Carcinomas like prostate cancer possess notable bony tropism and can metastasize to the lumbar‐sacral spine and pelvis, draining through the pelvic plexus of the lumbar region. Approximately 90% of patients with advanced prostate cancer develop bone metastasis, the spine being the most common site. Manifestations of metastatic prostate cancer include weight loss and loss of appetite; bone pain, with or without pathologic fracture; and lower-extremity pain and edema. Urinary symptoms are also common. Other physical examination findings are adenopathy, bony tenderness, and lower-extremity edema, as seen in the present case.
Radiologic findings of bone metastases can mimic Paget disease, and even though bone metastases are blastic, lytic lesions may develop and cause pathologic fractures. Such fractures must be distinguished from osteoporotic fractures that can occur after prolonged luteinizing hormone–releasing hormone therapy. Also included in the differential of the present case are lymphomas, which can manifest as pelvic masses and bone lesions and have been reported with prostate cancer. However, considering the patient's history, physical examination, and lab results, bone metastasis is the most likely diagnosis.
Bone imaging should be performed for any patient with suspected bone metastases; specifically, multiparametric MRI outperforms bone scan and targeted x-rays for detection of bone metastases. Because activity in the bone scan may not be observed until 5 years after micrometastasis has occurred, negative bone scan results cannot be used to definitively exclude metastasis.
The alpha emitter radium-223 is a category 1 option to treat symptomatic bone metastases (but should not be used in patients with visceral metastases). It is not recommended for use in combination with docetaxel or any other systemic therapy but may be used with androgen-deprivation therapy (ADT), as studies have suggested that the addition of ADT improves progression-free survival in patients with castrate-resistant prostate cancer with metastasis. Concomitant use of denosumab or zoledronic acid is also recommended.
Kyle A. Richards, MD, Assistant Professor, Department of Urology, University of Wisconsin-Madison; Chief of Urology, William S. Middleton Memorial VA Hospital, Madison, Wisconsin
Kyle A. Richards, MD, has disclosed no relevant financial relationships