Importance of the correct assessment of bone fractures in the clinical management of metastatic castration-resistant prostate cancer treated with radium-223: A case report

Patients who undergo radium-223 treatment for metastatic castration-resistant prostate cancer (mCRPC) generally have a long history of androgen deprivation therapy and/or steroid therapy, which leads to bone loss and causes osteoporosis. Notably, Osteoporosis in combination with metastatic bone disease increases the risk of bone fracture. An 84-year-old man with multi-metastatic bone CRPC underwent six administrations of intravenous radium-223, which induced a good biochemical and clinical response. However, two months following the treatment, the patient reported acute pain localized to the lumbar spine mimicking bone progression disease and presented with stable prostate-specific antigen levels. A prostate-specific membrane antigen-positron emission tomography scan showed no tracer uptake in that site, whereas a magnetic resonance imaging scan and subsequent vertebral biopsy confirmed the absence of cancer progression and showed the presence of vertebral crushing of L4-L5, which was probably due to an osteoporotic process. The patient had never received bisphosphonate therapy and refused it during alpha-emitting therapy with radium-223. The osteoporotic process, in association with metastatic bone disease, more easily leads to bone fractures that have an important impact on performance status, quality of life and prognosis quoad vitam in patients with advanced prostate cancer. Use of bisphosphonates or anti-RANKL antibody appears to be effective in improving bone mineral density. Notably, patients with multi-metastatic bone disease who undergo radium-223 therapy should be treated in conjunction with anti-osteoporotic therapy (bisphosphonates or anti-RANKL antibody) and adequate calcium and vitamin D supplementation. Early recognition and differentiation of osteoporotic processes when determining the progression of cancer-associated bone disease is crucial in evaluating the response to radium-223 therapy and, consequently, for further therapeutic decision making.