Open Access

ARTICLE

Risk factors for PSAbounce following radiotherapy: outcomes from a multi-modal therapy analysis

Alexandra Waters¹, Guila Delouya¹, David Donath¹, Carole Lambert¹, Sandra Larrivée², Kevin C. Zorn³, Daniel Taussky^1,2

1 DepartementofRadiationOncology,CentreHospitalierdel’UniversitédeMontréal(CHUM),HôpitalNotre-Dame,Montreal,Quebec,Canad
2 CRCHUM-Centre de recherche du Centre Hospitalier de l’Université de Montréal, Montreal, Quebec, Canad
3 Department of Urology, Centre Hospitalier de l’Université de Montréal (CHUM), Hôpital St-Luc, Montreal, Quebec, Canada
Address correspondence to Dr. Daniel Taussky, Department of Radiation Oncology, Centre hospitalier de l’Université de Montréal – Hôpital Notre-Dame, 1560 Sherbrooke St. East, Montreal, QC H2L 4M1 Canada

Canadian Journal of Urology 2014, 21(6), 7548-7553.

Abstract

Introduction: To identify risk factors for PSA bounce (PSAb) and compare characteristics of prostate cancer patients treated with brachytherapy and external beam radiotherapy (EBRT).
Materials and methods: We identified 362 patients treated for low risk prostate adenocarcinoma (D’Amico criteria) with a follow up time of at least 36 months. Patients received either: 1) EBRT 76 Gy in 38 fractions (n = 58); 2) hypofractionated EBRT, 45 Gy in 9 once-weekly fractions (n = 74); 3) seed brachytherapy (n = 230). PSAb was defined as a rise ≥ 0.2 ng/mL with subsequent return to baseline within the first 3 years after treatment. Univariate and multivariate logistic regression models were estimated to assess the association between clinical factors and occurrence of PSAb.
Results: There was no significant difference between treatment groups (p = 0.349), with an overall PSAb rate of 28.5%. Upon univariate analysis, the following were predictive of a lower PSAb rate: older age (OR = 0.96), higher PSA at diagnosis (OR = 0.87), more positive biopsy cores (OR = 0.98), and a higher Cancer of the Prostate Risk Assessment (CAPRA) score (CAPRA of 3 versus 1: OR = 0.33). Multivariate analysis confirmed the significance of fewer positive biopsy cores (OR = 0.99) and a lower CAPRA score (CAPRA 3 versus 1: OR = 0.34). These factors also predicted a shorter time to first PSAb.
Conclusions: We found comparable rates of PSAb after different regimens of radiotherapy. We hypothesize that it results from late damage to healthy prostatic tissue. This idea is supported by the fact that we found that clinical factors indicative of a lower tumor burden were predictive of a PSAb.

---

Keywords

---