Long-Lasting Palliation of Bone Oligometastatic Prostate Cancer After Repeated Stereotactic Body Radiotherapy

Background: Oligometastatic disease has emerged as a distinct clinical state, with a tumor burden intermediate between localized and extensive systemic disease. Oligometastatic prostate cancer has generally been classified as ≤3 metastases in bone or lymph nodes only. Improvements in diagnostic modalities such as functional imaging allow a greater frequency of oligometastases diagnosis. Selected bone oligometastatic prostate cancer patients can be treated with metastasis-directed stereotactic body radiotherapy (SBRT) rather than androgen deprivation therapy (ADT). We describe a case representative of this scenario. Case Report: A 72-year-old male underwent surgery and salvage radiotherapy for a Gleason score 7 (3+4) adenocarcinoma confined in the prostate but with microscopic-positive surgical margins. Eight months after the end of radiotherapy, bone metastasis was diagnosed and treated with SBRT only because the patient refused ADT. In the subsequent 10 years, 6 more courses of SBRT were administered for new bone oligometastases encountered during follow-up. Neither local recurrence nor toxicity was observed after SBRT treatments. The patient, who is now 83 years old, has a Karnofsky Performance Status score of 90% and has preserved a satisfactory potentia coeundi. Conclusion: SBRT is a promising treatment for patients with bone oligometastatic prostate cancer, providing a high control rate within the irradiated volume and low toxicity. The ability to administer consecutive SBRT courses when new bone oligometastases are encountered in other sites can delay initiation of ADT. This case report reflects emerging trends for bone oligometastases treatment with metastasis-directed radiotherapy.