Acute Toxicity and Early Prostate Specific Antigen Response After Two-Fraction Stereotactic Radiation Therapy for Localized Prostate Cancer Using Peri-Rectal Spacing-Initial Report of the SABR-Dual Trial

Two-fraction Versus Five-fraction Stereotactic Body Radiotherapy for Intermediate-risk Prostate Cancer: The TOFFEE Meta-analysis of Individual Patient Data from Four Prospective Trials

BACKGROUND AND OBJECTIVE

Recent randomized controlled trials have demonstrated the efficacy of five-fraction stereotactic body radiotherapy (5F-SBRT) for prostate cancer (PC), but there is no comparative evidence for fewer fractions. We compare outcomes of prostate two-fraction SBRT (2F-SBRT) and 5F-SBRT using prospective data for patients with intermediate-risk (IR) PC.

METHODS

This meta-analysis of individual patient data evaluated IR-PC from four prospective trials of prostate SBRT (two trials each of 2F- and 5F-SBRT). The primary endpoint was the cumulative incidence of biochemical failure (BCF). Secondary endpoints included the cumulative incidence of distant metastases (DM) and patient-reported quality of life (QoL).

KEY FINDINGS AND LIMITATIONS

Of the 199 patients meeting the eligibility criteria, 143 (72%) were in the 5F-SBRT group and 56 (28%) were in the 2F-SBRT group. Median follow-up was 9.4 years. There was no significant difference in BCF with a 5-year cumulative incidence of 3.6% (95% CI 0-8.6%) in the 2F-SBRT group and 6.0% (95% CI 1.8-10.2%) in the 5F-SBRT group (p = 0.73). There was no significant difference in DM incidence. We found no differences in acute and late urinary or bowel QoL. Limitations include the non-randomized comparison.

CONCLUSIONS AND CLINICAL IMPLICATIONS

We report the first prospective comparison of prostate 2F-SBRT and 5F-SBRT. We found no significant difference in efficacy, or in urinary or bowel QoL. This meta-analysis further encourages the potential of 2F-SBRT to be a standard-of-care option for IR PC.

Implantable Rectal Spacers in Prostate Cancer Radiation Therapy: A Systematic Review

PURPOSE

This systematic review provides an overview of the available literature regarding the efficacy and safety of implantable rectal spacers (IRSs) in reducing rectal dose and gastrointestinal toxicity during prostate cancer radiation therapy.

METHODS AND MATERIALS

A comprehensive literature search was conducted in December 2024. Results included prospective research in humans and were limited to the English language. The 30 included studies, all published between 2007 and 2024, were randomized controlled trials or clinical trials that focused on adverse events, rectal dose reduction, gastrointestinal toxicity, or bowel quality of life. Next, IRS implantation technique, safety, and spacing distance were assessed.

RESULTS

Randomized controlled trial data were available for hydrogel, hyaluronic acid, and rectal balloon implant spacers, whereas only one pilot study is available for human collagen. Prospective clinical research on IRS in brachytherapy is limited. One centimeter of spacing between the rectum and prostate sufficed to spare the rectum, the primary dose-limiting organ. Findings indicate a favorable safety profile, with an overall complication rate of 0,96% when using hydrogel spacers. There was no grade 4 to 5 gastrointestinal toxicity reported in clinical trials. The use of an IRS was associated with improved long-term bowel quality of life.

CONCLUSIONS

The integration of IRS into clinical practice offers the potential to enhance the therapeutic landscape for patients with prostate cancer. However, its use should be guided by careful consideration of individual patient needs to determine those who benefit most from the IRS because not all patients may benefit equally.

Does biodegradable peri-rectal spacer mitigate treatment toxicities in radiation therapy for localised prostate cancer-a systematic review and meta-analysis

INTRODUCTION

There is an increasing use of biodegradable peri-rectal spacer prior to radiation therapy for prostate cancer to reduce treatment-associated rectal toxicity. While data from individual trials and cohorts is maturing, there is a lack of an updated quantitative analysis that includes outcomes following peri-rectal spacer. We aim to delineate the clinical impact of peri-rectal spacer in localised prostate cancer patients treated with radiotherapy.

METHODS

In March 2024, a systematic search was performed on MEDLINE, Embase, and Cochrane Central Register of controlled trials for publications since the year 2010. Prospective and retrospective studies reporting comparative outcomes of patients with and without peri-rectal spacer prior to radiotherapy were considered. Outcomes are reported in binary fashion. Random effect meta-analysis with the use of weighted mean difference was adopted. Early (≤3 months) and late rectal toxicity stratified according to the Common Terminology Criteria for Adverse Events (CTCAE) criteria, early and late genitourinary toxicity, quality of life in bowel, sexual and urinary domains (in terms of minimal clinically important difference) were assessed.

RESULTS

The systematic review included 17 studies. There are 3 RCTs, 3 prospective cohorts, and 11 retrospective cohorts. Three thousand two hundred patients were included, with 1471 patients who received peri-rectal spacer and 1729 without. The use of spacer is associated with lower likelihood of late (1.62% vs. 9.35%, RR = 0.25, 95% CI = 0.15-0.42, P < 0.001) and early grade 2 or above late rectal toxicity (3.07% vs. 6.05%, RR = 0.53, 95% CI = 0.33-0.86, P < 0.001). No difference is observed in significant grade 3 or above GI (acute or late) events. There is no statistical difference in bowel-related bowel QoL (risk difference = -0.16, 95% CI = -0.38-0.06, P = 0.15). The perirectal spacer is not associated with negative impact to urinary or sexual domains of QoL either.

CONCLUSION

In localised prostate cancer patients treated with radiation therapy, the use of peri-rectal spacer is associated with reduced rectal toxicities.