Can single metastasis-directed radiotherapy (MDRT) have an impact for oligometastatic prostate cancer (PCa)?
In a retrospective study, recently published in European Urology Oncology, researchers evaluated metastasis-directed radiotherapy (MDRT) in 80 patients (median age of 65) with hormone-sensitive, metachronous oligometastatic PCa with a total of 105 PCa lesions. Oligometastatic PCa was defined as the involvement of one to four lymph nodes and/or bone metastases on prostate-specific membrane antigen (PSMA) positron emission tomography (PET), according to the study.
The authors found that local disease remission with prostate cancer occurred in 87 percent of patients after MDRT, and 85 percent of patients restaged with PSMA PET/CT had no PSMA-expressing lesions at sites of treatment.
However, at a median 32-month follow-up after MDRT, the researchers pointed out that 80 percent had biochemical progression of PCa. Follow-up PSMA PET/CT also revealed new metastatic disease for 72 percent of patients who had local remission of PCa.
“Despite excellent local remission rates in our cohort, most patients experienced biochemical and ultimately distant progression,” wrote lead study author Katelijne C.C. de Bie, M.D., who is affiliated with the Amsterdam University Medical Center and Vrije University in Amsterdam, the Netherlands, and colleagues.
The study authors noted that 51 percent of the cohort had salvage therapy for suspected local PC recurrence prior to the diagnosis of oligometastatic PCa.
Three Key Takeaways
1. High local control but frequent systemic progression. MDRT achieved local remission in 87 percent of patients, but 80 percent experienced biochemical progression and 72 percent developed new metastases within a median of 32 months, indicating limited long-term systemic control.
2. Prior salvage therapy improves outcomes. Patients who had prior salvage therapy demonstrated better biochemical progression-free survival (66 percent vs. 41 percent) and longer median bPFS (13 vs. 8 months), suggesting a potential benefit from combining MDRT with earlier interventions.
3. MDRT Is low burden and may be suitable for select patients. Despite modest long-term outcomes, MDRT remains a low-toxicity and cost-effective option, particularly for patients with slow disease progression and limited metastases.
Patients with prior salvage therapy had a 25 percent higher biochemical progression-free survival (bPFS) rate (66 percent vs. 41 percent) as well as a five-month longer median bPFS (13 months vs. eight months) in comparison to those without prior salvage therapy, according to the researchers.
“Although the oncological outcomes were disappointing, MDRT remains a valuable treatment with low toxicity, minimal patient burden, and low cost. We believe that MDRT as a stand-alone approach should not be dismissed in current clinical practice as it may be appropriate for patients with slowly progressing oligometastatic disease,” maintained Bie and colleagues.
(Editor’s note: For related content, see “Can Targeted PSMA PET/CT-Guided Radiotherapy Have an Impact for Oligometastatic Prostate Cancer?,” “Can 18F-Flotufolastat Bolster Detection of PCa Recurrence in Patients with Low PSA Levels After Radical Prostatectomy?” and “Optimal Timing and Frequency of Imaging Agents Used in the Detection and Characterization of Oligometastatic Prostate Cancer.”)
In regard to study limitations, the authors acknowledged the retrospective study design as well as the lack of standardized imaging and ADT protocols.
