Efficacy and Safety of Simultaneous Integrated Boost Radiotherapy in HR/VHR Prostate Cancer With EPLNI (SIB-VMAT)

Prospective Evaluation of Efficacy and Safety of Simultaneous Integrated Boost (SIB-VMAT) Radiotherapy in HR/VHR Prostate Cancer With EPLNI

The aim of this study is to evaluate the efficacy and safety of hypofractionated simultaneous integrated boost volumetric arc radiation therapy (SIB - VMAT) for high-risk and very high-risk localized prostate cancer in terms of:

1. Acute and late gastrointestinal and genitourinary toxicities.
2. Evaluate the efficacy in terms of early bPFS.
3. Dosimetric evaluation in terms of target coverage and organs at risk sparing

Study Overview

• Status: Recruiting
• Conditions: Prostate Cancer Patients Treated by Radiotherapy
• Intervention / Treatment: Radiation: Simultaneous Integrated Boost Volumetric Modulated Arc Therapy (SIB-VMAT)

Detailed Description

Background:

Despite the overwhelming success of hypofractionation for prostate-only radiotherapy, a substantial gap in high-level evidence exists regarding its application to elective pelvic lymph node irradiation. The pivotal trials establishing the 60 Gy/20 fraction standard (such as CHHiP and PROFIT) largely excluded extensive whole pelvic nodal irradiation. Consequently, there remains a lack of definitive, prospective data validating the safety and efficacy of a hypofractionated Simultaneous Integrated Boost (SIB) technique that concurrently delivers 44 Gy to the pelvic lymph nodes and 60 Gy to the prostate over 20 fractions. While modern image-guided, Volumetric Modulated Arc Therapy (VMAT) provides the dosimetric conformity required to spare organs at risk (OARs) such as the bladder and bowel, clinical confirmation of acute and late toxicities in the context of wide-field pelvic irradiation remains paramount.

Therefore, this prospective, single-arm trial is designed to address this critical evidence gap. By rigorously evaluating the GI and GU toxicity profiles and early biochemical control, this study seeks to validate the 4-week SIB protocol as a safe, efficacious, and resource-efficient standard of care for high-risk prostate cancer requiring elective pelvic nodal irradiation.

Objectives:

To evaluate the safety of hypofractionated SIB - VMAT radiation therapy in terms of acute and late GI and GU toxicities, and also evaluate the efficacy in terms of early bPFS, and lastly, dosimetric evaluation in terms of target coverage and OAR sparing Study Arms Single arm Population: Histologically confirmed localized prostatic adenocarcinoma with high and very high risk groups.

Primary Endpoint: Acute and late GIT & GU toxicities (according to CTCAE & RTOG).

Secondary Endpoints:

1. To evaluate early biochemical control (serum PSA) at 6 and 12 months.
2. To perform a dosimetric analysis of target coverage and of organs at risk (OARs) dose contains.

Significance α = 0.05 two-sided; power = 80%; minimum detectable HR = 0.65 Duration 12 months total (from IRB approval to submission of the manuscript).

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Mohamed Alhefny, MD; Phone Number: +201228169673; Email: Alhefny@med.asu.edu.eg
• Study Contact Backup: Name: Ahmed Sohaib, MD; Phone Number: +201060406063; Email: dr.ahmed.sohaib@gmail.com

Study Locations

• Egypt
  • Cairo, Egypt
    • Recruiting
    • Faculty of Medicine, Ain Shams University
    • Contact: Mohamed Alhefny Almashtouly, MD; Phone Number: +201228169673; Email: Alhefny@med.asu.edu.eg
  • Shibīn al Kawm, Egypt
    • Recruiting
    • Faculty of Medicine - Menoufia University
    • Contact: Ahmed Sohaib, MD; Phone Number: +201060406063; Email: dr.ahmed.sohaib@gmail.com
  • Sohag, Egypt
    • Recruiting
    • Faculty of Medicine - Sohag University
    • Contact: Alshaymaa Abdelghaffar, MD; Phone Number: +201006828975; Email: alshimaaahmed@med.sohag.edu.eg

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Histologically confirmed adenocarcinoma of the prostate.
• Classification as High-Risk (HR) or Very High-Risk (VHR) per NCCN guidelines (e.g., T3a+, PSA > 20 ng/mL, or Gleason Score 8-10).
• Adequate baseline urinary function (IPSS \le 20).
• Multiparametric MRI of the prostate.
• CT Chest, Abdomen, and Pelvis.
• Bone scan
• Optional: PSMA-PET/CT to definitively exclude distant metastases (M1) and provide high-fidelity nodal assessment prior to treatment planning.

Exclusion Criteria:

• Prior pelvic radiotherapy.
• History of Inflammatory Bowel Disease (IBD) or active severe proctitis.
• Presence of distant metastases.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: SIB-VMAT radiation therapy; Patients with histopathologically confirmed prostatic adenocarcinoma staged as high-risk / very high-risk localized disease will receive radiotherapy using Simultaneous Integrated Boost Volumetric Modulated Arc Therapy (SIB-VMAT) over a total duration of 4 weeks (20 consecutive working days). Target volumes: PTV-1 (PTV 44 Gy) Prostate + Pelvic Lymph Node PTV (PLNI): 44 Gy delivered in 20 fractions (2.2 Gy/fraction), including the internal iliac, external iliac, obturator, presacral nodal stations, whole prostate, and SV. PTV-2 (PTV 60 GY): 60 Gy delivered in 20 fractions (3 Gy/fraction), including the whole prostate and the base of the SV (proximal 1 cm). Systemic Therapy is allowed during the study when indicated. Patients will receive long-term Androgen Deprivation Therapy (ADT) for a duration of 18-24 months. ADT will be initiated as neoadjuvant therapy 2-3 months prior to the commencement of radiotherapy.

Radiation: Simultaneous Integrated Boost Volumetric Modulated Arc Therapy (SIB-VMAT); Patients with histopathologically confirmed prostatic adenocarcinoma staged as high-risk / very high-risk localized disease will receive radiotherapy using Simultaneous Integrated Boost Volumetric Modulated Arc Therapy (SIB-VMAT) over a total duration of 4 weeks (20 consecutive working days). Target volumes: PTV-1 (PTV 44 Gy) Prostate + Pelvic Lymph Node PTV (PLNI): 44 Gy delivered in 20 fractions (2.2 Gy/fraction), including the internal iliac, external iliac, obturator, presacral nodal stations, whole prostate, and SV. PTV-2 (PTV 60 GY): 60 Gy delivered in 20 fractions (3 Gy/fraction), including the whole prostate and the base of the SV (proximal 1 cm). Systemic Therapy is allowed during the study when indicated. Patients will receive long-term Androgen Deprivation Therapy (ADT) for a duration of 18-24 months. ADT will be initiated as neoadjuvant therapy 2-3 months prior to the commencement of radiotherapy.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Acute and late GIT & GU toxicity	The incidence and severity of acute (during the radiation treatment and up to 3 months post-treatment) and late (after 3 months from finishing radiotherapy) gastrointestinal (GI) and genitourinary (GU) toxicities associated with the SIB-VMAT approach using CTCAE v5.0 and RTOG scale.	Day 1, Day 7, Day 14, Day 20 from radiation therapy start, then week 4, week 8, week 12 from radiation therapy end.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Early biochemical progression-free survival (bPFS)	Early biochemical control in terms of the serial measurement of serum PSA levels.	Day 1, Month 3, Month 6 and Month 12, from radiation therapy end.
Dosimetric plan evaluation	Dosimetric analysis of planning target volume coverage (PTV ): at least 95% of the volume must be covered with 95% of the prescribed radiation dose.; Dosimetric analysis of organs at risk (OAR) dose constraints, including rectum, urinary bladder, bowel, femoral heads, and penile bulb radiation doses, according to Quantec and Chipp trial dose constraints.	Baseline (Day 1 of radiation therapy start).

Collaborators and Investigators

• Sponsor: Ain Shams University

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2025
• Primary Completion (Estimated): September 1, 2026
• Study Completion (Estimated): November 1, 2026

Study Registration Dates

• First Submitted: June 28, 2026
• First Submitted That Met QC Criteria: July 3, 2026
• First Posted (Actual): July 9, 2026

Study Record Updates

• Last Update Posted (Actual): July 9, 2026
• Last Update Submitted That Met QC Criteria: July 3, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: High risk prostate cancer; SIB-VMAT Radiotherapy
• Other Study ID Numbers: Soh-Med-26-6-12PD

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No