Whole Versus Partial Gland Boost During Prostate SBRT

A Phase 2/3 Randomized Trial of Whole Versus Partial Gland Boost During Prostate Stereotactic Body Radiotherapy (SBRT)

This phase 2/3 randomized trial evaluates whether dose escalation to the dominant intra-prostatic lesion (DIL) compared to whole gland dose escalation during prostate stereotactic body radiotherapy (SBRT) results in differences in genitourinary (GU) and gastrointestinal (GI) toxicities.

Study Overview

• Status: Not yet recruiting
• Conditions: Prostate Cancer; Prostate Adenocarcinoma
• Intervention / Treatment: Radiation: Prostate stereotactic body radiotherapy with whole gland boost; Radiation: Prostate stereotactic body radiotherapy with DIL boost

Detailed Description

This is a phase 2/3 randomized clinical trial evaluating two dose escalation strategies during prostate stereotactic body radiotherapy (SBRT). A total of 186 patients with prostate adenocarcinoma will be enrolled and randomized in a 1:1 ratio to one of two treatment arms.

In both arms, patients will receive 3625 cGy delivered to the planning target volume (PTV) over 5 fractions. In Arm A, patients will receive a boost to the prostate gland. In Arm B, patients will receive a boost to the dominant intra-prostatic lesion (DIL) identified on pre-treatment magnetic resonance imaging (MRI).

The primary objective is to evaluate chronic genitourinary (GU) and gastrointestinal (GI) toxicities grade 2 or higher from 6 months to 2 years post-treatment using the Common Terminology Criteria for Adverse Events (CTCAE). Secondary objectives include evaluation of acute and chronic GU and GI toxicities using CTCAE, Radiation Therapy Oncology Group (RTOG), and Expanded Prostate Cancer Index Composite (EPIC) domains, as well as biochemical progression-free survival at 5 years.

Participants will be followed for up to 5 years after completion of treatment.

• Study Type: Interventional
• Enrollment (Estimated): 186
• Phase: Phase 2; Phase 3

Contacts and Locations

• Study Contact: Name: Krishna Gottipati, MS; Phone Number: 4025593518; Email: krgottipati@unmc.edu
• Study Contact Backup: Name: IIT Office Gottipati; Phone Number: 4025590963; Email: IITOFFICE@unmc.edu

Study Locations

• United States
  • Nebraska
    • Omaha, Nebraska, United States, 68198
      • Fred & Pamela Buffet Cancer Center
      • Contact: Michael Baine, MD, PhD; Phone Number: (402) 552-2703; Email: mbaine@unmc.edu

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

1. Adults ≥19 years of age
2. Patients with a diagnosis of prostate adenocarcinoma for which stereotactic body radiotherapy (SBRT) to the prostate ± proximal seminal vesicles is being offered
3. Prostate gland volume <100 cc prior to initiation of androgen deprivation therapy (ADT), as reported at time of biopsy or by imaging (e.g., ultrasound, MRI, or CT)
4. PI-RADS 4 or 5 lesion seen on pre-treatment MRI
5. IPSS/AUA symptom score less than 16

Exclusion Criteria:

1. Prior treatment for prostate cancer
2. Prior solid cancer diagnosis within the last 5 years
3. Any history of anal or rectal cancer
4. Any history of invasive carcinoma of the bladder
5. History of prior circumferential resection of the rectum (such as LAR or APR)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Arm A: boost to prostate alone; Participants assigned to Arm A will receive external beam radiation therapy consisting of 3625 cGy to the planning target volume (PTV), plus a boost of 4000 cGy to the clinical target volume (CTV), consisting of the prostate alone without a margin. Treatment will be delivered over 5 fractions with at least 36 hours between fractions via simultaneous integrated boost (SIB).	Radiation: Prostate stereotactic body radiotherapy with whole gland boost; External beam radiation therapy delivered via linear accelerator-based SBRT using simultaneous integrated boost
Experimental: Arm B: boost to dominant intra-prostatic lesion (DIL); Participants assigned to Arm B will receive external beam radiation therapy consisting of 3625 cGy to the planning target volume (PTV), plus a boost of 4500 cGy to the dominant intra-prostatic lesion (DIL). Treatment will be delivered over 5 fractions with at least 36 hours between fractions via simultaneous integrated boost (SIB).	Radiation: Prostate stereotactic body radiotherapy with DIL boost; External beam radiation therapy delivered via linear accelerator-based SBRT using simultaneous integrated boost to the dominant intra-prostatic lesion.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Grade 2 or Higher Chronic Genitourinary Toxicity	Cumulative incidence of grade 2 or higher chronic genitourinary (GU) toxicities assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0	From 6 months post-treatment to 2 years post-treatment
Grade 2 or Higher Chronic Gastrointestinal Toxicity	Cumulative incidence of grade 2 or higher chronic gastrointestinal (GI) toxicities assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0	From 6 months post-treatment to 2 years post-treatment

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Biochemical Progression-Free Survival	Time from initiation of study treatment to biochemical disease progression or death from any cause.	From initiation of study treatment to 5 years post-treatment
Acute Gastrointestinal Toxicity	Cumulative incidence of acute gastrointestinal (GI) toxicities assessed using CTCAE, Radiation Therapy Oncology Group (RTOG), and Expanded Prostate Cancer Index Composite (EPIC) domains.	From end of treatment to 6 months post-treatment
Acute Genitourinary Toxicity	Cumulative incidence of acute genitourinary (GU) toxicities assessed using CTCAE, RTOG, and EPIC domains.	From end of treatment to 6 months post-treatment
Chronic Gastrointestinal Toxicity	Incidence of chronic gastrointestinal (GI) toxicities assessed using CTCAE, RTOG, and EPIC domains.	From 6 months post-treatment to 5 years post-treatment
Chronic Genitourinary Toxicity	Incidence of chronic genitourinary (GU) toxicities assessed using CTCAE, RTOG, and EPIC domains.	From 6 months post-treatment to 5 years post-treatment

Collaborators and Investigators

• Sponsor: University of Nebraska
• Investigators: Principal Investigator: Michael Baine, MD, PhD, University of Nebraska medicine

Study record dates

Study Major Dates

• Study Start (Estimated): July 25, 2026
• Primary Completion (Estimated): August 25, 2032
• Study Completion (Estimated): August 25, 2035

Study Registration Dates

• First Submitted: April 30, 2026
• First Submitted That Met QC Criteria: April 30, 2026
• First Posted (Actual): May 8, 2026

Study Record Updates

• Last Update Posted (Actual): May 13, 2026
• Last Update Submitted That Met QC Criteria: May 8, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Radiation Therapy; CTCAE; Dose Escalation; Stereotactic Body Radiotherapy; DIL; EPIC; Dominant Intraprostatic Lesion; Prostate SBRT; Genitourinary Toxicity; Gastrointestinal Toxicity; RTOG
• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Genital Neoplasms, Male; Urogenital Neoplasms; Neoplasms by Site; Neoplasms; Genital Diseases, Male; Prostatic Diseases; Male Urogenital Diseases; Prostatic Neoplasms
• Other Study ID Numbers: Gland Boost

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No