ESTRO 38 Abstract book

S451 ESTRO 38

3.

Comparison : a table listing pros and cons of each treatment side-by-side. My knowledge : Ten true/false questions to confirm the patient’s understanding. My preferences : 16 values clarification questions about treatment experience, quality of life, and uncertainty. My comparison : four questions asking the patient to select treatment aspects that are least desirable. My results : a tabular overview of the values clarification. This can be printed for use in the consultation to guide the SDM talk in accordance with patient values.

4.

5.

6.

7.

Conclusion User-centered design provided valuable insights into PDA requirements but resulted in a time-consuming process and a diverse range of perspectives that were challenging to integrate. The PDA is currently being evaluated in a clinical trial (NCT03278197). PO-0856 Metastasis-directed therapy for oligoprogressive castration refractory prostate cancer C. Berghen 1 , S. Joniau 2 , P. Ost 3 , K. Poels 1 , W. Everaerts 2 , K. Haustermans 1 , G. De Meerleer 1 1 University Hospital of Leuven, Radiation Oncology, Leuven, Belgium ; 2 University Hospital of Leuven, Urology, Leuven, Belgium ; 3 University Hospital of Ghent, Radiation Oncology, Ghent, Belgium Purpose or Objective In metastatic castration refractory prostate cancer (mCRPC) state-of-the-art treatment consists of a systemic treatment with second-line hormones, chemotherapy or bone seeking agent in addition to palliative androgen deprivation therapy (pADT). Clinical progression is the signal to switch to next-line systemic treatment (NEST). A subgroup of these progressive patients shows oligoprogression, defined as the progression of a limited number of metastatic spots while the majority of metastases are controlled by ongoing systemic therapy. We hypothesized that metastasis directed therapy (MDT) against these oligoprogressive lesions might defer the need for NEST. Therefore, we performed this We analyzed the outcome of patients who were treated with MDT for mCRPC oligoprogressive disease, defined as either the progression of ≤3 existing oligometastatic sites and/or the appearance of ≤3 new metastasis and/or local recurrence. In total, the number of progressive/new lesions was ≤3. All patients were under systemic therapy with pADT whether or not combined with second-line systemic treatment. The time frame of the study was from 1/2012 until 3/2018. Primary endpoint was NEST-free survival (NEST-FS). Secondary endpoints were progression- free survival (PFS) and toxicity scoring. Results A total of 35 cases of oligoprogression were included who received MDT consisting of SBRT (n=22), metastasectomy (n=2), or local treatment with more conventionally fractionated radiotherapy (n=11). A total of 51% in the MDT-group had upfront metastatic disease, from which 61% had upfront oligometastatic disease. At the time of oligoprogression the majority had bone lesions (69%). Others had nodal disease or a combination of both or local recurrence. There were no patients with oligoprogressive visceral metastasis. Most patients were on systemic treatment with pADT only. The median follow-up time was 30 months (IQR 9-42). There was a median NEST-free survival (NEST-FS) of 16 months (CI 95% 12-31) and PFS of 12 months (CI 95% 7-18). SBRT or surgery-related toxicity was minor, with limited grade 1 and 2 toxicity and only one patient experiencing acute grade 3 toxicity after treatment for local relapse in the prostate. retrospective analysis. Material and Methods

Conclusion Our data demonstrate an important deferral of NEST with a median NEST-FS of 16 months in 35 cases of patients treated with MDT. These data are unique and may induce a paradigm shift in the treatment of these patients. Prospective clinical trials are warranted to further define the patient characteristics and treatment outcomes. PO-0857 MRI-derived radiomics to select patients with high-risk prostate cancer for adjuvant radiotherapy V. Bourbonne 1 , M. Vallières 2 , F. Lucia 1 , G. Fournier 2,3 , A. Valéri 2,3 , D. Visvikis 2 , V. Tissot 4 , O. Pradier 1,2 , M. Hatt 2 , U. Schick 1,2 1 CHRU Brest, Radiation Oncology, Brest, France ; 2 Université de Bretagne Occidentale, LaTIM UMR 1101 INSERM, Brest, France ; 3 CHRU Brest, Urology Unit, Brest, France ; 4 CHRU Brest, Radiology, Brest, France Purpose or Objective Radical prostatectomy (RP) is one of the treatments of choice for patients with prostate cancer (PCa) but biochemical recurrence (BCR) after RP occurs in 50% of patients, particularly in those who harbor high risk features like locally advanced disease (T3-4), positive margins (R1) or high Gleason score. Adjuvant radiotherapy