ESTRO 2023 - Abstract Book

S1222

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ESTRO 2023

EM tracking device consisted of an Foley catheter with an integrated transmitter. Patients were simulated and treated with a filled bladder and an empty rectum. Setup accuracy was verified with a ConeBeam-CT (CBCT) matching on soft tissues before each session. The EM gating device consisted of a Foley catheter with an integrated EM transmitter. This transmitter is connected to the treatment table, thus allowing an online monitoring of the prostate displacements during the whole procedure (CBCT acquisition + treatment delivery). Treatment was manually interrupted when the signals exceeded a 2 mm threshold in any of the three spatial directions. A new CBCT was performed if the offset was transient (>20 secs.). Results Median age was 73.4 years (range : 60.7-84.6). Four, 8, 6 and 2 patients were classified as ISUP 1, 2, 3 and 4, respectively. Seven patients received concomitant and adjuvant androgen deprivation therapy. Median and mean fraction durations were 10m31s and 12m44s (range: 6m36s - 65m28s), respectively, and 95% of the fractions were delivered with a maximum whole treatment time of 27m48s. During the treatment, the prostate was outside the CTV-to-PTV margin (2mm) for 11.2%, 8.9% and 3.9% of the treatment time, in the vertical, longitudinal and lateral direction, respectively, thus needing to stop the delivery +/- a reacquisition of the CBCT. Median followup was 4 months (range: 0.8 – 8.3). Table 1 shows acute and late (only for patients with at least 3 months of followup, N = 14) toxicity.

Acute Toxicity

G0 G1 G2 G3 G4 19 0 1 0 0

Proctitis Diarrhoea

20 0 0 0 0 Obstructive Urinary Symptoms 17 1 2 0 0 Cystitis 4 8 8 0 0 Late Toxicity G0 G1 G2 G3 G4 Proctitis 13 1 0 0 0 Diarrhoea 14 0 0 0 0 Obstructive Urinary Symptoms 11 1 2 0 0 Cystitis 11 2 1 0 0

Noteworthy, the G1-2 acute cystitis was related to the presence of the catheter. None of the patients reported a G2 toxicity at the first followup visit 30-40 days after SBRT. At followup visit 30-40 days after SBRT, and all but one of them presented a biochemical response (median: 75%; range : 43 – 100). One patient presented a PSA bounche 1 month after SBRT, but we observed a normalisation of his PSA 3 months later. All the patients are alive and disease-free at the moment of this analysis. Conclusion EM trasmitter-based gating for dose-escalated prostate SBRT successfully implemented in our department for intrafraction motion management during dose-escalated prostate SBRT. Very early clinical data are encouraging. Longer follow-up is needed and is ongoing

PO-1504 Quality of life in oligometastatic prostate cancer patients treated with SBRT using EORTC form

J. Ma 1 , P. Rogowski 2 , C. Trapp 1 , N. Schmidt-Hegemann 1 , C. Belka 1 , M. Li 1

1 University Hospital LMU , Radiation Oncology, munchen, Germany; 2 University Hospital LMU , Radiation Oncology, Munich, Germany Purpose or Objective To evaluate the quality of life in patients with oligometastatic prostate cancer treated with stereotactic ablative body radiotherapy (SBRT) using EORTC QLQ-C30 and -PR25 questionnaires Materials and Methods In this prospective study, 73 consecutive patients receiving SBRT to 110 metastatic lesions (91 bones, 14 lymph nodes, 5 local recurrences) were included from Sep. 2019 to Oct. 2022. 105 lesions were treated with 5x6Gy stereotactic ablative body radiotherapy, three lesions with 10x4 Gy, 2 lesions with 5x5 Gy, respectively. Each patient was asked to fulfil EORTC QLQ-C30 and -PR25 questionnaires before RT, at RT end, 3 months 1 and 2 years after RT, respectively. Diverse functional scores (100 for the best and 0 for the worst functioning) and symptom scores (100 for the strongest and 0 for no symptoms) were calculated at each time point. Results In general, QLQ-C30 functional scores before RT were satisfactory and symptom scores were sparse. QLQ-C30 symptom scores before RT were also sparse except urinary symptoms. The sexual functional scores were modest, probably due to the old age (median 74). At RT end, there was a slight decline of role functional scores and a remarkable increase of symptom scores in terms of fatigue, loss of appetite and incontinence aid. The decline of other functional scores were moderate. The increase of other symptom scores were also moderate except insomnia and diarrhoea, which even presented a decrease. Three months after RT, physical and sexual function almost recovered to their baseline level and sexual activity recovered only partially, while role function remained stable. Interestingly, general healthy status, cognitive, emotional and social