Effect of long-term bisphosphonate treatment on morbidity due to bone metastases in breast cancer patients

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 other key bone metabolism pathways. We have studied these agents in both early breast cancer and advanced breast cancer settings. This is an update of the review originally published in 2002 and subsequently updated in 2005 and 2012.

OBJECTIVES

To assess the effects of bisphosphonates and other bone agents in addition to anti-cancer treatment: (i) in women with early breast cancer (EBC); (ii) in women with advanced breast cancer without bone metastases (ABC); and (iii) in women with metastatic breast cancer and bone metastases (BCBM).

SEARCH METHODS

In this review update, we searched Cochrane Breast Cancer's Specialised Register, CENTRAL, MEDLINE, Embase, the World Health Organization's International Clinical Trials Registry Platform (WHO ICTRP) and ClinicalTrials.gov on 19 September 2016.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing: (a) one treatment with a bisphosphonate/bone-acting agent with the same treatment without a bisphosphonate/bone-acting agent; (b) treatment with one bisphosphonate versus treatment with a different bisphosphonate; (c) treatment with a bisphosphonate versus another bone-acting agent of a different mechanism of action (e.g. denosumab); and (d) immediate treatment with a bisphosphonate/bone-acting agent versus delayed treatment of the same bisphosphonate/bone-acting agent.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data, and assessed risk of bias and quality of the evidence. The primary outcome measure was bone metastases for EBC and ABC, and a skeletal-related event (SRE) for BCBM. We derived risk ratios (RRs) for dichotomous outcomes and the meta-analyses used random-effects models. Secondary outcomes included overall survival and disease-free survival for EBC; we derived hazard ratios (HRs) for these time-to-event outcomes where possible. We collected toxicity and quality-of-life information. GRADE was used to assess the quality of evidence for the most important outcomes in each treatment setting.

MAIN RESULTS

We included 44 RCTs involving 37,302 women.In women with EBC, bisphosphonates were associated with a reduced risk of bone metastases compared to placebo/no bisphosphonate (RR 0.86, 95% confidence interval (CI) 0.75 to 0.99; P = 0.03, 11 studies; 15,005 women; moderate-quality evidence with no significant heterogeneity). Bisphosphonates provided an overall survival benefit with time-to-event data (HR 0.91, 95% CI 0.83 to 0.99; P = 0.04; 9 studies; 13,949 women; high-quality evidence with evidence of heterogeneity). Subgroup analysis by menopausal status showed a survival benefit from bisphosphonates in postmenopausal women (HR 0.77, 95% CI 0.66 to 0.90; P = 0.001; 4 studies; 6048 women; high-quality evidence with no evidence of heterogeneity) but no survival benefit for premenopausal women (HR 1.03, 95% CI 0.86 to 1.22; P = 0.78; 2 studies; 3501 women; high-quality evidence with no heterogeneity). There was evidence of no effect of bisphosphonates on disease-free survival (HR 0.94, 95% 0.87 to 1.02; P = 0.13; 7 studies; 12,578 women; high-quality evidence with significant heterogeneity present) however subgroup analyses showed a disease-free survival benefit from bisphosphonates in postmenopausal women only (HR 0.82, 95% CI 0.74 to 0.91; P < 0.001; 7 studies; 8314 women; high-quality evidence with no heterogeneity). Bisphosphonates did not significantly reduce the incidence of fractures when compared to placebo/no bisphosphonates (RR 0.77, 95% CI 0.54 to 1.08, P = 0.13, 6 studies, 7602 women; moderate-quality evidence due to wide confidence intervals). We await mature overall survival and disease-free survival results for denosumab trials.In women with ABC without clinically evident bone metastases, there was no evidence of an effect of bisphosphonates on bone metastases (RR 0.96, 95% CI 0.65 to 1.43; P = 0.86; 3 studies; 330 women; moderate-quality evidence with no heterogeneity) or overall survival (RR 0.89, 95% CI 0.73 to 1.09; P = 0.28; 3 studies; 330 women; high-quality evidence with no heterogeneity) compared to placebo/no bisphosphonates however the confidence intervals were wide. One study reported a trend towards an extended period of time without a SRE with bisphosphonate compared to placebo (low-quality evidence). One study reported quality of life and there was no apparent difference in scores between bisphosphonate and placebo (moderate-quality evidence).In women with BCBM, bisphosphonates reduced the SRE risk by 14% (RR 0.86, 95% CI 0.78 to 0.95; P = 0.003; 9 studies; 2810 women; high-quality evidence with evidence of heterogeneity) compared with placebo/no bisphosphonates. This benefit persisted when administering either intravenous or oral bisphosphonates versus placebo. Bisphosphonates delayed the median time to a SRE with a median ratio of 1.43 (95% CI 1.29 to 1.58; P < 0.00001; 9 studies; 2891 women; high-quality evidence with no heterogeneity) and reduced bone pain (in 6 out of 11 studies; moderate-quality evidence) compared to placebo/no bisphosphonate. Treatment with bisphosphonates did not appear to affect overall survival (RR 1.01, 95% CI 0.91 to 1.11; P = 0.85; 7 studies; 1935 women; moderate-quality evidence with significant heterogeneity). Quality-of-life scores were slightly better with bisphosphonates than placebo at comparable time points (in three out of five studies; moderate-quality evidence) however scores decreased during the course of the studies. Denosumab reduced the risk of developing a SRE compared with bisphosphonates by 22% (RR 0.78, 0.72 to 0.85; P < 0.001; 3 studies, 2345 women). One study reported data on overall survival and observed no difference in survival between denosumab and bisphosphonate.Reported toxicities across all settings were generally mild. Osteonecrosis of the jaw was rare, occurring less than 0.5% in the adjuvant setting (high-quality evidence).

AUTHORS' CONCLUSIONS

For women with EBC, bisphosphonates reduce the risk of bone metastases and provide an overall survival benefit compared to placebo or no bisphosphonates. There is preliminary evidence suggestive that bisphosphonates provide an overall survival and disease-free survival benefit in postmenopausal women only when compared to placebo or no bisphosphonate. This was not a planned subgroup for these early trials, and we await the completion of new large clinical trials assessing benefit for postmenopausal women. For women with BCBM, bisphosphonates reduce the risk of developing SREs, delay the median time to an SRE, and appear to reduce bone pain compared to placebo or no bisphosphonate.

Demographic and clinico-pathological characteristics of breast cancer patients with history of oral alendronate use

Bisphosphonates are the most commonly used agents in the treatment of osteoporosis, and bisphosphonate therapy reduces the risk of skeletally related complications in patients with bone metastases due to malignancy. However, the effect of oral alendronate treatment on clinical and pathological properties of breast cancer has not been reported. Thus, we aimed to investigate retrospectively the demographic and clinico-pathological characteristics of new diagnosis of breast cancer patients with oral alendronate users for longer than 1 year, compared with non-users. Newly diagnosed breast cancer patients from 1998 to 2010 in our clinic were retrospectively analyzed. Patient's demographics, including survival data and tumor characteristics, were obtained from medical charts. Breast cancer patients who were taking oral alendronate more than 12 months at the time of breast cancer diagnosis were enrolled as an alendronate users (n=44), where the patients matched with the same age who were not taking oral alendronate were included as a control group (n=444). A total of 488 patients were included in this study. Forty-four patients received an oral alendronate treatment more than 1 year, and 444 patients were considered as non-users. Median age of both alendronate users and non-users was 57 (33-89). Lower incidence of histological grade III, T3-T4 tumor, and node positivity was seen in alendronate users but not statistically significant. A similar trend for lower incidence of triple negative and higher incidence ER (P=0.13), progesterone receptor (P=0.12), and HER2 positivity (P=0.21) was also seen in alendronate users but not statistically significant. Estimated median disease-free survival was 150 months in alendronate users where as 70 months in non-users (P=0.015). Five-year survival rate in alendronate users was 97.4%, whereas in non-users was 89.8% (P=0.13). The use of oral alendronate for longer than 1 year at the time of breast cancer diagnosis was associated with better clinico-pathological properties and significantly improved disease-free survival in breast cancer patients.

Use of bisphosphonates and risk of breast cancer

A decreased risk of breast cancer has been reported among patients given bisphosphonates. The present aims were to study potential associations between different antiosteoporosis drugs, including bisphosphonates, and the risk of breast cancer before and after start of treatment and to appraise possible dose-effect relationships. From national Danish registers, all female users of bisphosphonates aged ≥40 years and other drugs against osteoporosis between 1996 and 2006 were identified (n = 87,104). This cohort was compared with a control group, where each patient was matched on age with three nonexposed women from the general population (n = 261,322). Before start of most drugs against osteoporosis an increased risk of breast cancer was seen compared to controls (e.g., adjusted OR = 1.09, 95% CI 1.04-1.16 for alendronate). This excess risk was higher in younger women (e.g., OR = 4.48, 95% CI 2.98-6.75 for alendronate in women ≤50 years) and disappeared in women older than 70 years (e.g., OR = 0.95, 95% CI 0.88-1.01 for alendronate). In contrast, a decreased risk of breast cancer was seen after start of alendronate (HR = 0.53, 95% CI 0.38-0.73), etidronate (HR = 0.80, 95% CI 0.73-0.89), and raloxifene (HR = 0.53, 95% CI 0.38-0.73). No dose-response relationship was present for alendronate and etidronate, whereas a decreasing risk was seen with increasing daily dose of raloxifene. Bisphosphonate treatment in women was associated with a reduced risk of breast cancer. However, no causal relationship seemed to be present.

Effect of tamoxifen and aromatase inhibitors on the risk of fractures in women with breast cancer

We studied risk of fractures among women who had used tamoxifen or aromatase inhibitors compared to nonusers in a case-control study. There were 64,548 fracture cases and 193,641 age- and gender-matched controls. Adjustment was made for comorbidity, social factors, and use of other drugs. Use of tamoxifen in general was not associated with any significant change in the risk of any fracture, wrist fractures, and spine fractures. A significantly decreasing relative risk of fractures was seen with increasing dose, although the risk never declined statistically significantly below that in nonusers. An increased risk of hip fractures was seen, but the increase was limited to patients who had used low average doses (<20 mg of tamoxifen/day) and were prior users (i.e., had not used tamoxifen within the last year). Aromatase inhibitors were associated with significant increases in overall risk of fractures and risk of hip fractures. Tamoxifen does not seem to be bone-protective in such a degree that the risk of fractures decreases below that of nonusers. Tamoxifen per se does not seem to increase the risk of fractures. Aromatase inhibitors were associated with a significant increase in the risk of fractures. In women at high risk of fractures, supplementary measures, i.e., bisphosphonates, may be considered.

Cost-effectiveness of Oral Clodronate Compared with Oral Ibandronate, Intravenous Zoledronate or Intravenous Pamidronate in Breast Cancer Patients

This study aimed to identify the effects of different bisphosphonates in reducing skeletal-related events, and to determine whether there are any differences in their cost-effectiveness, taking into account their efficacy, safety profile and administration routes. A systematic literature search of databases, such as PubMed and the Cochrane Controlled Trials Register, supplemented by the latest congress abstracts from meetings of the European Hematology Association and the American Society of Clinical Oncology was conducted up to November 2006. Important references in reviews published by peer-reviewed journals were also taken into consideration. Our base-case cost-effectiveness analysis for Germany and the UK showed cost savings for oral clodronate therapy compared with other bisphosphonate therapies. In Germany, costs per patient of treatment with oral clodronate were €1092.38, €2360.40 and €2500.29 less than with oral ibandronate, intravenous pamidronate and intravenous zoledronate, respectively. The UK results were similar, the costs per patient of treatment with oral clodronate being €841.79, €2989.99 and €3669.19 less than with oral ibandronate, intravenous pamidronate and intravenous zoledronate, respectively.

Effect of the bisphosphonate risedronate on bone metastases in a rat mammary adenocarcinoma model system

Risedronate (NE-58095) is a third-generation bisphosphonate with very potent antiresorptive activity but few toxic effects. The purpose of this work was to evaluate the effect of risedronate treatment on bone metastases produced in a rat breast cancer model. Berlin Druckrey IV rats inoculated with ENU1564 mammary adenocarcinoma cells were treated daily with risedronate or a saline placebo. Survival times, dictated by extraskeletal metastases (lung, heart, and brain), were not affected by risedronate treatment. Risedronate-treated animals had skeletal changes associated with decreased remodeling of bones undergoing endochondral ossification, most prominently affecting the appendicular skeleton. Despite the skeletal alterations induced by the treatment, the distribution of bone metastases throughout the surveyed skeletal sites was similar for treated and untreated animals. Bone metastases were enumerated in histologic sections of distal femur, spine, and skull. Tumor size was estimated from area measurements obtained from histologic lesions in distal femoral metaphyses and vertebral bodies. A greater number of treated rats had no bone metastases in any of the examined sections (30 versus 16.1% of untreated rats). Multiple bone metastases were observed less frequently in treated rats (33.3 versus 71% of untreated rats). Treated rats had fewer observed bone metastases in each examined site than untreated rats (p < or = 0.025). Mean tumor areas in femora and vertebrae were smaller in treated rats (p < or = 0.05), due to the less frequent presence of very large lesions. In untreated animals, osteoclasts appeared to be active at the tumor/bone interface and osseous structures were often completely replaced by expanding tumors. In contrast, metastases in treated animals caused less disruption of skeletal histoarchitecture. The apparent lack of osteoclastic activity and retention of bone within lesions suggested a decreased contribution of osteoclasts to the bone resorptive process. An in vivo immunohistochemical cell proliferation assay failed to reveal differences in the percentage of dividing tumor cells in bone metastatic sites in treated versus untreated animals. The results demonstrate significant effects of risedronate treatment on the incidence and size of observed skeletal metastases in this model.