ESTRO 2024 - Abstract Book

S399

Brachytherapy - Urology

ESTRO 2024

Median age at diagnosis of the primary PCa 64,5 years (range 53-73 y) and in the recurrence 72,5 years (range 63-80 y). Patients were considered for focal salvage if they had no evidence of distant metastatic disease on CT scan, bone scan and mpMRI, and in 8 patients (50%) choline PET. PSMA PET was not used in the evaluation of these patients. Eight patients have received primary external beam radiotherapy (EBRT. 50%), 8 LDR BT (37,5%) and 2 a combined treatment of EBRT + LDRBT. 12,5%). Median time from previous radiotherapy treatment was 83 months (20-155 m). Biochemical failure following initial RT and after BT was defined using the Phoenix criteria. Histologic recurrence was confirmed in 12 patients (75%), six of them with Gleason 8 or 9. The pre-BT median PSA was 3,71 ng/ml (range 0,28-9,43 ng/ml). Adjuvant androgen deprivation therapy (ADT) was used in 10 cases (62,5%). Three patients (19%) were salvaged with LDR and 13 (81%) with HDR. The prescription dose was to the whole prostate in 14 patients (87,5%) and in 2 cases to the affected lobe (12,5%). Six cases (37,5%) were classified as castration-resistant prostate cancer (CRPC) in at the time of salvage. There are not gastrointestinal (GI) acute/late G3 toxicities. There was 1 patient with an intraprostatic abscess requiring surgical drainage. The most common acute genitourinary (GU) toxicity was frequency, dysuria and urgency grade 2 (50%). Acute urinary retention was observed in 2 patients (19%). Chronic cystitis grade 2 was 37,5%, treated with medical management. Late grade 3 GU toxicity was seen in 19% (2 cystitis, 1 hematuria). Biochemical failure was evidenced in 10 patients (62,5%) in a median time of 11 months (5-68m). Two patients had local persistence (12,5%), 1 a recurrence in seminal vesicle (6,25 %) and 7 distant failures (43,75%). All were treated with ADT, including second-generation antiandrogens in 5 of them. Median follow-up after salvage brachytherapy was 71,5 months (20-165 m). In the last follow-up (October 2023) 3 patients (19%) are alive without evidence of tumor, 4 patients (25%) are alive with ADT treatment, 3 (19%) have had intercurrent deaths and 6 (37,5%) have died because of systemic progression.

Conclusion:

Salvage brachytherapy in recurrent prostate carcinoma is technically possible but not in all cases indicated. Optimal patient selection remains critical. Despite of it, disease control is poor in our series, with a high percentage of genitourinary toxicity . It is important to balance expected treatment effectiveness and future quality of life in these patients, who have significantly lower survival rates. More imaging and radiobiological studies are required in order to achieve greater control of the disease while minimizing toxicity.

Keywords: Prostate, Salvage, Brachytherapy

References:

1. Henry A, Pieters BR, André Siebert F, Hoskin P; UROGEC group of GEC ESTRO with endorsement by the European Association of Urology. GEC-ESTRO ACROP prostate brachytherapy guidelines. Radiother Oncol. 2022 Feb;167: 244 251.

2. Ash D, Flynn A, Battermann J et al. ESTRO/EAU/EORTC recommendations on permanent seed implantation for localized prostate cancer. Radiother Oncol 2000; 57: 315-321.

3. Hoskin PJ, Colombo A, Henry A et al. GEC/ESTRO recommendations on high dose rate afterloading brachytherapy for localised prostate cancer: an update. Radiother Oncol 2013; 107: 325-332.