. Petralia 4 , R. Cambria 5 , R. Orecchia 6 , B.A. Jereczek- Fossa 1,3 1 IEO- European Institute of Oncology IRCCS, Department of Radiation Oncology, Milan, Italy ; 2 IEO- European Institute of Oncology IRCCS, Division of Epidemiology and Biostatistics, Milan, Italy ; 3 University of Milan, Department of Oncology and Hemato-Oncology, Milan, Italy ; 4 IEO- European Institute of Oncology IRCCS, Department of Radiology, Milan, Italy ; 5 IEO- European Institute of Oncology IRCCS, Unit of Medical Physics, Milan, Italy ; 6 IEO- European Institute of Oncology IRCCS, Scientific Direction, Milan, Italy Purpose or Objective To evaluate genitourinary (GU) and gastrointestinal (GI) toxicity after ultra-hypofractionated prostate cancer (PCa) radiotherapy. Material and Methods As a part of the prospective phase II Give-me-five trial, 65 PCa patients underwent volumetric modulated arc therapy with simultaneous integrated boost to the dominant