A comprehensive Danish study has provided the first real-world evidence that prostate-specific membrane antigen (PSMA) PET/CT imaging before salvage radiotherapy significantly improves survival outcomes in men with biochemically recurrent prostate cancer. The nationwide analysis, published in The Journal of Nuclear Medicine, demonstrates superior overall survival and biochemical recurrence-free survival rates for patients who underwent PSMA PET/CT compared to those who did not.
Study Design and Patient Population
Researchers analyzed data from Denmark's nationwide health registry covering all patients who received salvage radiotherapy between 2015 and 2023. The study included 844 patients with biochemically recurrent prostate cancer and prostate-specific antigen levels between 0.2 to 1.0 ng/mL. Of these patients, 308 (36.5%) underwent PSMA PET/CT before treatment, while 536 (63.5%) did not receive the imaging.
The study design took advantage of Denmark's gradual adoption of PSMA PET/CT technology, which was introduced in 2015 but not implemented simultaneously across all regions. This created a natural comparison group for evaluating the clinical impact of the imaging modality.
Survival Outcomes Show Clear Benefit
The analysis revealed significantly improved overall survival rates for patients who underwent PSMA PET/CT before salvage radiotherapy. At one year, the overall survival rate was 100% for PSMA PET/CT patients compared to 99% for non-PSMA PET/CT patients. This survival advantage persisted over time, with two-year rates of 99.5% versus 97.8% and five-year rates of 98.1% versus 93.8%, respectively.
The crude hazard ratio for overall survival favored the PSMA PET/CT group (HR 3.31; 95% CI, 1.01 to 10.88; P = 0.0486), indicating a statistically significant survival benefit.
Biochemical Recurrence-Free Survival Also Improved
Biochemical recurrence-free survival rates similarly favored patients who received PSMA PET/CT imaging. The one-year biochemical recurrence-free survival rate was 91.3% for PSMA PET/CT patients compared to 74.9% for those who did not receive the imaging. At three years, these rates were 74.9% and 69.4%, respectively (adjusted HR 1.53; 95% CI, 1.07 to 2.19; P = 0.0187).
According to the researchers, these biochemical recurrence-free survival rates corresponded to a relative risk reduction of 42% after one year of follow-up and 18% after three years.
Clinical Implications for Treatment Selection
"Our findings show that PSMA PET/CT scans can help clinicians select the patients most likely to experience success with salvage radiotherapy," said Anna W. Mogensen, MSc, a PhD student at the Department of Nuclear Medicine at Aalborg University Hospital and lead author of the study. "This means fewer patients may receive unnecessary treatment, while more will be provided with the appropriate care."
The study addresses a critical gap in understanding the clinical value of PSMA PET/CT. While the imaging modality has been widely accepted as more accurate than other methods for detecting recurrent prostate cancer, its impact on patient outcomes had not been definitively established.
Context of Salvage Radiotherapy
Biochemical recurrence after radical prostatectomy occurs in up to 40% of prostate cancer patients, making salvage radiotherapy a crucial treatment option. The success of salvage radiotherapy depends heavily on accurate imaging to precisely locate recurrences for targeted treatment. Previously, physicians relied on bone scintigraphy, CT, or MRI, but PSMA PET/CT has emerged as the preferred modality due to its superior diagnostic capability.
Study Limitations and Future Directions
The researchers acknowledged several limitations of their observational study design, including the inability to control for certain confounding factors due to the limited number of events in the PSMA PET/CT group. The median follow-up was also shorter in the PSMA PET/CT arm at 30.0 months compared to 68.4 months in the non-PSMA PET/CT arm.
"Ideally, these findings should be confirmed in a randomized trial," the authors noted in their publication.
Despite these limitations, the study's findings support the broader use of nuclear medicine techniques to guide therapy and suggest that integrating advanced imaging early in treatment decisions could become a new standard in cancer care. The research provides compelling real-world evidence for the clinical value of PSMA PET/CT in improving outcomes for men with recurrent prostate cancer undergoing salvage radiotherapy.
