Management Of Treatment-induced Bone Loss Research Articles

Advances in the Therapy of Prostate Cancer–Induced Bone Disease: Current Insights and Future Perspectives on the RANK/RANKL Pathways

Abstract Context Prostate cancer (PCa) cells are characterised by an exquisite tropism for the bone, which translates into one of the highest rates of bone metastases and skeletal morbidity. New, effective treatments have emerged from a better understanding of the physiopathology of bone metastases. Objective To summarise current insights and future perspectives in the therapy of PCa-induced bone disease. Evidence acquisition This manuscript is based on presentations given at a satellite symposium held at the 2nd World Congress on Controversies in Urology (CURy) in Lisbon, Portugal. Data were retrieved from original and recent review papers on PCa-induced bone disease. Evidence synthesis In normal, healthy bone, there is a balance between bone resorption and bone formation through the coordinated activity of osteoclasts and osteoblasts. The receptor activator of nuclear factor-κB ligand (RANKL) is an essential mediator of osteoclast formation, function, and survival. The RANKL pathway represents a therapeutic target for osteoclast-induced bone destruction in pathologic conditions, including treatment-induced bone loss and metastatic cancer. Based on a multicentre, randomised, open-label, active-controlled phase 2 trial, denosumab, a fully human monoclonal antibody against RANKL, reduced the incidence of skeletal morbidity in patients with bone metastases from PCa, breast cancer, or other neoplasms. Conclusions In a phase 2 clinical study, denosumab reduced skeletal-related events in patients with bone metastases from PCa. In addition, the potential role of denosumab in the management of treatment-induced bone loss and the prevention of bone metastases is currently under investigation.

Current management of treatment-induced bone loss in women with breast cancer treated in the United Kingdom

New therapeutic options in breast cancer have improved survival but consequently increase the relevance of late complications. Ovarian suppression/ablation and aromatase inhibitors (AI) in the adjuvant setting have improved outcome, but have clinically important adverse effects on bone health. However, investigation and management of cancer treatment-induced bone loss (CTIBL) is poorly defined with no national guidance. In 2004, a questionnaire was sent to over 500 breast surgeons and oncologists who treat breast cancer within the United Kingdom. The questionnaire evaluated access to bone densitometry and specialist expertise as well as attitudes to investigation of CTIBL and anticipated changes in the use of AI for postmenopausal early breast cancer. A total of 354 completed questionnaires were received, 47 from clinicians not currently treating breast cancer. Of the 307 evaluable questionnaires, 164 (53%) were from breast surgeons, 112 (36%) from clinical oncologists and 31 (10%) from medical oncologists. Although most respondents recognised that CTIBL was the responsibility of the treating breast team, investigations for CTIBL are limited even though most had adequate access to bone densitometry; 98 (32%) had not requested a DXA scan in the last 6 months and 224 (73%) had requested fewer than five scans. In all, 235 (76%) were not routinely investigating patients on AI for bone loss. A total of 277 (90%) felt that their practice would benefit from national guidelines to manage these patients, and the majority (59%) had little or no confidence in interpreting DXA results and advising on treatment. This questionnaire has highlighted clear deficiencies in management of CTIBL in early breast cancer. The development of national guidelines for the management of these patients and educational initiatives for breast teams are urgently required.

Bone loss and the aromatase inhibitors

The increasing use of systemic adjuvant therapies has considerably improved the prognosis from early breast cancer. However, some of these therapies affect bone metabolism, resulting in osteoporosis. Aromatase inhibitors lower circulating oestrogen levels to almost unrecordable levels in postmenopausal women, predisposing them to bone loss with an increase in fracture risk. Ongoing clinical trials are favouring the use of the aromatase inhibitors over tamoxifen and this may advocate greater use of these drugs in the future. Strategies for the identification and management of treatment-induced bone loss are currently being defined.

The role of bisphosphonates in breast and prostate cancers.

Bisphosphonate drugs are a group of pyrophosphate analogues which bind avidly to hydroxyapatite bone mineral surfaces and their major action is to inhibit osteoclast activity and thus bone resorption. In oncology, their role in metastatic bone disease is well established, but there is increasing interest in their potential role in preventing and treating cancer-induced bone loss and their possible anti-tumour effects. Metastatic bone disease is associated with a variety of skeletal complications, including pathologic fractures, bone pain, impaired mobility, spinal cord compression and hypercalcaemia. Intravenous bisphosphonates, particularly zoledronic acid, in conjunction with rehydration, are now established as the treatment of choice for hypercalcaemia. For treatment of bone pain, it has also been shown that bisphosphonates can be an effective supplementary approach to radiotherapy. In breast cancer and myeloma, bisphosphonates have now become part of standard therapy to treat and prevent skeletal-related events (SRE) and, until recently, treatment was largely with intravenous pamidronate or oral clodronate. However, large, randomised, multicentre trials using intravenous administration of the highly potent bisphosphonate zoledronic acid every 3-4 weeks have recently demonstrated a reduction of 20% in the risk of developing an SRE compared with pamidronate for patients with breast cancer. Moreover, these trials have demonstrated, for the first time, that a bisphosphonate significantly reduces the occurrence of skeletal events in hormone-refractory prostate cancer and in non-small cell lung cancer and a range of other solid tumours. Investigations into the potential of the relatively low potency bisphosphonate, clodronate, for the prevention of bone metastases in breast cancer have produced conflicting data. Further large, randomised studies with clodronate and zoledronic acid are planned and until the results are available it is not possible to identify a definite adjuvant role for bisphosphonates. Evidence is accumulating in vitro that bisphosphonates are also able to directly affect tumour cells, in addition to their effects on osteoclasts, with zoledronic acid being particularly potent. Over recent decades there has been a significant improvement in cure rates and survival times in certain cancers and the use of chemotherapy and hormone therapy has expanded greatly, leading to increasing numbers of long-term survivors who have received these treatments. Management of treatment-induced bone loss is therefore assuming a greater importance and bisphosphonates represent an attractive treatment option in such patients. Several placebo-controlled trials using oral clodronate, oral risedronate, intravenous pamidronate and intravenous zoledronic acid have all now demonstrated benefits in reducing the loss in bone mineral density.