ESTRO 2024 - Abstract Book

S400

Brachytherapy - Urology

ESTRO 2024

559

Digital Poster

PSA outcomes after LDR/HDR brachytherapy in LR and IR prostate cancer: a predictor of response

Silvia Rodríguez Villalba 1 , Diana Guevara Barrera 1 , Luis Suso Martí 2 , Enrique Sanchís Sanchís 2 , Jose Pérez-Calatayud 3 , Maria Jose Pérez Calatayud 3 , Manuel Santos Ortega 1 1 Hospital Clínica Benidorm, Radiotherapy Department, Benidorm, Spain. 2 Universidad de Valencia, EXINH-RG. Physiotherapy Department, Valencia, Spain. 3 Hospital Universitario y Politécnico la Fe, Radiotherapy Department, Valencia, Spain

Purpose/Objective:

To evaluate nadir prostate-specific antigen (nPSA) and its relationship with biochemical failure (BF) in low risk (LR) and favorable intermediate risk (FIR) prostate cancer (PC) patients, treated with LDR and HDR brachytherapy (BT).

Material/Methods:

We retrospectively analyzed 140 patients diagnosed of PC treated between 2005-2019 with exclusive BT: LDR (160 Gy) and HDR (2 implants of 13.5 Gy each separated 10 days). nPSA was grouped into 4 categories: PSA 0.2 ng/mL (group 1), >0.2 to 0.5 ng/mL (group 2), >0.5 to 1.0 ng/mL (group 3) and >1.0 ng/m (group 4). BF was determined using the Phoenix definition (nadir +2). All of the treatments have been done by the same Radiation Oncologist. In addition, the Physicist team followed a strict protocol to assure uniformity. It guarantees both BT contouring, and the technical process, maintain a high degree of homogeneity. Statistics Package for Social Science (SPSS 24.00, IBM Inc., EE.UU.) was used for analysis.

Results:

Median age 69 years (46-84). Sixty-four (46%) patients treated with LDR and 76 (54%) with HDR. Seventy-seven patients received androgen deprivation therapy, 33% as neoadjuvant. LDR: 100% low risk. HDR: 44% low risk and 56% favorable intermediate risk. Median follow-up was 80 months (5-202). Median PSA at diagnosis 7.12 ± 2.96 ng/ml. Median D90 LDR 180.5 ± 9.6 Gy. Median D90 first implant HDR 14.49± 0.3 Gy. Median D90 second implant HDR 14,50 ± 0,30 Gy. One hundred four patients (74%) were included in group 1, 19 patients (14%) in group 2, 8 patients (6%) in group 3 and 9 (6%) in group 4. Median nPSA group 1 was 0.05 ± 0.061 ng/ml, 0.29 ± 0.07 ng/ml in group 2, 0.54 ± 0.14 ng/ml in group 3 and 1.45 ± 0.48 ng/ml in group 4. Median time to reach nadir was 36 months (3-144) in group 1, 18 months (6-48) in group 2, 21 months (9-36) in group 3 and 12 months (3-36) in group 4. The actuarial biochemical failure-free survival (BFFS) was 99% and 91% at 5 and 10 years respectively in group 1, 86 % and 60% at 5 and 10 years in group 2, 73% and 55% at 5 and 10 years respectively in group 3 and 22% at 5 and 10 years in group 4 (p< 0,001).