HDR-BT and SBRT in prostate cancer: results from a prospective phase II trial NCT04523896
David Buchser Garcia,
Spain
OC-0626
Abstract
HDR-BT and SBRT in prostate cancer: results from a prospective phase II trial NCT04523896
Authors: David Buchser Garcia1, Ane Bilbao1, Marina Marban1, Jon Cacicedo1, Fernando Perez2, Itziar Valverde2, Jose Maria Espinosa2, Borja Santos3, Francisco Casquero1, Alfonso Gomez-Iturriaga1
1Hospital Universitario Cruces, Radiation Oncology, Barakaldo, Spain; 2Hospital Universitario Cruces, Radiation Physics, Barakaldo, Spain; 3Biocruces Health Research Institute, Epidemiology and statistics, Barakaldo, Spain
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Purpose or Objective
To report late toxicity, disease control and impact on QoL in patients treated with a combination of HDR prostate brachytherapy and prostate SBRT for intermediate and high-risk prostate cancer in a phase II prospective trial.
Material and Methods
In this prospective phase II trial, a total of 72 patients with intermediate (IR) and high risk (HR) prostate cancer were recruited to receive a combination of real time HDR-BT 15 Gy followed by SBRT to the prostate: 5 fractions of 5 Gy each delivered in consecutive days with or without short or long-term androgen deprivation therapy (ADT). Image-guided RT through intrafraction fiducial marker monitoring was used for SBRT. All patients underwent a diagnostic mpMRI of the prostate.
Genito-urinary (GU) and gastro-intestinal (GI) toxicity was assessed according to CTCAE v5. Patient QoL was evaluated through ICHOM (international consortium for health outcomes measurement) methodology with EPIC and EORTC QLQ-PR25 questionnaires. A decreased of > 0.5 standard deviation of baseline values was considered clinically relevant.
The proportion of patients showing biochemical failure (PSA NADIR + 2 ng/mL), metastatic failure or death from prostate cancer was studied.
Results
Sixty-three patients (NCCN 56,9% IR and 43,1% HR) completed treatment and reached at least 12 months of follow-up (FU) at the time of the current analysis. Median FU was 29 months (IQ range 20-36). Median age was 75 years, median PSA before treatment was 7.1 ng/mL (5.6-11.2) and median volume of the prostate was 33 cc (27-43.5).
Short-term ADT was administered to 22,2% of patients whereas 37,5% received long-term ADT, the rest of the patients did not receive hormonal therapy.
No severe (i.e. G3-4) acute or late events were recorded. The cumulative incidence of acute G2 GU and GI events were 14.7% and 1.6% respectively. The most common acute GU symptom was dysuria whereas the most common acute GI event was proctitis. The cumulative incidence of late G2 GU events was 12.7% whereas no G2 late GI event was observed. The most common late GU symptom was nocturia.
No significant decline in patient QoL was observed in any of the domains studied (urinary, bowel, sexual and hormonal).
Only 1.6% of patients (1 patient) had a biochemical failure. No metastatic failures or deaths attributable to prostate cancer were recorded. Median PSA nadir was 0.04 ng/mL (IQ range 0.02-0.28).
Conclusion
This prospective phase II trial confirms that the combination of 15Gy HDR prostate brachytherapy and prostate SBRT (25 Gy in 5 daily fractions) is a well-tolerated scheme, and no severe adverse events were recorded. Moreover, patient reported outcomes confirm these results, we could not find a significant decline in any domain from baseline values.
This approach shows promising disease control data that warrants further investigation.