Meta-analysis of clodronate and breast cancer survival

Fracture risk and assessment in adults with cancer

Individuals with cancer face unique risk factors for osteoporosis and fractures. Clinicians must consider the additive effects of cancer-specific factors, including treatment-induced bone loss, and premorbid fracture risk, utilizing FRAX score and bone mineral densitometry when available. Pharmacologic therapy should be offered as per cancer-specific guidelines, when available, or local general osteoporosis guidelines informed by clinical judgment and patient preferences. Our objective was to review and summarize the epidemiologic burden of osteoporotic fracture risk and fracture risk assessment in adults with cancer, and recommended treatment thresholds for cancer treatment-induced bone loss, with specific focus on breast, prostate, thyroid, gynecological, multiple myeloma, and hematopoietic stem cell transplant. This narrative review was informed by PubMed searches to July 25, 2022, that combined terms for cancer, stem cell transplantation, fracture, bone mineral density (BMD), trabecular bone score, FRAX, Garvan nomogram or fracture risk calculator, QFracture, prediction, and risk factors. The literature informs that cancer can impact bone health in numerous ways, leading to both systemic and localized decreases in BMD. Many cancer treatments can have detrimental effects on bone health. In particular, hormone deprivation therapies for hormone-responsive cancers such as breast cancer and prostate cancer, and hematopoietic stem cell transplant for hematologic malignancies, adversely affect bone turnover, resulting in osteoporosis and fractures. Surgical treatments such as hysterectomy with bilateral salpingo-oophorectomy for gynecological cancers can also lead to deleterious effects on bone health. Radiation therapy is well documented to cause localized bone loss and fractures. Few studies have validated the use of fracture risk prediction tools in the cancer population. Guidelines on cancer-specific treatment thresholds are limited, and major knowledge gaps still exist in fracture risk and fracture risk assessment in patients with cancer. Despite the limitations of current knowledge on fracture risk assessment and treatment thresholds in patients with cancer, clinicians must consider the additive effects of bone damaging factors to which these patients are exposed and their premorbid fracture risk profile. Pharmacologic treatment should be offered as per cancer-specific guidelines when available, or per local general osteoporosis guidelines, in accordance with clinical judgment and patient preferences.

Bisphosphonates and breast cancer survival: a meta-analysis and trial sequential analysis of 81508 participants from 23 prospective epidemiological studies

BACKGROUND

We assessed the effect of bisphosphonates (BPs) on breast cancer (BCa) patient survival and explored how long the effect can persist after treatment.

METHODS

We performed a meta-analysis and trial sequential analysis (TSA) of prospective studies including randomized controlled trials (RCTs) and cohort studies. We performed extensive sensitivity analyses to assess the robustness of the findings.

RESULTS

Seventeen RCTs and eight cohorts with 81508 BCa patients were identified. A significant beneficial effect of BPs on BCa survival was found (RR, 0.725; 95% CI, 0.627-0.839), and the TSA results also suggested firm evidence for this beneficial effect. Both summarized results from RCTs and cohorts provided firm evidence for this effect, although the effect estimates were stronger from cohorts than RCTs (RR, 0.892; 95% CI, 0.829-0.961; 0.570; 95% CI, 0.436-0.745; respectively). This beneficial effect was confirmed for bone-metastases (RR, 0.713; 95% CI, 0.602-0.843) and postmenopausal women (RR, 0.737; 95% CI, 0.640-0.850). Importantly, our results demonstrated that this beneficial effect was retained at least 1-2 years after treatment completion (RR, 0.780; 95% CI, 0.638-0.954) and could persist for up to more than 4 years after treatment completion (RR, 0.906; 95% CI, 0.832-0.987). Extensive sensitivity analyses showed the robustness of our results. The GRADE quality of evidence was generally judged to be moderate to high.

CONCLUSIONS

The present study provides firm evidence for a significant beneficial effect of BPs on BCa survival in patients with early-stage BCa, and this effect was retained at least 1-2 years after BP treatment completion.

Mechanisms of Macrophage Plasticity in the Tumor Environment: Manipulating Activation State to Improve Outcomes

Macrophages are a specialized class of innate immune cells with multifaceted roles in modulation of the inflammatory response, homeostasis, and wound healing. While developmentally derived or originating from circulating monocytes, naïve macrophages can adopt a spectrum of context-dependent activation states ranging from pro-inflammatory (classically activated, M1) to pro-wound healing (alternatively activated, M2). Tumors are known to exploit macrophage polarization states to foster a tumor-permissive milieu, particularly by skewing macrophages toward a pro-tumor (M2) phenotype. These pro-tumoral macrophages can support cancer progression by several mechanisms including immune suppression, growth factor production, promotion of angiogenesis and tissue remodeling. By preventing the adoption of this pro-tumor phenotype or reprogramming these macrophages to a more pro-inflammatory state, it may be possible to inhibit tumor growth. Here, we describe types of tumor-derived signaling that facilitate macrophage reprogramming, including paracrine signaling and activation of innate immune checkpoints. We also describe intervention strategies targeting macrophage plasticity to limit disease progression and address their implications in cancer chemo- and immunotherapy.

Appraising the quality of meta-analysis for breast cancer treatment in the adjuvant setting: A systematic review

INTRODUCTION

Breast cancer is the tumor with highest incidence in women worldwide and adjuvant treatment is extremely important to achieve disease control. Given the relevance of systematic reviews, their rigor should be warranted to avoid biased conclusions. Our objective was to investigate the methodological quality of meta-analysis of early breast cancer adjuvant treatment.

MATERIAL AND METHODS

Comprehensive searches were performed using electronic databases from 1/1/2007 to 11/12/2018. All studies identified as a systematic review with meta-analysis investigating the efficacy of breast cancer adjuvant treatments were included. Two reviewers independently assessed titles and abstracts, then full-texts for eligibility. Quality was assessed using the Assessing the Methodological Quality of Systematic Reviews (AMSTAR) version 2 tool.

RESULTS

Of 950 citations retrieved, 66 studies (7.0%) were deemed eligible. Methodological quality was highly variable, median AMSTAR score 8.5 (IQR 7-9.5) and range 0-16. There was a weak positive correlation between journal impact factor and AMSTAR score (r = 0.17) and citation rate and AMSTAR score (r = 0.16). Cochrane Systematic Reviews were of higher quality than reviews from other journals. Overall confidence was critically low for 61 (92.4%) studies, and the least well-reported domains were the statement of conflict of interest and funding source for the included studies (4.6%), the report of a pre-defined study protocol (15.2%), and the description of details of excluded studies (6.1%).

CONCLUSIONS

Our findings reinforce concerns about the design, conduction and interpretation of meta-analysis in current literature. Methodological quality should be carefully considered and journal editors, decision makers and readers in general, must follow a critical approach to this studies.

The Biology of Bone Metastasis

Bone metastasis, or the development of secondary tumors within the bone of cancer patients, is a debilitating and incurable disease. Despite its morbidity, the biology of bone metastasis represents one of the most complex and intriguing of all oncogenic processes. This complexity derives from the intricately organized bone microenvironment in which the various stages of hematopoiesis, osteogenesis, and osteolysis are jointly regulated but spatially restricted. Disseminated tumor cells (DTCs) from various common malignancies such as breast, prostate, lung, and kidney cancers or myeloma are uniquely primed to subvert these endogenous bone stromal elements to grow into pathological osteolytic or osteoblastic lesions. This colonization process can be separated into three key steps: seeding, dormancy, and outgrowth. Targeting the processes of dormancy and initial outgrowth offers the most therapeutic promise. Here, we discuss the concepts of the bone metastasis niche, from controlling tumor-cell survival to growth into clinically detectable disease.

Management of Aromatase Inhibitor-Associated Bone Loss (AIBL) in postmenopausal women with hormone sensitive breast cancer: Joint position statement of the IOF, CABS, ECTS, IEG, ESCEO IMS, and SIOG

BACKGROUND

Several guidelines have been reported for bone-directed treatment in women with early breast cancer (EBC) for averting fractures, particularly during aromatase inhibitor (AI) therapy. Recently, a number of studies on additional fracture related risk factors, new treatment options as well as real world studies demonstrating a much higher fracture rate than suggested by randomized clinical controlled trials (RCTs). Therefore, this updated algorithm was developed to better assess fracture risk and direct treatment as a position statement of several interdisciplinary cancer and bone societies involved in the management of AI-associated bone loss (AIBL).

PATIENTS AND METHODS

A systematic literature review identified recent advances in the management of AIBL. Results with individual agents were assessed based on trial design, size, follow-up, and safety.

RESULTS

Several fracture related risk factors in patients with EBC were identified. Although, the FRAX algorithm includes fracture risk factors (RF) in addition to BMD, it does not seem to adequately address the effects of AIBL. Several antiresorptive agents can prevent and treat AIBL. However, concerns regarding compliance and long-term safety remain. Overall, the evidence for fracture prevention is strongest for denosumab 60 mg s.c. every 6 months. Additionally, recent studies as well as an individual patient data meta-analysis of all available randomized trial data support additional anticancer benefits from adjuvant bisphosphonate treatment in postmenopausal women with a 34% relative risk reduction in bone metastasis and 17% relative risk decrease in breast cancer mortality that needs to be taken into account when advising on management of AIBL.

CONCLUSIONS

In all patients initiating AI treatment, fracture risk should be assessed and recommendation with regard to exercise and calcium/vitamin D supplementation given. Bone-directed therapy should be given to all patients with a T-score<-2.0 or with a T-score of <-1.5 SD with one additional RF, or with ≥2 risk factors (without BMD) for the duration of AI treatment. Patients with T-score>-1.5 SD and no risk factors should be managed based on BMD loss during the first year and the local guidelines for postmenopausal osteoporosis. Compliance should be regularly assessed as well as BMD on treatment after 12 - 24 months. Furthermore, because of the decreased incidence of bone recurrence and breast cancer specific mortality, adjuvant bisphosphonates are recommended for all postmenopausal women at significant risk of disease recurrence.

Bisphosphonate and risk of cancer recurrence: protocol for a systematic review, meta-analysis and trial sequential analysis of randomised controlled trials

INTRODUCTION

No consensus exists on the associations between adjuvant treatment with bisphosphonates and cancer recurrence risk among patients with primary early-stage cancers. We plan to perform a comprehensive systematic review, study-level meta-analysis and trial sequential analysis of randomised controlled trials to comprehensively summarise evidence of the bisphosphonate treatment for difference cancers.

METHODS AND ANALYSES

We will report our results according to the PRISMA guideline. The primary outcomes include any cancer recurrence and bone metastasis and secondary outcomes include events of local recurrence, regional recurrence or non-skeletal distant metastasis, disease-free survival and overall survival. We will perform systematic electronic searches and other manual searches. To be conservative, all statistical analyses will be conducted with random-effects models. Cumulative meta-analyses and trial sequential analyses will be performed to assess whether and when firm evidence is reached. Various sensitivity analyses and rigid publication bias analyses will be performed to challenge the consistency and robustness of results. We will also grade the quality of evidence with the GRADE system.

ETHICS AND DISSEMINATION

Ethical approval is not required in this study. The findings will be submitted for publication in a peer-reviewed journal and also presented at relevant national and international conferences.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42014014699.

A multi-targeted approach to treating bone metastases

The treatment of bone-metastatic cancer now takes advantage of the unique biology of this clinical state. The complex interplay between the cancer cells and the bone microenvironment leads to a host of therapeutic targets, with agents in various stages of clinical use or study. Targets include interactions between the cancer cells and osteoclasts, osteoblasts, endothelial cells, stromal cells, hematopoietic progenitor cells, cells of the immune system, and the bone matrix. Efforts at understanding specific mechanisms of drug resistance in the bone are also ongoing. Successful clinical outcomes will be the result of co-targeting and interrupting the various tumor-supportive elements and cooperating pathways at the level of the tumor cell, the primary and metastatic microenvironments, and systemic cancer effects, leading to a "scaled network disruption" to undermine the disease state.

Stabilization of bone marrow infiltration by metastatic breast cancer with continuous doxorubicin

Complete bone marrow infiltration with profound pancytopenia is very uncommon in breast cancer. Bone marrow metastasis can frequently occur following development of metastatic breast cancer. However, bone marrow failure as the herald of this disease is not typically seen. Very limited data exists as to the safest and most efficacious manner to treat patients with profound pancytopenia due to metastatic solid tumor involvement. In this case, the patient’s thrombocytopenia was particularly worrisome, requiring daily platelet transfusions. There was also concern that cytotoxic chemotherapy would exacerbate the patient’s thrombocytopenia and increase bleeding risk. The patient’s dramatic response to chemotherapy with full platelet recovery is also highly unusual. For our patient, continuous doxorubicin successfully “unpacked” the bone marrow despite a low baseline platelet level, and without increasing the need for more frequent platelet transfusion or risk of catastrophic bleeding. Given the rarity of this presentation, it is currently unknown if the majority of similar patients experience near full recovery of hematopoietic function after initiation of appropriate systemic treatment for metastatic disease.

Reverse-phase protein array for prediction of patients at low risk of developing bone metastasis from breast cancer

BACKGROUND

A biomarker that predicts bone metastasis based on a protein laboratory assay has not been demonstrated. Reverse-phase protein array (RPPA) enables quantification of total and phosphorylated proteins, providing information about their functional status. The aim of this study was to identify bone-metastasis-related markers in patients with primary breast cancer using RPPA analysis.

PATIENTS AND METHODS

Tumor samples were obtained from 169 patients with primary invasive breast carcinoma who underwent surgery. The patients were categorized by whether they developed breast cancer bone metastasis (BCBM) during follow-up. Clinical characteristics and protein expression by RPPA were compared and verified by leave-one-out cross-validation.

RESULTS

Lymph node status (p = .023) and expression level of 22 proteins by RPPA were significantly correlated with BCBM in logistic regression analysis. These variables were used to build a logistic regression model. After filtering the variables through a stepwise algorithm, the final model, consisting of 8 proteins and lymph node status, had sensitivity of 30.0%, specificity of 90.5%, positive predictive value of 30.0%, and negative predictive value of 90.5% in the cross-validation. Most of the identified proteins were associated with cell cycle or signal transduction (CDK2, CDKN1A, Rb1, Src, phosphorylated-ribosomal S6 kinase, HER2, BCL11A, and MYH11).

CONCLUSION

Our validated model, in which the primary tumor is tested with RPPA, can predict patients who are at low risk of developing BCBM and thus who likely would not benefit from receiving a bisphosphonate in the adjuvant setting. Clinical trials excluding these patients have the potential to clarify the benefit of bisphosphonates in the adjuvant setting.

Prevention of Bone Metastases in Breast Cancer Patients. Therapeutic Perspectives

One in four breast cancer patients is at risk of developing bone metastases in her life time. The early prevention of bone metastases is a crucial challenge. It has been suggested that the use of zoledronic acid (ZOL) in the adjuvant setting may reduce the persistence of disseminated tumor cells and thereby might improve outcome, specifically in a population of patients with a low estrogen microenvironment. More recently, the results of a large meta-analysis from 41 randomized trials comparing a bisphosphonate (BP) to placebo or to an open control have been presented at the 2013 San Antonio Breast Cancer Meeting. Data on 17,016 patients confirm that adjuvant BPs, irrespective of the type of treatment or the treatment schedule and formulation (oral or intra-venously (IV)), significantly reduced bone recurrences and improved breast cancer survival in postmenopausal women. No advantage was seen in premenopausal women. BPs are soon likely to become integrated into standard practice. Published data on the mechanisms involved in tumor cell seeding from the primary site, in homing to bone tissues and in the reactivation of dormant tumor cells will be reviewed; these might offer new ideas for innovative combination strategies.

The anti-tumour effects of zoledronic acid

Bone is the most common site for metastasis in patients with solid tumours. Bisphosphonates are an effective treatment for preventing skeletal related events and preserving quality of life in these patients. Zoledronic acid (ZA) is the most potent osteoclast inhibitor and is licensed for the treatment of bone metastases. Clodronate and pamidronate are also licensed for this indication. In addition, ZA has been demonstrated to exhibit antitumour effect. Direct and indirect mechanisms of anti-tumour effect have been postulated and at many times proven. Evidence exists that ZA antitumour effect is mediated through inhibition of tumour cells proliferation, induction of apoptosis, synergistic/additive to inhibitory effect of cytotoxic agents, inhibition of angiogenesis, decrease tumour cells adhesion to bone, decrease tumour cells invasion and migration, disorganization of cell cytoskeleton and activation of specific cellular antitumour immune response. There is also clinical evidence from clinical trials that ZA improved long term survival outcome in cancer patients with and without bone metastases. In this review we highlight the preclinical and clinical studies investigating the antitumour effect of bisphosphonates with particular reference to ZA.

Treatment and Prevention of Bone Metastases from Breast Cancer: A Comprehensive Review of Evidence for Clinical Practice

Bone is the most common site of metastasis from breast cancer. Bone metastases from breast cancer are associated with skeletal-related events (SREs) including pathological fractures, spinal cord compression, surgery and radiotherapy to bone, as well as bone pain and hypercalcemia, leading to impaired mobility and reduced quality of life. Greater understanding of the pathophysiology of bone metastases has led to the discovery and clinical utility of bone-targeted agents such as bisphosphonates and the receptor activator of nuclear factor kappa-B ligand (RANK-L) antibody, denosumab. Both are now a routine part of the treatment of breast cancer bone metastases to reduce SREs. With regards to prevention, there is no evidence that oral bisphosphonates can prevent bone metastases in advanced breast cancer without skeletal involvement. Several phase III clinical trials have evaluated bisphosphonates as adjuvant therapy in early breast cancer to prevent bone metastases. The current published data do not support the routine use of bisphosphonates in unselected patients with early breast cancer for metastasis prevention. However, significant benefit of adjuvant bisphosphonates has been consistently observed in the postmenopausal or ovarian suppression subgroup across multiple clinical trials, which raises the hypothesis that its greatest anti-tumor effect is in a low estrogen microenvironment. An individual patient data meta-analysis will be required to confirm survival benefit in this setting. This review summarizes the key evidence for current clinical practice and future directions.

Randomized feasibility study of de-escalated (every 12 wk) versus standard (every 3 to 4 wk) intravenous pamidronate in women with low-risk bone metastases from breast cancer

OBJECTIVES

Despite substantial variability in individual risk of skeletal complications, patients with metastatic bone disease are treated with bisphosphonates at the same dose and dosing interval. This study assessed the feasibility of conducting a randomized trial of less frequent bisphosphonate administration in women with breast cancer and low-risk bone metastases.

METHODS

A randomized feasibility study was conducted. Patients receiving intravenous bisphosphonates for ≥3 months and with low-risk baseline serum C-telopeptide (CTx) levels (<600 ng/L) were assigned to pamidronate 90 mg intravenously every 3 to 4 weeks (control) or every 12 weeks (de-escalated). CTx, bone alkaline phosphatase, and pain scores (Brief Pain Inventory and Functional Assessment of Cancer Therapy-Bone Pain) were collected every 12 weeks for 48 weeks.

RESULTS

Fifty-four patients were approached, 44 consented, and 38 were randomized. Median age was 55 (range, 29 to 77) and median baseline CTx was 163 ng/L (range, 10 to 526). Fourteen control group participants (73.7%) and 13 de-escalated group participants (68.4%) maintained CTx in the low-risk range (P=0.64). All patients changing to higher-risk range had progressive extraskeletal disease. Compared with the control group, there was a time-dependent increase in CTx in the de-escalated group. There were no significant differences in bone alkaline phosphatase, Brief Pain Inventory, or Functional Assessment of Cancer Therapy-Bone Pain.

CONCLUSIONS

It is feasible to conduct randomized trials of de-escalated pamidronate in low-risk women treated with ≥3 months of prior bisphosphonate therapy. De-escalated scheduling satisfied our predefined definition of noninferiority compared with 3- to 4-weekly treatment. Larger trials should assess whether increasing CTx levels with de-escalated therapy lead to higher rates of skeletal complications.

Adjuvant bisphosphonates in breast cancer: has the time come?

SUMMARY Bone metabolism is highly affected by changes in ovarian function, which is a common consequence of the treatment of breast cancer patients. Osteopenia and osteoporosis increase the risk of fractures, which are associated with profound loss in quality of life. Bisphosphonates are used with the objective of preventing bone loss in patients with osteoporosis, but data suggest that agents such as zoledronic acid might play a role in the prevention of metastatic disease and therefore have been evaluated in numerous randomized trials in the adjuvant setting. This review article will discuss and analyze the available data regarding the use of bisphosphonates in the adjuvant setting for breast cancer patients. It will focus on the use of bisphosphonates as anticancer agents, but will also discuss the use of these agents for the prevention of bone loss.

Bisphosphonates in the adjuvant treatment of young women with breast cancer: the estrogen rich is a poor candidate!

During the last 2 decades the role of bisphosphonates (BPs) to reduce skeletal-related events from bone metastases in breast cancer has been well defined. Several preclinical studies have strongly suggested that BPs may also provide an anti-cancer effect in early breast cancer. Indeed, the use of adjuvant BPs represents a unique approach that attempts at eradicating occult tumor micro-metastases residing in the bone marrow via targeting the bone microenvironment to render it less favorable for cancer cell growth. Although, this concept has been tested clinically for more than 15 years, no final consensus has been reached as for the routine use of BPs in the adjuvant phase of breast cancer, owing to conflicting results of randomized studies. Nevertheless, accumulating evidence from recent trials has indicated a therapeutic benefit of adjuvant BPs-particularly zoledronic acid-in women with established menopause, with no or perhaps detrimental effects in premenopausal women. Indeed, this hypothesis has opened a new chapter on the role of estrogen-poor microenvironment as a potential pre-requisite for the anti-tumor effects of BPs in the adjuvant phase of breast cancer. In this review, we will emphasize the biological rational of using BPs to target bone microenvironment in patients with early breast cancer and we will explore mechanistic differences; related to bisphosphonates effects in premenopausal versus postmenopausal women and how the endocrine environment would influence the anticancer potential of these compounds.

Oral adjuvant clodronate therapy could improve overall survival in early breast cancer: results from an updated systematic review and meta-analysis

OBJECT

The aim of this study was to evaluate the effectiveness of clodronate in the adjuvant therapy of early breast cancer on patient survival.

METHODS

We performed a literature search to identify studies that investigated the effects of clodronate treatment on early breast cancer. Random and fixed-effect meta-analytical models were used where indicated and between-study heterogeneity was assessed. The primary study end-points were overall survival. Secondary end-points were bone metastasis-free survival and non-skeletal metastasis (mainly visceral metastases) free survival.

RESULTS

Four randomised controlled trials met the inclusion criteria. Risk ratio (95% confidence interval (CI)) of overall survival was 0.84 (0.56-1.26); risk ratio (95% CI) of bone metastasis-free survival was 0.77 (0.58-1.02); risk ratio (95% CI) of non-bone metastasis-free survival was 0.89 (0.61-1.30). Outcomes after sensitivity analysis were: risk ratio (95% CI) of overall survival was 0.71 (0.52-0.96); risk ratio (95% CI) of bone metastasis-free survival was 0.70 (0.56-0.86); risk ratio (95% CI) of non-bone metastasis-free survival was 0.76 (0.64-0.92).

CONCLUSION

Compared with the control arm, adjuvant treatment with clodronate may improve the overall survival, bone metastasis-free survival and non-bone metastasis-free (mainly visceral metastases) survival in patients with early breast cancer. However, further meta-analyses involving all known randomised trials with analysis of sub-groups by age or menopausal status, accessing original trial data, should be performed.

Bisphosphonates in the adjuvant treatment of breast cancer

Bisphosphonates, as potent inhibitors of osteoclast-mediated bone resorption, significantly reduce the risk of skeletal complications in metastatic bone disease and also prevent cancer treatment-induced bone loss (CTIBL). However, more recently, there has been increasing data indicating that bisphosphonates exhibit anti-tumour activity, possibly via both indirect and direct effects, and can potentially modify the metastatic disease process providing more than just supportive care. The evidence from previous studies of an anti-tumour effect of bisphosphonates was inconclusive, with conflicting evidence from adjuvant oral clodronate trials. However, more recent trials using zoledronic acid have shown benefits in terms of disease-free and overall survival outcomes in certain subgroups, most evidently in older premenopausal women with hormone-sensitive disease treated with ovarian suppression, and in women in established menopause at trial entry. In the adjuvant setting, the use of bisphosphonates has also been focused on the prevention and treatment of CTIBL and recent guidelines have defined treatment strategies for CTIBL. The role of bisphosphonates in CTIBL in early breast cancer is well defined. There have been mixed results from large adjuvant metastasis-prevention studies of bisphosphonates, but there are strong signals from large subgroups analyses of randomised phase III trials suggesting significant anti-tumour beneficial effects in specific patient populations.

SEOM guidelines for the treatment of bone metastases from solid tumours

Bone metastases are a common and distressing effect of cancer, being a major cause of morbidity in many patients with advanced stage cancer, in particular in breast and prostate cancer. Patients with bone metastases can experience complications known as skeletal-related events (SREs) which may cause significant debilitation and have a negative impact on quality of life and functional independence. The current recommended systemic treatment for the prevention of SREs is based on the use of bisphosphonates: ibandronate, pamidronate and zoledronic acid- the most potent one- are approved in advanced breast cancer with bone metastases, whereas only zoledronic acid is indicated in advanced prostate cancer with bone metastases. The 2011 ASCO guidelines on breast cancer, recommend initiating bisphosphonate treatment only for patients with evidence of bone destruction due to bone metastases. Denosumab, a fully human antibody that specifically targets the RANK-L, has been demonstrated in two phase III studies to be superior to zoledronic acid in preventing or delaying SREs in breast and prostate cancer and non-inferior in other solid tumours and mieloma; it's convenient subcutaneous administration and the fact that does not require dose adjustment in cases of renal impairment, make this agent an attractive new therapeutic option in patients with bone metastases. Finally, in a phase III study against placebo, denosumab significantly increased the median metastasis-free survival in high risk non-metastatic prostate cancer, arising the potential role of these bone-modifying agents in preventing or delaying the development of bone metastases.

Systemic Therapy for Bone Metastases

Background

Accelerated bone loss in patients with cancer is a frequent problem that may result from invasion of the cancer to bone, paraneoplastic tumor proteins, and/or hormonal therapies utilized for cancer treatment. Patients with osteolytic bone disease from multiple myeloma and bone metastases from solid tumors may develop a vicious cycle of bone destruction involving both osteolytic and osteoblastic effects. Consequently, a variety of skeletal-related events (SREs) may occur, including pathological fractures, hypercalcemia, spinal cord compression, and the need for surgical intervention and radiation therapy.

Methods

This article reviews the results of trials that investigated the safety and efficacy of pharmacologic agents, including bisphosphonates and denosumab, for treatment of bone metastases. This analysis is derived from an assessment of the medical literature.

Results

Beneficial systemic therapies for bone metastases have been developed to decrease SREs. Possible antitumor effects of the bisphosphonates are explored. In addition, the utility of markers of bone turnover in relation to response to therapy and survival, the safety and toxicity of bone-targeted therapies, treatment guidelines, and economic considerations are also discussed.

Conclusions

Effective systemic therapies for metastatic bone disease are available. Ongoing and future research projects in this field are also presented.

Seed, soil and secreted hormones: potential interactions of breast cancer cells with their endocrine/paracrine microenvironment and implications for treatment with bisphosphonates

The process of formation of metastasis is undoubtedly inefficient, with the majority of disseminated tumour cells perishing in their metastatic environment. Their ability to survive is determined by their intrinsic abilities, with emerging evidence of the importance of cancer stem cells possessing self propagating potential, but also the interaction with the premetastatic niche, which may either help or hinder their formation into micrometastasis, thus influencing recurrence and survival in breast cancer patients. Use of the bone targeted agents bisphosphonates in the adjuvant setting has been extensively studied in large clinical trials, and demonstrated an interesting interplay with the endocrine microenvironment, with postmenopausal women or premenopausal women receiving ovarian suppression therapy gaining a survival advantage compared to pre/perimenopausal women. The interaction between the endocrine hormones and the paracrine TGFβ growth factors may provide an explanation for the differences seen according to ovarian function in the response to bisphosphonates. In this review the evidence of interplay between ovarian endocrine hormones, TGFβ paracrine growth factors and bisphosphonates will be presented, and subsequent influence on breast cancer cells in the bone pre-metastatic niche hypothesised.

Bisphosphonates and other bone agents for breast cancer

BACKGROUND

Bone is the most common site of metastatic disease associated with breast cancer (BC). Bisphosphonates inhibit osteoclast-mediated bone resorption, and novel targeted therapies such as denosumab, inhibit key pathways in the vicious cycle of bone metastases.

OBJECTIVES

To assess the effect of bisphosphonates on skeletal-related events (SREs), bone pain, quality of life (QoL), recurrence and survival in women with breast cancer with bone metastases (BCBM), advanced breast cancer (ABC) without clinical evidence of bone metastases and early breast cancer (EBC).To assess the effect of denosumab on SREs, bone pain and (QoL) in women with (BCBM).

SEARCH METHODS

We searched the Specialised Register maintained by the Cochrane Breast Cancer Group (CBCGSR), MEDLINE, EMBASE and the WHO International Cancer Trials Registry Platform (WHO ICTRP) on 30 April 2011. We conducted additional handsearching of journals and proceedings of key meetings.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing: (a) bisphosphonates and control, or different bisphosphonates in women with BCBM; (b) denosumab and bisphosphonates in women with BCBM; (c) bisphosphonates and control in women with ABC; (d) bisphosphonates and control in women with EBC; and (e) early versus delayed bisphosphonate treatment in women with EBC.

DATA COLLECTION AND ANALYSIS

Two review authors (MW and NP) independently assessed the trials and extracted the data. We collected toxicity information from the trials.

MAIN RESULTS

We included thirty-four RCTs. In nine studies (2806 patients with BCBM), comparing bisphosphonates with placebo or no bisphosphonates, bisphosphonates reduced the SRE risk by 15% (risk ratio (RR) 0.85; 95% confidence interval (CI) 0.77 to 0.94; P = 0.001). This benefit was most certain with intravenous (i.v.) zoledronic acid (4 mg) (RR 0.59; 95% CI 0.42 to 0.82); i.v. pamidronate (90 mg) (RR 0.77; 95% CI 0.69 to 0.87); and i.v. ibandronate (RR 0.80; 95% CI 0.67 to 0.96). A direct comparison of i.v. zoledronic acid and i.v. pamidronate confirmed at least equivalent efficacy in a single large study. In three studies (3405 patients with BCBM), compared with bisphosphonates, subcutaneous (s.c.) denosumab was more effective in reducing the risk of SREs (RR 0.78; 95% CI 0.72 to 0.85; P < 0.00001).Bisphosphonates reduced the SRE rate in 12 studies (median reduction 28%, range 14% to 48%), with statistically significant reductions reported in 10 studies. Women with BCBM treated with bisphosphonates showed significant delays in the median time to SREs. Compared with placebo or no bisphosphonates, treatment with bisphosphonates significantly improved bone pain in six out of eleven studies. Improvements in global QoL with bisphosphonates compared to placebo were reported in two out of five studies (both ibandronate studies). Treatment with bisphosphonates did not appear to affect survival in women with BCBM. Compared to i.v. zoledronic acid, denosumab also significantly reduced the SRE rate, delayed the time to SREs and prolonged the time in developing pain for patients with no or mild pain at baseline; but there was no difference in survival between patients treated with denosumab and zoledronic acid.Bisphosphonates in women with ABC without clinically evident bone metastases did not reduce the incidence of bone metastases, or improve survival in three studies (320 patients).In seven studies (7847 patients with EBC), currently there is no evidence supporting bisphosphonates in reducing the incidence of bone metastases compared to no bisphosphonates (RR 0.94; 95% CI 0.82 to 1.07; P = 0.36). In three studies (2190 patients with EBC), early bisphosphonate treatment also did not significantly reduce the incidence of bone metastases compared to delayed bisphosphonate treatment (RR 0.73; 95% CI 0.40 to 1.33; P = 0.31). Currently, there is insufficient evidence to make a conclusion about the role of adjuvant bisphosphonates in reducing visceral metastases, locoregional recurrence and total recurrence, or improving survival. There was strong heterogeneity in EBC studies examining the outcomes of total recurrence and survival.Reported toxicity was generally mild. Renal toxicity and osteonecrosis of the jaw (ONJ) have been identified as potential problems with bisphosphonate use. ONJ was reported at similar rates for patients on denosumab compared to zoledronic acid. This highlighted a need for maintaining good oral care, prior to and during treatment, for patients who received long-term bone agents.

AUTHORS' CONCLUSIONS

In women with clinically evident BCBM, bisphosphonates (oral and i.v.) and denosumab (s.c.) reduced the risk of developing SREs, as well as delaying the time to SREs. Some bisphosphonates may also reduce bone pain and may improve QoL. The optimal timing and duration of treatment for patients with BCBM remains uncertain. There is currently insufficient evidence to support the routine use of bisphosphonates as adjuvant treatment for patients with EBC. However, a number of large clinical trials investigating bisphosphonates in EBC have completed accrual and are awaiting results.

Denosumab and the current status of bone-modifying drugs in breast cancer

BACKGROUND

Bone-modifying therapy is a primary research interest in breast cancer. Several features contribute to the importance of the bone environment in the management of breast cancer. Firstly, bone metastases represent the most common site of breast cancer metastases and secondly, the emergence of cancer treatment-induced bone loss (CTIBL) among breast cancer survivors and patients is of increasing concern. Furthermore, concordant with the "seed and soil" theory, agents that alter the bone microenvironment may even prevent tumor cell seeding in bone and limit cancer growth.

MATERIAL AND METHODS

Medical databases and conference proceedings were searched to identify articles, abstracts and clinical trials that have or are investigating denosumab and bisphosphonates in cancer therapy. Our search included a predefined focus on bone-modifying therapies in early and advanced breast cancer.

RESULTS AND DISCUSSION

Bisphosphonates (BPs) have an established role both in the prevention and treatment of CTIBL and have been studied in the adjuvant setting for early breast cancer (EBC). Denosumab is a monoclonal antibody directed against RANK ligand and thereby inhibits osteoclastogenesis and bone resportion. It is the newest agent approved for the treatment of postmenopausal osteoporosis and the prevention of skeletal-related events (SRE) in cancer patients with solid tumors and bone metastases. Denosumab has a favorable toxicity profile in comparison to BPs and has the potential to improve cancer outcomes.

CONCLUSION

This review examines the existing role of denosumab in the treatment of bone complications of breast cancer and its potential role as adjuvant therapy.

Perspectives in the elderly patient: benefits and limits of bisphosphonates and denosumab

Skeletal metastases affect a large percentage of the cancer population and contribute to a marked decrease in their quality of life and survival, in particular in elderly population. A future end-point of bone-protecting therapy is the demonstration of its ability to prevent or improve results in the treatment of metastatic disease, enlarging their clinical indications in metastatic and osteoporotic setting with different schedules. In this chapter we will discuss on pharmacokinetic and pharmacodynamic interactions of bisphosphonates in elderly, and the preclinical and clinical evidences of anticancer activity of bone-targeted therapies will be critically described. The clinical results of new targeted therapies (such as rank/rankl/OPG inhibition) will be reported both in bone metastatic and in adjuvant settings. Finally, the prevention of cancer treatment-induced bone loss (CTIBL) represents both in young and more in old patients an emerging issue in the bone health care. For this reason, this chapter will discuss the results of current therapies in this clinical setting.

New approaches to treating and preventing bone metastases

PURPOSE OF REVIEW

Treatment and prevention of bone metastases is a major problem in patients with cancer. New treatment of bone metastases are needed to maintain the quality of life of our patients with metastastic bone disease. In addition, promising preliminary results suggest that bone-directed therapies may be able to prevent both skeletal and extraskeletal metastases

RECENT FINDINGS

For the past decade intravenous bisphosphonates have been the mainstay of treatment of patients with bone metastases. New therapies such as the antibody to RANKL (denosumab) are undergoing phase III clinical testing. In addition, confirmatory studies suggesting that bisphosphonates can prevent metastatic disease are underway.

SUMMARY

Understanding the biology of bone metastases has uncovered many new potential therapies for the treatment and prevention of bone metastases. Many of these potential new approaches are discussed in the enclosed article.

Adjuvant endocrine therapy plus zoledronic acid in premenopausal women with early-stage breast cancer: 62-month follow-up from the ABCSG-12 randomised trial

BACKGROUND

Analysis of the Austrian Breast and Colorectal Cancer Study Group trial-12 (ABCSG-12) at 48 months' follow-up showed that addition of zoledronic acid to adjuvant endocrine therapy significantly improved disease-free survival. We have now assessed long-term clinical efficacy including disease-free survival and disease outcomes in patients receiving anastrozole or tamoxifen with or without zoledronic acid.

METHODS

ABSCG-12 is a randomised, controlled, open-label, two-by-two factorial, multicentre trial in 1803 premenopausal women with endocrine-receptor-positive early-stage (stage I-II) breast cancer receiving goserelin (3.6 mg every 28 days), comparing the efficacy and safety of anastrozole (1 mg per day) or tamoxifen (20 mg per day) with or without zoledronic acid (4 mg every 6 months) for 3 years. Randomisation (1:1:1:1 ratio) was computerised and based on the Pocock and Simon minimisation method to balance the four treatment arms across eight prognostic variables (age, neoadjuvant chemotherapy, pathological tumour stage; lymph-node involvement, type of surgery or locoregional therapy, complete axillary dissection, intraoperative radiation therapy, and geographical region). Treatment allocation was not masked. The primary endpoint was disease-free survival (defined as disease recurrence or death) and analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00295646; follow-up is ongoing.

FINDINGS

At a median follow-up of 62 months (range 0-114.4 months), more than 2 years after treatment completion, 186 disease-free survival events had been reported (53 events in 450 patients on tamoxifen alone, 57 in 453 patients on anastrozole alone, 36 in 450 patients on tamoxifen plus zoledronic acid, and 40 in 450 patients on anastrozole plus zoledronic acid). Zoledronic acid reduced risk of disease-free survival events overall (HR 0.68, 95% CI 0.51-0.91; p=0.009), although the difference was not significant in the tamoxifen (HR 0.67, 95% CI 0.44-1.03; p=0.067) and anastrozole arms (HR 0.68, 95% CI 0.45-1.02; p=0.061) assessed separately. Zoledronic acid did not significantly affect risk of death (30 deaths with zoledronic acid vs 43 deaths without; HR 0.67, 95% CI 0.41-1.07; p=0.09). There was no difference in disease-free survival between patients on tamoxifen alone versus anastrozole alone (HR 1.08, 95% CI 0.81-1.44; p=0.591), but overall survival was worse with anastrozole than with tamoxifen (46 vs 27 deaths; HR 1.75, 95% CI 1.08-2.83; p=0.02). Treatments were generally well tolerated, with no reports of renal failure or osteonecrosis of the jaw. Bone pain was reported in 601 patients (33%; 349 patients on zoledronic acid vs 252 not on the drug), fatigue in 361 (20%; 192 vs 169), headache in 280 (16%; 147 vs 133), and arthralgia in 266 (15%; 145 vs 121).

INTERPRETATION

Addition of zoledronic acid improved disease-free survival in the patients taking anastrozole or tamoxifen. There was no difference in disease-free survival between patients receiving anastrozole and tamoxifen overall, but those on anastrozole alone had inferior overall survival. These data show persistent benefits with zoledronic acid and support its addition to adjuvant endocrine therapy in premenopausal patients with early-stage breast cancer.

FUNDING

AstraZeneca; Novartis.

Tumor-Specific Systemic Treatment in Advanced Breast Cancer - How Long does it Make Sense?

SUMMARY: Metastatic breast cancer (MBC) is a chronic and incurable disease which can be kept steady for a long time with continuous oncologic therapy. There are various treatment options. Disease-free as well as overall survival were prolonged in many pharmaceutical studies. The therapist focuses on these oncologic parameters as well as the patient's quality of life. One central point of the communication between doctor and patient is the prediction by the medical team of how long to continue oncologic therapy and when to start palliative medicine in terms of best palliative care. Treatment options currently available for MBC as well as the importance of this difficult communication between the involved parties are pointed out. The end of tumor-specific oncologic therapy does not necessarily mean the end of therapeutic measures for the individual patient.

Optimal management of bone metastases in breast cancer patients

Bone metastasis in breast cancer is a significant clinical problem. It not only indicates incurable disease with a guarded prognosis, but is also associated with skeletal-related morbidities including bone pain, pathological fractures, spinal cord compression, and hypercalcemia. In recent years, the mechanism of bone metastasis has been further elucidated. Bone metastasis involves a vicious cycle of close interaction between the tumor and the bone microenvironment. In patients with bone metastases, the goal of management is to prevent further skeletal-related events, manage complications, reduce bone pain, and improve quality of life. Bisphosphonates are a proven therapy for the above indications. Recently, a drug of a different class, the RANK ligand antibody, denosumab, has been shown to reduce skeletal-related events more than the bisphosphonate, zoledronic acid. Other strategies of clinical value may include surgery, radiotherapy, radiopharmaceuticals, and, of course, effective systemic therapy. In early breast cancer, bisphosphonates may have an antitumor effect and prevent both bone and non-bone metastases. Whilst two important Phase III trials with conflicting results have led to controversy in this topic, final results from these and other key Phase III trials must still be awaited before a firm conclusion can be drawn about the use of bisphosphonates in this setting. Advances in bone markers, predictive biomarkers, multi-imaging modalities, and the introduction of novel agents have ushered in a new era of proactive management for bone metastases in breast cancer.

Bones, breasts, and bisphosphonates: rationale for the use of zoledronic acid in advanced and early breast cancer

Bisphosphonates inhibit osteoclast-mediated bone resorption, thereby inhibiting the release of growth factors necessary to promote cancer cell growth, differentiation, and tumor formation in bone. These agents have demonstrated efficacy for delaying the onset and reducing the incidence of skeletal-related events in the advanced breast cancer setting, and have been shown to prevent cancer therapy-induced bone loss in the early breast cancer setting. Emerging clinical data indicate that the role of bisphosphonates in advanced and early breast cancer is evolving. Retrospective analyses and recent clinical trial data show that zoledronic acid may improve outcomes in some patients with breast cancer. Data from ABCSG-12 and ZO-FAST suggest that zoledronic acid may improve disease-free survival in the adjuvant breast cancer setting in postmenopausal women or women with endocrine therapy-induced menopause, and recent data from a predefined subset of the AZURE trial added to the anticancer story. However, the overall negative AZURE trial also raises questions about the role of bisphosphonates as an anticancer agent in patients with breast cancer. Overall, these data suggest that the addition of zoledronic acid to established anticancer regimens may have potential anticancer benefits in specific patient populations, although more studies are required to define its role.

Zoledronic acid use in cancer patients: more than just supportive care?

Bone is the most common site for metastasis from solid tumors, and the majority of patients will develop bone metastases during the natural course of their disease. Bisphosphonates are an effective treatment for preventing skeletal-related events in patients with bone metastases and may preserve functional independence and quality of life. Although several bisphosphonates have been investigated in patients with solid tumors, only zoledronic acid (ZOL) is approved by the US Food and Drug Administration and the European Medicines Agency for preventing skeletal-related events in patients across a broad range of solid tumors. In addition, bisphosphonates, notably ZOL, prevent cancer treatment-induced bone loss in breast and prostate cancer patients who are receiving endocrine therapy. It also has been demonstrated that ZOL directly and indirectly inhibits cancer cell growth in vitro and growth and tumorigenesis in animal model systems. These properties may produce clinically meaningful benefits. In recent clinical studies in patients with cancer, ZOL improved overall and prolonged disease-free survival. Ongoing clinical trials in patients with solid tumors will provide further insight into the potential of ZOL to prevent distant metastases and improve survival.

Clinical review: Effect of endocrine therapies on bone in breast cancer patients

CONTEXT

Two common strategies are used to treat estrogen receptor-positive breast cancer in women: tamoxifen to inhibit estrogen action, and aromatase inhibitors (AIs) to block estrogen biosynthesis. Recent data suggest that AIs are more effective than tamoxifen in the adjuvant and advanced disease settings and are now being more commonly used. Tamoxifen, as a selective estrogen receptor modulator, exerts estrogenic effects to preserve bone, whereas the AIs profoundly lower estrogen levels and cause bone loss. Recent comparative studies of these agents provide extensive data on fracture rates, bone mineral density, and markers of bone formation and resorption.

OBJECTIVE

The aim of the study was to review the mechanistic effects of estrogen on bone and clinical data regarding bone density, bone turnover markers, and fracture rates in women with breast cancer taking tamoxifen or AIs.

EVIDENCE ACQUISITION AND SYNTHESIS

Data presented reflect a review of the literature and data integration from the perspective of the author's knowledge of the field.

RESULTS

Tamoxifen increases bone density and reduces fractures in postmenopausal women with breast cancer, whereas AIs increase rate of fracture, accelerate loss of bone mineral density, and enhance levels of markers of bone formation and resorption. Bisphosphonates and denosumab counteract the effects of the AIs on bone. Guidelines for management of AI-induced bone loss are available from several sources, but a simple algorithm guides decision making most effectively.

CONCLUSIONS

Endocrine therapy for postmenopausal women with breast cancer exerts substantial effects on bone, and guidelines are available to assist in the management of bone-related problems.

Improving progression-free and overall survival in patients with cancer: a potential role for bisphosphonates

INTRODUCTION

Bisphosphonates are a well-established therapy for patients with multiple myeloma or bone metastases from advanced cancers and are used routinely to delay the onset and reduce the risk of skeletal-related events. Emerging evidence indicates that they also may provide additional anticancer benefits. These developments warrant reappraisal of their role in patients with cancer and reevaluation of optimal therapeutic regimens.

AREAS COVERED

This article reviews the evidence of the anticancer activity of bisphosphonates in patients with solid tumors or multiple myeloma. The underlying mechanisms of the anticancer activity of bisphosphonates are elucidated from preclinical and translational data that show that bisphosphonates suppress tumor growth and survival, inhibit tumor-mediated angiogenesis, or stimulate host anticancer immune response. These data also provide insights into the potential for therapeutic combinations. Preclinical and clinical data relating to the anticancer effects of bisphosphonates are reviewed by cancer type.

EXPERT OPINION

Future trials of bisphosphonates in cancer patients will explore the underlying mechanism of the anticancer benefit in greater detail and attempt to examine critically the potential clinical benefit in individual cancer types in early/advanced disease.

Prevention of bone metastases and management of bone health in early breast cancer

Treatment options for women with early-stage breast cancer have never been better, and the addition of bisphosphonates to adjuvant therapy is a valuable new tool capable of substantially improving clinical outcomes for these women. Several recent studies demonstrated that the anticancer activity of bisphosphonates is not limited to bone, and can translate into a reduction in disease recurrence, including reductions in locoregional and distant metastases. In addition, bisphosphonates maintain bone health during adjuvant therapy; this may be especially important for women who are at high risk for fracture.

Antitumor effects and anticancer applications of bisphosphonates

Bisphosphonates are firmly entrenched in the treatment of metastatic bone disease secondary to several tumor types, including breast cancer, prostate cancer, and myeloma. More recently, an emerging body of preclinical and clinical evidence indicates that bisphosphonates might also exhibit antitumor activity. This expanded role for bisphosphonates in the adjuvant setting might have profound clinical implications in many cancer types, particularly in the context of prevention of bone metastasis. Increased understanding of the mechanistic basis of the antitumor effects indicates that these might occur via direct mechanisms such as induction of apoptosis and inhibition of tumor cell adhesion and invasion, as well as indirect mechanisms such as inhibition of angiogenesis. There is also considerable evidence to suggest that nitrogen-containing bisphosphonates might exert additive or synergistic interactions with standard cytotoxic agents. However, mature clinical data with bisphosphonates are limited and, thus far, provide conflicting evidence regarding the antitumor role of bisphosphonates, but have mostly been conducted with first-generation bisphosphonates such as clodronate that are not as effective as next-generation bisphosphonates. Several large randomized clinical trials are ongoing with the next-generation bisphosphonate zoledronic acid to prospectively confirm an antitumor role for bisphosphonates in various tumor types. This review assesses the current body of preclinical and clinical evidence in favor of an antitumor effect of bisphosphonates in different cancer types.

Outcome of patients with early breast cancer receiving nitrogen-containing bisphosphonates: a comparative analysis from the Metropolitan Detroit Cancer Surveillance System

BACKGROUND

Preclinical data suggest that bisphosphonates exhibit antitumor activity. However, clinical studies indicated conflicting results. In this study, we compared the overall survival (OS) of postmenopausal patients with nonmetastatic invasive breast cancer who received any of the second-generation nitrogen-containing bisphosphonates for osteopenia or osteoporosis, with the survival of those who did not.

PATIENTS AND METHODS

We conducted a retrospective study at the Wayne State University/Karmanos Cancer institute (KCI) in Detroit, Michigan and extracted data from the Metropolitan Detroit Cancer Surveillance System (MDCSS), a Surveillance, Epidemiology and End Results (SEER) registry. Patients > 50 years of age with stage I, II, or III invasive breast cancer between the years 2000 through 2003 were included. Information regarding medications was extracted from the patients' medical records.

RESULTS

A total of 696 women with stage I-III breast cancer were included. Ninety-seven women (14%) used nitrogen-containing bisphosphonates. The difference in OS between bisphosphonate users and nonusers was not statistically significant (P = .32) at 3 years. After adjusting for differences between the groups in age, stage of disease, hormone receptor status, endocrine therapy, vitamin D, and calcium use, there was a marginally significant (P = .07) difference in survival; bisphosphonate users had poorer survival than nonusers.

CONCLUSION

Our results indicate that the use of nitrogen-containing bisphosphonates is not associated with improved OS in patients with nonmetastatic breast cancer, even after adjusting for known prognostic factors, but with a marginally worse OS. Further research is awaited to clarify the role of bisphosphonates in the adjuvant setting.

Understanding and optimizing bone health in breast cancer

Bone is the preferred site of metastasis for breast cancer, and presence of skeletal lesions is associated with significant morbidity and poor prognosis. Skeletal-related effects such as pain, pathologic fractures, spinal compression, and hypercalcemia are frequent consequences of skeletal lesions of breast cancer that have debilitating effects on the patients' quality of life. In addition to direct cancer effects on the skeleton, therapies commonly used to treat patients with breast cancer such as chemotherapy and aromatase inhibitors (AI) result in cancer therapy-induced bone loss (CTIBL) which is associated with increased risk of skeletal complications such as fractures. Bisphosphonates are a class of antiresorptive drugs that are now firmly established as the cornerstone of the management of skeletal-related events due to breast cancer. Other novel bone-targeting agents such as the anti-receptor activator of NF-κB ligand (RANKL) monoclonal antibody denosumab are also showing promising activity in the treatment of bone metastasis secondary to breast cancer. Moreover, recent provocative evidence suggests that bisphosphonates might also exhibit antitumor activity via direct and indirect mechanisms. The goal of this review is to summarize the pathophysiology of osteolytic bone lesions secondary to breast cancer, provide clinical evidence of currently available bone-targeted drugs in the treatment of bone metastasis and CTIBL, and explore the antitumor activity of current bone-targeted agents in patients with breast cancer.

Metastasis and bone loss: advancing treatment and prevention

Tumor metastasis to the skeleton affects over 400,000 individuals in the United States annually, more than any other site of metastasis, including significant proportions of patients with breast, prostate, lung and other solid tumors. Research on the bone microenvironment and its role in metastasis suggests a complex role in tumor growth. Parallel preclinical and clinical investigations into the role of adjuvant bone-targeted agents in preventing metastasis and avoiding cancer therapy-induced bone loss have recently reported exciting and intriguing results. A multidisciplinary consensus conference convened to review recent progress in basic and clinical research, assess gaps in current knowledge and prioritize recommendations to advance research over the next 5 years. The program addressed three topics: advancing understanding of metastasis prevention in the context of bone pathophysiology; developing therapeutic approaches to prevent metastasis and defining strategies to prevent cancer therapy-induced bone loss. Several priorities were identified: (1) further investigate the effects of bone-targeted therapies on tumor and immune cell interactions within the bone microenvironment; (2) utilize and further develop preclinical models to study combination therapies; (3) conduct clinical studies of bone-targeted therapies with radiation and chemotherapy across a range of solid tumors; (4) develop biomarkers to identify patients most likely to benefit from bone-targeted therapies; (5) educate physicians on bone loss and fracture risk; (6) define optimal endpoints and new measures of efficacy for future clinical trials; and (7) define the optimum type, dose and schedule of adjuvant bone-targeted therapy.

Optimizing clinical benefits of bisphosphonates in cancer patients with bone metastases

Malignant bone disease is common in patients with advanced solid tumors or multiple myeloma. Bisphosphonates have been found to be important treatments for bone metastases. A positive benefit-risk ratio for bisphosphonates has been established, and ongoing clinical trials will determine whether individualized therapy is possible.

Bisphosphonates are important treatments for bone metastases. Considerations for optimizing the clinical benefits of bisphosphonates include efficacy, compliance, and safety. Several bisphosphonates are approved for clinical use; however, few have demonstrated broad efficacy in the oncology setting and been compared directly in clinical trials. Among patients with bone metastases from breast cancer, the efficacy of approved bisphosphonates was evaluated in a Cochrane review, showing a reduction in the risk of skeletal-related events (SREs) ranging from 8% to 41% compared with placebo. Between-trial comparisons are confounded by inconsistencies in trial design, SRE definition, and endpoint selection. Zoledronic acid has demonstrated clinical benefits beyond those of pamidronate in a head-to-head trial that included patients with breast cancer or multiple myeloma. Compliance and adherence also have effects on treatment efficacy. In a comparison study, the adherence rates with oral bisphosphonates were found to be significantly lower compared with those of intravenous bisphosphonates. The safety profiles of oral and intravenous bisphosphonates differ. Oral bisphosphonates are associated with gastrointestinal side effects, whereas intravenous bisphosphonates have dose- and infusion rate–dependent effects on renal function. Osteonecrosis of the jaw is an uncommon but serious event in patients receiving monthly intravenous bisphosphonates or denosumab. The incidence of this event can be reduced with careful oral hygiene. A positive benefit-risk ratio for bisphosphonates has been established, and ongoing clinical trials will determine whether individualized therapy is possible.

Adjuvant Bisphosphonate Therapy in Postmenopausal Breast Cancer Patients

Adjuvant bisphosphonate therapy is increasingly used in postmenopausal breast cancer patients. This is based on level-one evidence that bisphosphonates, particularly zoledronic acid, can effectively prevent cancer treatment-induced bone loss in breast cancer patients receiving estradiol-lowering endocrine therapies such as aromatase inhibitors. Furthermore, emerging data from large clinical trials suggest that additional anticancer benefits can be derived due to a positive impact on the bone marrow microenvironment.

Breast cancer in young women

Although uncommon, breast cancer in young women is worthy of special attention due to the unique and complex issues that are raised. This article reviews specific challenges associated with the care of younger breast cancer patients, which include fertility preservation, management of inherited breast cancer syndromes, maintenance of bone health, secondary prevention, and attention to psychosocial issues.

[Bisphosphonates in adjuvant therapy of breast cancer]

For more than 10 years, based on the results with the bisphosphonate clodronic acid, it has been discussed, whether the occurrence of breast cancer metastases can be avoided or at least delayed by administration of bisphosphonates. The published results of recent studies applying, e.g., the bisphosphonates zoledronic and ibandronic acid, respectively, seem promising at first glance, especially, if the therapeutic acceptance of bisphosphonates in the indications osteoporosis and bone-related complications of malignancies, respectively, as well as their spectrum of side effects are taken into account and their putative mechanism of action is considered. There is a broad consensus that the existing data basis suffices to demonstrate importance of bisphosphonates in an adjuvant therapeutic setting of breast cancer. Significant relative risk reductions of, e.g., 36% in disease-free survival are very impressing and the corresponding absolute values of 3.2% are second-line communications. However, evaluation of all studies published so far according to the criteria of evidence-based medicine demonstrates many open questions and several methodical insufficiencies. Therefore, effectiveness and benefit of an adjuvant therapeutic application of bisphosphonates in breast cancer patients cannot be drawn out of evidence-based data. A recommendation of this therapy is given only by the German Working Pool of Gynecologic Oncology (AGO), but limited to study participation.