Should All Breast Cancer Patients with Symptomatic Bone Metastases be Treated with Bisphosphonates? The Case in Support☆☆This debate was presented at the Tenth Annual Conference on ‘The Science and Art of Pain and Symptom Management’ held in Toronto, Canada on 14–15 November, 2003. Your views are welcomed in a letter to the Editor for publication in the correspondence section of the Journal

Treatment Options for Breast Cancer and Bone Metastases

The most common destination for breast cancer metastases is bone. If bone metastases are detected, treatment algorithms should include the continuation of cytoreductive therapy with the addition of treatment to counter skeletal-related events, including bone pain. The range of current treatment options includes bisphosphonates, surgical intervention to improve structural integrity and palliative focal radiotherapy. This article focuses on the role of bisphosphonate therapy in metastatic breast cancer. Bisphosphonate therapy significantly reduces the impact of skeletal-related events, reduces bone pain and increases patient quality of life. Our current understanding is that bisphosphonates may also disrupt the metastatic process and reduce the development of bone lesions. Ultimately, this may lead to further expansion of bisphosphonate-based therapy in the future.

Too Much, Too Little, Too Late to Start Again? Assessing the Efficacy of Bisphosphonates in Patients with Bone Metastases from Breast Cancer

The diagnosis of bone metastases can be a devastating occurrence for any woman with breast cancer. In this setting, bone metastases can result in skeletal-related events (SREs) such as pathologic fracture, spinal cord compression, and hypercalcemia. Several trials have confirmed the ability of bisphosphonates to reduce or delay these skeletal complications, and they should now be considered standard care for these women. The analysis of SREs is the typical primary end point in bisphosphonate studies. While not undermining their importance, the definition of SREs does not include complications important to patients, such as pain and immobility. It is these symptoms that are most frequently reported by patients, and bone pain and quality of life (QoL) are often measured as secondary end points in these trials. Bone pain and QoL measures are not standardized and are difficult to compare among patient populations. We do not yet know the true efficacy of bisphosphonates as analgesics or how they impact QoL. This paper reviews the current efficacy measures used in recent bisphosphonate trials and discusses their benefits and limitations. It also explores the role of bone biomarkers and their potential use in monitoring treatment response.

Can bone markers guide more effective treatment of bone metastases from breast cancer?

Bone metastases are a common problem for breast cancer patients, causing significant disease-related morbidity and mortality. Bisphosphonates and other cancer therapies can assist in managing these patients. However, assessing treatment efficacy in bone metastases is hampered by the inability to accurately measure disease response within a clinically desirable time frame. Bone-specific biochemical markers, notably type I collagen telopeptide cross-link by-products such as N-telopeptide (NTx) and C-telopeptide (CTx), have been shown to be effective tools for assessing the severity and extent of bone metastases, and the response to bisphosphonates. Elevated NTx levels correlate with adverse clinical outcomes. Normalization of NTx and CTx excretion rates are associated with relief of symptoms and a reduced incidence of skeletal-related events (SRE). This review discusses the expanding role of these bone markers in guiding treatment of bone metastases from breast cancer.

Perspectives on the future of bisphosphonate use in breast cancer patients

Bisphosphonates are effective for reducing the skeletal complications of metastatic breast cancer. Current treatment guidelines tend to recommend starting bisphosphonates at the time of diagnosis of bone metastases and continuing indefinitely or until the patients' performance status declines substantially. While meta-analyses of clinical trials have suggested that treatment should continue for at least 6 months to reduce skeletal-related events, few data exist on alternative strategies to optimize therapy. Other indications for bisphosphonates in the management of breast cancer include managing reduced bone mineral density in patients with early stage disease. In addition, because of considerable preclinical and clinical evidence that they may have direct antitumor actions, bisphosphonates are being tested as adjuvant therapy for early stage breast cancer in a number of large clinical trials.

Assessment of therapeutic response in patients with metastatic bone disease

Metastatic bone disease is common in cancer patients and causes substantial disease-related morbidity and mortality. However, several effective treatments are available for the management of these patients. Bisphosphonates, which inhibit osteoclast-mediated resorption of bone matrix, are especially important because they decrease the incidence of skeletal-related events in many tumour types and can complement antineoplastic therapies. At present, assessment of treatment for bone metastases is hindered by a lack of effective, rapid methods to measure disease response. We discuss the difficulties of current measures of response assessment and describe the development of new radiological and biochemical markers of bone metastases. Assays that detect type I collagen telopeptides as markers of bone resorption seem to be most promising at present.