ESTRO 2024 - Abstract Book

S422

Brachytherapy - Urology

ESTRO 2024

2175

Mini-Oral

SBRT vs SBRT + HDR-boost: a prospective comparative analysis of toxicity, QoL and disease control.

Laura Zaragoza, David Buchser, Uxue Ruiz, Rosa Hernandez, Carlos Mascarell, Jon Cacicedo, Alfonso Gomez Iturriaga

Cruces Hospital, Radiation Oncology, Bilbao, Spain

Purpose/Objective:

To compare acute toxicity, Prostate Specific- Antigen (PSA) Kinetics, disease control and impact on Quality of life (QOL) between two distinct treatment modalities for localized prostate cancer from two prospective series: exclusive SBRT and a combination of HDR-Brachytherapy boost (HDR-BT) and SBRT.

Material/Methods:

A total of 239 patients with localized prostate cancer were enrolled in two different prospective series to receive 2 different treatment modalities, either a combination of HDR- BT 15Gy followed by 5 daily fractions of 5Gy SBRT or SBRT 36.25 Gy or 40 Gy (depending on risk group) in 5 every other day (EOD) fractions. Short or long-term androgen deprivation therapy (ADT) was prescribed according to risk stratification. Image-guided RT through intrafraction fiducial marker monitoring was used for SBRT. All patients underwent a diagnostic mpMRI of the prostate. Acute (first 6 months after treatment completion) genito-urinary (GU) and gastro-intestinal (GI) toxicity were evaluated based on CTCAE v5. Patient QoL was assessed with Patient-reported outcome measures (PROMS) as per ICHOM (international consortium for health outcomes measurement) methodology through EPIC and EORTC QLQ PR25 questionnaires. A change of > 0.5 standard deviation from baseline values was considered clinically relevant.

PSA kinetics in patients without ADT were evaluated.

The proportion of patients showing biochemical failure (PSA NADIR + 2 ng/mL), metastatic failure or death from prostate cancer was studied.

Results:

Table 1 shows clinical relevant characteristics of the patients. Among the 239 patients who completed the treatment, 146 received HDR-BT and SBRT while the remaining 93 underwent SBRT (66 patients received 36.25Gy and 27 patients received 40Gy). Median follow up was 28.5 (IQ range 3-52) and 22.6 months (IQ range 3-44) respectively.

Median age was 77 years in both cohorts, with an initial median PSA of 7.4 and 7 ng/ml, median IPSS score of 6 and 7, median MRI volume of 36 cc and 43 cc respectively.