SABR Treatments for Prostate Cancer

(iSMART Trial)

Overseen By Danny Vesprini, MD

Age: 18+

Sex: Male

Trial Phase: Academic

Sponsor: Sunnybrook Health Sciences Centre

Must not be taking: Androgens, Anticoagulants, Immunosuppressives

Disqualifiers: Prior pelvic radiotherapy, Bleeding diathesis, Large prostate, Inflammatory bowel disease, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Approved in 4 Jurisdictions This treatment is already approved in other countries

Compensation: Varies

Number of Visits: 3

Duration: 2-5 weeks

144 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores a new, shorter radiation treatment for men with localized prostate cancer. The study compares two radiation schedules: one with two weekly sessions and another with five sessions every other day. Researchers aim to determine if the shorter schedule is as effective as the traditional one. Men with prostate cancer who have not undergone hormone therapy or previous radiotherapy might be eligible. Those with a confirmed diagnosis of low or favorable intermediate risk prostate cancer may find this trial suitable. As an unphased trial, this study provides a unique opportunity to contribute to innovative research that could enhance future treatment options.

Do I need to stop my current medications for the trial?

The trial requires you to stop taking anticoagulation and immunosuppressive medications. If you are on these, you may need to discontinue them to participate.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Past studies have shown that Stereotactic Ablative Body Radiation (SABR) is a safe treatment for prostate cancer. Research indicates that patients generally tolerate SABR well, with long-term studies showing positive results similar to other common treatments like brachytherapy. For instance, one study found no major differences in long-term cancer outcomes when comparing different SABR schedules, highlighting its flexibility and safety.

Moreover, SABR is recognized as a standard treatment for various risk levels of prostate cancer, further supporting its safety. Some studies suggest that shorter treatment times might lead to fewer side effects affecting quality of life. Overall, SABR has a strong record of safety and effectiveness in treating prostate cancer. ^{1 2 3 4 5}

Why are researchers excited about this trial's treatments?

Researchers are excited about these treatments for prostate cancer because Stereotactic Ablative Body Radiation (SABR) offers a unique approach. Unlike traditional radiation therapy options, which often involve lower doses over a longer period, SABR delivers high doses of radiation in fewer sessions. Arm 1 uses just two weekly fractions of 13.5 Gy, while Arm 2 involves five fractions of 8 Gy every other day. This could mean fewer trips to the clinic and a more convenient treatment process for patients, potentially leading to quicker recovery times and less disruption to daily life.

What evidence suggests that this trial's treatments could be effective for prostate cancer?

Research has shown that Stereotactic Ablative Body Radiation (SABR) effectively treats prostate cancer. This trial will compare two different SABR schedules: one group will receive two weekly fractions of 13.5 Gy, while another group will receive five every-other-day fractions of 8 Gy. Studies have found that SABR controls cancer well and is convenient due to fewer treatment sessions. One study found no major differences in long-term cancer outcomes between different SABR schedules, offering flexibility in treatment timing. Another study showed that SABR is as effective as other radiation treatments for patients with lower-risk prostate cancer. Overall, SABR is known for its effectiveness and practicality in managing prostate cancer. ^{1 2 6 7 8}

Who Is on the Research Team?

Danny Vesprini, MD

Principal Investigator

Sunnybrook Health Sciences Centre

Are You a Good Fit for This Trial?

Men with confirmed prostate adenocarcinoma, classified as low risk (T1-T2b, grade group 1, PSA <10 ng/ml) or favorable intermediate risk. Intermediate risk is defined by only one factor: cT2c, grade group 2, PSA between 10-20 ng/ml; or Grade group 3 with PSA <20 and <cT2c where pattern 4/5 is less than 10%.

Inclusion Criteria

My prostate cancer is considered favorable risk with limited intermediate risk factors.

My prostate cancer is early stage, low grade, and my PSA is under 10.

My prostate cancer diagnosis was confirmed through a biopsy.

Exclusion Criteria

I am receiving or will receive hormone therapy for my cancer.

My prostate is larger than 90cm3 according to scans.

I am not taking any immunosuppressive medications.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants receive either two weekly fractions of 13.5 Gy or five every other day fractions of 8 Gy of stereotactic ablative body radiotherapy (SABR)

2-5 weeks

2-5 visits (in-person)

Follow-up

Participants are monitored for safety, effectiveness, and quality of life changes after treatment

5 years

Visits at week 1, 4, 13; month 6; and every 6 months for 5 years

What Are the Treatments Tested in This Trial?

Interventions

• Stereotactic Ablative Body Radiation

Trial Overview

The trial compares two different schedules of delivering radiation for prostate cancer treatment. One uses the standard five sessions of SABR while the experimental approach condenses this into just two treatments a week apart to see if it's equally effective.

How Is the Trial Designed?

Group I: Arm 1 Experimental Treatment 1 Intervention

Two weekly fractions of 13.5 Gy

Group II: Arm 2 Active Control 1 Intervention

Five every other day fractions of 8 Gy

Stereotactic Ablative Body Radiation is already approved in United States, European Union, Canada, Japan for the following indications:

Approved in United States as Stereotactic Body Radiation Therapy (SBRT) for:

• Prostate cancer
• Lung cancer
• Liver cancer
• Spine cancer
• Pancreatic cancer
• Kidney cancer

Approved in European Union as Stereotactic Ablative Radiotherapy (SABR) for:

• Prostate cancer
• Lung cancer
• Liver cancer
• Spine cancer
• Pancreatic cancer
• Kidney cancer

Approved in Canada as Stereotactic Body Radiation Therapy (SBRT) for:

• Prostate cancer
• Lung cancer
• Liver cancer
• Spine cancer
• Pancreatic cancer
• Kidney cancer

Approved in Japan as Stereotactic Ablative Radiotherapy (SABR) for:

• Prostate cancer
• Lung cancer
• Liver cancer
• Spine cancer
• Pancreatic cancer
• Kidney cancer

Who Is Running the Clinical Trial?

Sunnybrook Health Sciences Centre

Lead Sponsor

Trials

693

Recruited

1,569,000+

Prostate Cure Foundation

Collaborator

Trials

2

Recruited

220+

Published Research Related to This Trial

In a study of 66 prostate cancer patients treated with ultra-hypofractionated stereotactic body radiation therapy (SBRT), the treatment demonstrated excellent biochemical control, with a 2-year freedom from biochemical failure (FFBF) rate of 88.4%.

The treatment was associated with low toxicity, as no patients experienced severe (grade ≥3) genitourinary toxicity, and only 13.6% experienced grade 2 toxicities, indicating that SBRT is a safe option for postoperative prostate cancer management.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Treatment outcomes of postoperative ultra-hypofractionated stereotactic body radiotherapy in prostate cancer. Ozyigit, G., Onal, C., Beduk Esen, CS., et al.[2023]

In a study involving 51 prostate cancer patients treated with stereotactic body radiotherapy (SBRT), the treatment showed promising outcomes with manageable toxicity levels, as no patients experienced severe (grade 3+) side effects during the initial follow-up period.

The median follow-up of 14.5 months revealed a low prostate-specific antigen level of 1.3 ng/ml at 13-18 months post-treatment, indicating effective disease control in this cohort.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Prostate stereotactic body radiotherapy—first UK experience. Tree, AC., Ostler, P., Hoskin, P., et al.[2022]

In a study of 205 prostate cancer patients treated with stereotactic body radiation therapy (SBRT), 99% completed the treatment without severe acute side effects, indicating that this method is safe and well-tolerated.

The most common acute side effects were mild to moderate, with 50.7% experiencing grade II genitourinary issues and 31.7% experiencing grade I gastrointestinal issues, but no patients had severe (grade ≥ 4) toxicity.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Acute side effects after definitive stereotactic body radiation therapy (SBRT) for patients with clinically localized or locally advanced prostate cancer: a single institution prospective study. Jorgo, K., Polgar, C., Stelczer, G., et al.[2022]

A single session of stereotactic ablative body radiotherapy (SABR) for oligometastatic prostate cancer was found to be feasible and safe, with only one significant adverse event (a vertebral fracture) reported among 33 patients over a 2-year follow-up period.

The treatment resulted in high local progression-free survival rates of 97% at 1 year and 93% at 2 years, with nearly half of the patients (48%) avoiding the need for androgen deprivation therapy at the 2-year mark, indicating effective disease control and maintained quality of life.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Stereotactic Abative Body Radiotherapy (SABR) for Oligometastatic Prostate Cancer: A Prospective Clinical Trial. Siva, S., Bressel, M., Murphy, DG., et al.[2022]

Stereotactic ablative radiotherapy (SABR) has been shown to be feasible and well tolerated for low- and intermediate-risk prostate cancer patients, with promising results from large randomized studies comparing it to conventional treatments.

While SABR shows potential benefits and cost-effectiveness, there is currently insufficient data to recommend its use for high-risk prostate cancer patients outside of clinical trials.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Stereotactic Ablative Body Radiotherapy for Intermediate- or High-Risk Prostate Cancer. Loblaw, A.[2021]

Stereotactic body radiation therapy (SBRT) for localized prostate cancer showed a high two-year biochemical relapse-free survival rate of 99%, indicating its efficacy in controlling the disease.

The treatment was well tolerated, with low rates of gastrointestinal (1%) and genitourinary (31%) toxicities, and most patients who were sexually potent before treatment maintained their potency two years later.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Stereotactic body radiation therapy (SBRT) for clinically localized prostate cancer: the Georgetown University experience. Chen, LN., Suy, S., Uhm, S., et al.[2022]

Stereotactic ablative body radiotherapy (SABR) is an advanced treatment that delivers high doses of radiation in fewer sessions while protecting surrounding healthy tissues, making it effective for small tumors in various locations, including the prostate.

SABR is becoming a standard treatment for low and intermediate-risk prostate cancer, supported by research from Sunnybrook and the US prostate SABR consortium, highlighting its efficacy in improving patient outcomes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Evolution of hypofractionated accelerated radiotherapy for prostate cancer - the sunnybrook experience. Musunuru, HB., Cheung, P., Loblaw, A.[2022]

In a study of 558 men with localized prostate cancer, there was no significant difference in overall survival between those treated with stereotactic body radiotherapy (SBRT) plus androgen deprivation therapy (ADT) and those receiving conventional external beam radiotherapy (EBRT) plus ADT, after a median follow-up of 74 months.

The findings support recent NCCN guidelines that classify SBRT as a non-preferred option for higher-risk prostate cancer, indicating that both treatment modalities have similar efficacy in terms of survival outcomes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Stereotactic body radiotherapy versus conventional/moderate fractionated radiation therapy with androgen deprivation therapy for unfavorable risk prostate cancer. Patel, SA., Switchenko, JM., Fischer-Valuck, B., et al.[2021]

A systematic review of studies on stereotactic body radiation therapy (SBRT) for prostate cancer found that most patients experienced mild to moderate side effects, with severe toxicity occurring in less than 3% of cases, indicating that SBRT is generally well tolerated.

The review identified important dosimetric factors that influence toxicity, such as recommended dose constraints for the bladder, urethra, and rectum, which can help optimize treatment safety and effectiveness.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Prostate Stereotactic Body Radiation Therapy: An Overview of Toxicity and Dose Response. Wang, K., Mavroidis, P., Royce, TJ., et al.[2022]

Citations

1.

pmc.ncbi.nlm.nih.gov

pmc.ncbi.nlm.nih.gov/articles/PMC6043737/

Stereotactic ablative body radiotherapy in patients with ...

There are moderately strong data supporting the use of radiotherapy (RT) for node positive prostate cancer (5) and the role of radiotherapy for metastatic ...

2.

sciencedirect.com

sciencedirect.com/science/article/pii/S2588931125000860

Long-term Oncological Outcomes in the Phase 2 PATRIOT ...

This study suggests no significant differences in long-term cancer outcomes between EOD and QW schedules for five-fraction prostate SABR.

3.

thelancet.com

thelancet.com/journals/lanonc/article/PIIS1470-2045(25)00205-0/abstract

early toxicity results from a randomised, open-label, phase ...

Stereotactic body radiotherapy (SBRT) is also effective, and has been shown to be non-inferior to MHRT in a lower-risk group of patients who did ...

4.

thegreenjournal.com

thegreenjournal.com/issue/S0167-8140(25)X0003-7?pageStart=26

May 2025

Prostate cancer focal boost versus no boost in 20 fraction external beam radiotherapy: a prospective cohort on dosimetry, toxicity and quality of life

5.

frontiersin.org

frontiersin.org/journals/oncology/articles/10.3389/fonc.2022.779182/full

Dose-Intensified Stereotactic Ablative Radiation for ...

Purpose: Stereotactic ablative radiation (SAbR) has been increasingly used in prostate cancer (PCa) given its convenience and cost efficacy.

6.

clinicaltrials.gov

clinicaltrials.gov/study/NCT06325046?term=John

Adaptive Radiation Therapy (ART) Stereotactic Ablative ...

Shorter duration near margin-less ART may be just as effective at treating patients with localized prostate cancer but have less quality of life side effects ...

7.

uclahealth.org

uclahealth.org/departments/radonc/research-technologies/innovation-technology/external-beam-radiation-therapy-ebrt/stereotactic-body-radiation-therapy-sbrt/sbrt-prostate-cancer

SBRT for Prostate Cancer - Radiation Oncology

SBRT is considered a standard of care option for any patient with low through very-high risk prostate cancer who is considering radiation therapy.

8.

jamanetwork.com

jamanetwork.com/journals/jamanetworkopen/fullarticle/2723641

Long-term Outcomes of Stereotactic Body Radiotherapy for ...

This cohort study of pooled individual patient data assesses long-term outcomes after stereotactic body radiotherapy for low-risk and ...