Fatih Özcan, Esra İlgün
Background: Penile metastases (PMs) from prostate adenocarcinoma are rare manifestations of advanced disease and are often associated with significant morbidity. Optimal local management strategies remain undefined due to limited published data. Case Presentation: A 65-year-old man with metastatic prostate adenocarcinoma presented with severe penile pain, with a Visual Analog Scale (VAS) score of 8/10. Ga-68 PSMA PET/CT imaging revealed intense focal uptake in the corpus of the penis, consistent with metastatic involvement. Palliative radiotherapy was delivered with a Radixact® helical tomotherapy system, delivering a total dose of 25 Gy in 10 fractions. At three months post-treatment, the VAS score decreased to 2/10. A six-month follow-up Ga-68 PSMA PET/CT demonstrated complete resolution of pathological Ga-68 PSMA expressions in penile metastasis, consistent with a complete response to treatment. The patient remained clinically stable with sustained pain control for nine months. Conclusion: Palliative radiotherapy delivered at a dose of 25 Gy in 10 fractions achieved durable pain relief and complete resolution of pathological Ga-68 prostate-specific membrane antigen (PSMA) uptake within the penile metastasis, consistent with a complete local response to treatment, in this rare case of penile metastasis from prostate cancer. Ga-68 PSMA PET/CT played a pivotal role by facilitating a non-invasive diagnosis in a highly sensitive anatomical region without the need for an invasive biopsy, enabling accurate delineation of gross tumor volume (GTV) for precise radiotherapy planning, and providing an objective assessment of treatment response during follow-up. Image-guided conformal radiotherapy using helical tomotherapy may represent a feasible and effective organ-preserving option for symptom palliation in selected patients. However, further clinical evidence is required to better define the role of molecular imaging-guided radiotherapy in the management of this rare clinical entity.