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.