The Use of PSMA PET/CT Improves Overall Survival in Men with Biochemically Recurrent Prostate Cancer Treated with Salvage Radiotherapy: Real-World Data from an Entire Country

International guidelines recommend salvage radiotherapy (sRT) as a curative treatment for men with biochemically recurrent prostate cancer after radical prostatectomy. Prostate-specific membrane antigen (PSMA) PET/CT has demonstrated high sensitivity for localizing recurrent disease at low prostate-specific antigen levels, enabling improved treatment decision-making. However, few studies have investigated the impact of pre-sRT PSMA PET/CT on patient-relevant outcomes, that is, recurrence-free and overall survival. Moreover, no comparison exists of overall survival between patients who underwent PSMA PET/CT and those who did not, before sRT. Methods: This study used real-world data (obtained from routine clinical practice) of all patients treated with sRT in Denmark from 2015 through 2023. Patients were categorized according to whether they underwent pretreatment PSMA PET/CT. Our main objective was to compare overall survival up to 5 y after completion of sRT. Biochemical recurrence-free survival (BRFS) was included as a secondary outcome. Only patients with a prostate-specific antigen value of 0.2-1.0 ng/mL were included. Results: In total, 844 patients were treated with sRT during the study period, of whom 308 (36.5%) underwent pretreatment PSMA PET/CT. The analysis revealed greater overall survival for patients who underwent PSMA PET/CT before sRT than for patients who did not. The 1-, 2-, and 5-y survival rates for PSMA PET/CT patients were 100% (95% CI, 100%-100%), 99.5% (95% CI, 98.6%-100%), and 98.1% (95% CI, 96%-100%), respectively, versus 99% (95% CI, 98.2%-99.9%), 97.8% (95% CI, 96.5%-99.1%), and 93.8% (95% CI, 91.5%-96.2%), respectively, for non-PSMA PET/CT patients (crude hazard ratio, 3.31 [95% CI, 1.01-10.88]; P = 0.0486). Comparatively, the 3-y BRFS rate was consistent with overall survival: 74.9% (95% CI, 68.5%-81.3%) for PSMA PET/CT patients and 69.4% (95% CI, 65.2%-73.7%) for non-PSMA PET/CT patients, with a hazard ratio of 1.53 (95% CI, 1.07-2.19; P = 0.0187). Conclusion: PSMA PET/CT use before sRT was associated with improved overall survival and BRFS.