Stereotactic Radiotherapy for Prostate Cancer

(ADAPT-25 Trial)

Overseen By Cathy Tran

Age: 18+

Sex: Male

Trial Phase: Phase 2

Sponsor: British Columbia Cancer Agency

Must be taking: Androgen deprivation therapy

Disqualifiers: Stage cT3+, Gleason 8+, PSA 20+, others

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

Prior Safety Data This treatment has passed at least one previous human trial

Compensation: Varies

Number of Visits: 2

Duration: 2 weeks

100 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores a new method of delivering radiation treatment for prostate cancer that hasn't spread. The goal is to determine if two larger doses of radiation can control the disease as effectively as five smaller doses, while reducing side effects and improving convenience. Men diagnosed with low or intermediate risk levels of prostate cancer might be suitable candidates, particularly if the condition affects their daily life. The trial also tests a new AI-based computer tool to better target radiation, though this tool is tested separately and will not impact the treatment during the trial. As a Phase 2 trial, this research focuses on assessing the treatment's effectiveness in an initial, smaller group, offering participants a chance to contribute to advancements in prostate cancer care.

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications. However, if you are on Androgen Deprivation Therapy (ADT) for certain prostate cancer risks, you may continue it as part of the trial.

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

Research shows that stereotactic ablative body radiotherapy (SABR) for prostate cancer is generally easy for patients to handle. Studies have found that people receiving SABR often experience fewer side effects compared to traditional treatments. For instance, one study reported no severe side effects, indicating patients tolerated the treatment well.

Another study examined long-term results and found no deaths from prostate cancer among patients, demonstrating the treatment's safety and effectiveness. Additionally, tracking the prostate during treatment helps reduce side effects on nearby organs like the bladder. A rectal spacer, a small device placed between the prostate and rectum, also minimizes bowel side effects.

Overall, while the two-session SABR approach is newer and less studied than the five-session approach, early findings suggest it may be well-tolerated with the right precautions. This includes using technology to accurately track and target the prostate during treatment. ^{1 2 3 4 5}

Why are researchers excited about this trial's treatments?

Researchers are excited about Stereotactic Body Radiation Therapy (SBRT) for prostate cancer because it offers a more precise approach than traditional radiation therapy. Unlike standard treatments that often require multiple weeks of daily sessions, SBRT can deliver high doses of radiation directly to the prostate in just a few sessions over two weeks. The 5-fraction prostate SABR involves 40Gy delivered in five fractions, while the two-fraction SABR administers 27Gy in only two sessions. This precision and reduced treatment time could potentially lead to fewer side effects and more convenience for patients, making it a promising option for prostate cancer care.

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

Research has shown that prostate stereotactic ablative radiotherapy (SABR) can be as effective as traditional external beam radiotherapy for treating prostate cancer. Studies indicate that SABR provides excellent disease control and has fewer side effects than surgery, leading to a better quality of life. In this trial, participants will receive either SABR in five treatment sessions or SABR in two treatment sessions. One study found that SABR in five sessions works well for intermediate-risk prostate cancer and has good long-term results. Some smaller studies suggest that SABR in two sessions might also be very effective and easier for patients to handle, although direct comparisons to the five-session method are limited. Continuous tracking and a rectal spacer can help reduce side effects like bladder and bowel problems. ^{1 2 3 4 6}

Who Is on the Research Team?

Winkle Kwan

Principal Investigator

BC Cancer

Abraham Alexander

Principal Investigator

BC Cancer

Are You a Good Fit for This Trial?

Men with intermediate risk prostate cancer who haven't had their disease spread are eligible for this trial. It's not specified, but typically participants would need to be healthy enough for radiotherapy and meet certain medical criteria.

Inclusion Criteria

Able to provide informed consent

Life Expectancy > 5 years

PSA within 90 days prior to registration

Exclusion Criteria

My cancer has spread to the lymph nodes in my pelvis.

I have had radiation therapy to my pelvic area before.

PSA > 20ng/mL or greater

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

16 weeks

Treatment

Participants receive prostate stereotactic ablative radiotherapy (SABR) in either 2 or 5 fractions over 2 weeks

2 weeks

2-5 visits (in-person)

Follow-up

Participants are monitored for safety, quality of life, and disease control after treatment

5 years

AI Evaluation

Offline evaluation of AI-driven dose guidance/adaptive positioning application

3 years

What Are the Treatments Tested in This Trial?

Interventions

• Stereotactic Body Radiation Therapy (SBRT)

Trial Overview The ADAPT-2 study is testing whether treating prostate cancer with just 2 large doses of radiation (SABR) is as effective and safe as the standard 5-dose treatment. Both methods use tracking technology and a rectal spacer to minimize side effects, while also evaluating an AI application in simulation.

How Is the Trial Designed?

Group I: Two-Fraction Prostate SABR Experimental Treatment 1 Intervention

27Gy delivered to the prostate gland (CTV)in 2 fractions over 2 weeks

Group II: 5-fraction prostate SABR Active Control 1 Intervention

40Gy delivered to the prostate gland (CTV) in 5 fractions over 2 weeks.

Who Is Running the Clinical Trial?

British Columbia Cancer Agency

Lead Sponsor

Trials

181

Recruited

95,900+

Published Research Related to This Trial

Stereotactic body radiotherapy (SBRT) for localized prostate cancer showed a 5-year biochemical relapse-free survival (bRFS) rate of 93% across 1100 patients, indicating its effectiveness as a treatment option.

The study found no significant differences in outcomes based on the use of androgen deprivation therapy or total radiation dose, suggesting that SBRT is a robust treatment regardless of these factors.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Stereotactic body radiotherapy for localized prostate cancer: pooled analysis from a multi-institutional consortium of prospective phase II trials. King, CR., Freeman, D., Kaplan, I., et al.[2022]

In a study of 26 patients with low- or intermediate-risk prostate adenocarcinoma, stereotactic body radiation therapy (SBRT) showed excellent biochemical control with no observed failures after a median follow-up of 59.5 months.

The treatment resulted in manageable late toxicity, with only 11.5% of patients experiencing significant genitourinary or gastrointestinal side effects, and patient-reported quality of life remained stable compared to pre-treatment levels.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Prostate Stereotactic Body Radiation Therapy With a Focal Simultaneous Integrated Boost: 5-Year Toxicity and Biochemical Recurrence Results From a Prospective Trial. Maas, JA., Dobelbower, MC., Yang, ES., et al.[2023]

Stereotactic body radiotherapy (SBRT) for localized prostate cancer shows promising results, with studies indicating that ultra-hypofractionated schedules (like 42.7 Gy in 7 fractions) are non-inferior to standard treatments in terms of 5-year biochemical recurrence-free survival and have similar tolerability.

Current evidence suggests that two-fraction SBRT may be the shortest effective treatment schedule, but caution is advised against single-fraction SBRT due to concerns about inferior efficacy, highlighting the need for ongoing trials to determine optimal fractionation schedules.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The march toward single-fraction stereotactic body radiotherapy for localized prostate cancer-Quo Vadimus? Ong, WL., Loblaw, A.[2023]

Stereotactic body radiotherapy (SBRT) shows a high local control rate of 98.1% in treating oligorecurrent prostate cancer limited to lymph nodes, based on a systematic review of 363 patients across nine studies with a median follow-up of 19.23 months.

The treatment demonstrated a low incidence of toxicity, with only 5.6% of patients experiencing grade ≥2 adverse effects, and no cases of grade 4 toxicity, suggesting that SBRT is a safe option for this patient group.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Exploring All Avenues for Radiotherapy in Oligorecurrent Prostate Cancer Disease Limited to Lymph Nodes: A Systematic Review of the Role of Stereotactic Body Radiotherapy. Ponti, E., Lancia, A., Ost, P., et al.[2022]

In a study of 23 patients with high-risk prostate cancer, stereotactic body radiation therapy (SBRT) was found to be feasible and well tolerated, with low rates of severe gastrointestinal (GI) and genitourinary (GU) toxicities.

The treatment resulted in acute grade 1 GI toxicities in only 9.1% of patients and grade 3 GU toxicities in 4.5%, indicating that serious side effects were uncommon, but further long-term follow-up is needed to assess ongoing safety and efficacy.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Early Tolerance Outcomes of Stereotactic Hypofractionated Accelerated Radiation Therapy Concomitant with Pelvic Node Irradiation in High-risk Prostate Cancer. Pinitpatcharalert, A., Happersett, L., Kollmeier, M., et al.[2022]

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 phase I/II study involving 91 patients with localized prostate cancer, stereotactic body radiation therapy (SBRT) demonstrated a remarkable prostate-specific antigen (PSA) control rate of 99% over a median follow-up of 42 months.

While the maximum-tolerated dose (MTD) was not reached, the study noted a concerning 10.6% incidence of high-grade rectal toxicity at the highest dose level of 50 Gray, prompting the need for dose constraints to reduce this risk in future trials.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Stereotactic Body Radiation Therapy for Prostate Cancer: Review of Experience of a Multicenter Phase I/II Dose-Escalation Study. Kim, DW., Straka, C., Cho, LC., et al.[2022]

In a prospective phase II trial involving 110 patients aged 70 and older with localized prostate cancer, stereotactic body radiotherapy (SBRT) demonstrated a severe toxicity rate of less than 5%, confirming its safety for this patient population.

The SBRT regimen resulted in a biochemical progression-free survival (bPFS) rate of 90% over a median follow-up of 36 months, indicating its efficacy in treating localized prostate cancer without negatively impacting patients' quality of life.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Prospective validation of stringent dose constraints for prostatic stereotactic radiation monotherapy: results of a single-arm phase II toxicity-oriented trial. Nguyen, P., Harzée, L., Retif, P., et al.[2022]

Between 2006 and 2020, there was a significant increase in publications and citations related to stereotactic body radiotherapy (SBRT) for prostate cancer, indicating growing interest and research in this treatment method.

The United States led the research output in this field, with a focus on SBRT applications in oligometastatic disease, reirradiation, and salvage therapy, highlighting key areas for future investigation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Stereotactic Body Radiotherapy for Prostate Cancer: Where, When, and Who? A Bibliometric Analysis. Viani, GA., Gouveia, AG., Jacinto, AA., et al.[2023]

In a study of 174 hormone-naïve patients with localized prostate cancer treated with stereotactic body radiation therapy (SBRT), significant urinary symptoms were reported more frequently than bowel symptoms, with 51.6% of patients experiencing a clinically significant decline in urinary scores at 12 months.

The study indicates that while urinary and bowel symptoms initially increased after treatment, the proportion of patients reporting significant declines in these symptoms decreased from 12 to 36 months, suggesting potential late improvements in quality of life following SBRT.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Stereotactic Body Radiation Therapy for Prostate Cancer: What is the Appropriate Patient-Reported Outcome for Clinical Trial Design? Woo, JA., Chen, LN., Wang, H., et al.[2020]

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]

A study involving 803 patients analyzed the quality of life (QOL) impacts of SBRT, IMRT, and brachytherapy for localized prostate cancer, showing that all treatments resulted in good QOL two years post-treatment.

SBRT demonstrated similar outcomes to IMRT in urinary and sexual domains, but showed a significant improvement in bowel symptoms compared to brachytherapy, suggesting it may be a safer option with fewer side effects.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Patient-reported quality of life after stereotactic body radiotherapy (SBRT), intensity modulated radiotherapy (IMRT), and brachytherapy. Evans, JR., Zhao, S., Daignault, S., et al.[2022]

In a study of 713 men treated with stereotactic body radiation therapy (SBRT) for localized prostate cancer, only 3% to 4% experienced significant long-term declines in health-related quality of life (HRQOL), indicating that SBRT has minimal long-term negative effects on overall well-being.

Factors such as lower baseline bowel HRQOL and depression were found to predict declines in HRQOL, suggesting that comorbid conditions may play a larger role in patient outcomes than the treatment itself.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Predictors of multidomain decline in health-related quality of life after stereotactic body radiation therapy (SBRT) for prostate cancer. Dess, RT., Jackson, WC., Suy, S., et al.[2022]

Stereotactic body radiotherapy (SBRT) is shown to be safe and effective for treating node-positive prostate cancer, with a median follow-up of 30 months revealing no severe gastrointestinal toxicities and manageable genitourinary side effects.

In a study of 60 patients, SBRT resulted in a 3-year overall survival rate of 89% and a biochemical failure-free survival rate of 77%, indicating promising long-term outcomes even in patients with advanced disease.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Safety and Efficacy of Ultra-hypofractionation in Node-positive Prostate Cancer. Telkhade, T., Murthy, V., Kanala, TS., et al.[2021]

Citations

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

Stereotactic ablative body radiotherapy in patients with ... Efficacy for SABR appears to be similar to brachytherapy including positive biopsy rates 2–3 years post treatment, biochemical failure (BF) rates out to 10-year ...

2. asco.org asco.org/abstracts-presentations/ABSTRACT482100

Five-year outcomes of SABR in intermediate- and high-risk ... Most existing studies have primarily focused on low- and intermediate-risk PCa patients, who typically have favorable prognoses regardless of treatment.

3. 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 ...

4. 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.

5. cancer.gov cancer.gov/news-events/cancer-currents-blog/2024/prostate-cancer-sbrt-effective-safe

SBRT Proves Effective for Some Prostate Cancers - NCI Trial participants who were randomly assigned to receive SBRT had a higher risk of developing some urinary problems over the first 2 years after ...

6. 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