Nadir PSA in prostate brachytherapy: relationship with biochemical control and clinical results.
SILVIA RODRIGUEZ VILLALBA,
Spain
PO-2199
Abstract
Nadir PSA in prostate brachytherapy: relationship with biochemical control and clinical results.
Authors: SILVIA RODRIGUEZ VILLALBA1, DIANA GUEVARA BARRERA1, JOSE PÉREZ-CALATAYUD1,2, FRANCISCO BLAZQUEZ MOLINA1, MANUEL SANTOS ORTEGA1
1Hospital Clinica Benidorm, Radiation Oncology Department, Benidorm, Spain; 2La Fe University and Polytechnic Hospital, Radiation Oncology Department, Valencia, Spain
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Purpose or Objective
To evaluate nadir prostate-specific antigen (nPSA) and its relationship with biochemical failure (BF), local failure (LF), lymph node failure (LNF) and distant metastases (DM) in prostate cancer (PC) patients, treated with LDR and HDR brachytherapy (BT).
Material and Methods
We retrospectively analyzed 140 patients diagnosed PC treated between 2005-2019 with exclusive BT. Sixty four patients treated with LDR (160 Gy) and 76 with HDR (2 implants of 13.5 Gy each). 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 BT contouring plus and the technical process, maintain a high degree of homogeneity.
Results
Median age 69 years (46-84). 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 70 months (5-202). Median PSA at diagnostic 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. Ninety-five patients (68%) were include in group 1, 27 patients (19%) in group 2, 8 patients (6%) in group 3 and 9 (7%) in group 4.
Median nPSA group 1 was 0.08 ± 0.63 ng/ml, 0.30 ± 0.06 ng/ml in group 2, 0.57 ± 0.14 ng/ml in group 3 and 1.45 ± 0.48 ng/ml in group 4. Median time to reach nadir was 30 months (3-108) in group 1, 24 months (3-48) in group 2, 21 months (9-36) in group 3 and 12 months (3-36) in group 4.
BF was observed in 4 patients (4%) of group 1 (3 patients with exclusively LF and one with LF and LNF), 4 patients (15%) of group 2 (3 LF), 4 patients (50%) in group 3 (1 LF) and 7 patients (78%) in group 4 (5 FL, 7 LNF and 6 DM). Median time to FB 73 months (21-202) in group 1, 55 months (14-164) in group 2, 52 months (54-147) in group 3 and 39 months (7-79) in group 4.
Conclusion
The nPSA categories provide prognostic information that identify the patients at increased risk of FB, LF, LNF and DM. Reach low nadir values at a set time point post-BT predicts improved clinical outcomes. Evaluation of nPSA in BT exclusively treatments in low risk and intermediate risk PC provided a very useful tool in the follow-up of these group of patients, in order to establish early rescues strategies.