The skeleton is the most common organ to be affected by metastatic cancer and the site of disease that produces the greatest morbidity. Skeletal morbidity includes pain that requires radiotherapy, hypercalcemia, pathologic fracture, and spinal cord or nerve root compression. From randomized trials in advanced cancer, it can be seen that one of these major skeletal events occurs on average every 3 to 6 months. Additionally, metastatic disease may remain confined to the skeleton with the decline in quality of life and eventual death almost entirely due to skeletal complications and their treatment. The prognosis of metastatic bone disease is dependent on the primary site, with breast and prostate cancers associated with a survival measured in years compared with lung cancer, where the average survival is only a matter of months. Additionally, the presence of extraosseous disease and the extent and tempo of the bone disease are powerful predictors of outcome. The latter is best estimated by measurement of bone-specific markers, and recent studies have shown a strong correlation between the rate of bone resorption and clinical outcome, both in terms of skeletal morbidity and progression of the underlying disease or death. Our improved understanding of prognostic and predictive factors may enable delivery of a more personalized treatment for the individual patient and a more cost-effective use of health care resources.

Purpose: Three large, randomized trials of patients with bone metastases recently demonstrated that zoledronic acid reduces the risk of skeletal-related events. These trials provide an opportunity for investigating the correlation between bone metabolism and clinical outcome during bisphosphonate therapy. Patients and Methods: Urinary measurements of N-telopeptide (Ntx) and serum bone alkaline phosphatase (BAP) were obtained in 1,824 bisphosphonate-treated patients—1,462 with zoledronic acid (breast, 490; prostate, 411; myeloma, 210; non–small-cell lung, 183; other, 168) and 362 with pamidronate (breast, 254; myeloma, 108). This exploratory cohort analysis grouped patients by baseline and most recent levels of Ntx as low (< 50 nmol/mmol creatinine), moderate (50 to 99 nmol/mmol creatinine), or high (≥ 100 nmol/mmol creatinine), and BAP as low (< 146 U/L) or high (≥ 146 U/L). The relative risks for negative clinical outcomes were estimated for each group using multiple-event and Cox regression models with time-varying covariates. Results: Patients with high and moderate Ntx levels had 2-fold increases in their risk of skeletal complications and disease progression compared with patients with low Ntx levels (P < .001 for all). High Ntx levels in each solid tumor category were associated with a 4- to 6-fold increased risk of death on study, and moderate Ntx levels a 2- to 4-fold increased risk compared with low Ntx levels (P < .001 for all). Bone alkaline phosphatase also showed some correlation with risk of negative clinical outcomes. Conclusion: The bone resorption marker Ntx provides valuable prognostic information in patients with bone metastases receiving bisphosphonates.

Data suggest that the adjuvant use of bisphosphonates reduces rates of recurrence and death in patients with early-stage breast cancer. We conducted a study to determine whether treatment with zoledronic acid, in addition to standard adjuvant therapy, would improve disease outcomes in such patients. In this open-label phase 3 study, we randomly assigned 3360 patients to receive standard adjuvant systemic therapy either with or without zoledronic acid. The zoledronic acid was administered every 3 to 4 weeks for 6 doses and then every 3 to 6 months to complete 5 years of treatment. The primary end point of the study was disease-free survival. A second interim analysis revealed that a prespecified boundary for lack of benefit had been crossed. At a median follow-up of 59 months, there was no significant between-group difference in the primary end point, with a rate of disease-free survival of 77% in each group (adjusted hazard ratio in the zoledronic acid group, 0.98; 95% confidence interval [CI], 0.85 to 1.13; P=0.79). Disease recurrence or death occurred in 377 patients in the zoledronic acid group and 375 of those in the control group. The numbers of deaths — 243 in the zoledronic acid group and 276 in the control group — were also similar, resulting in rates of overall survival of 85.4% in the zoledronic acid group and 83.1% in the control group (adjusted hazard ratio, 0.85; 95% CI, 0.72 to 1.01; P=0.07). In the zoledronic acid group, there were 17 confirmed cases of osteonecrosis of the jaw (cumulative incidence, 1.1%; 95% CI, 0.6 to 1.7; P<0.001) and 9 suspected cases; there were no cases in the control group. Rates of other adverse effects were similar in the two study groups. These findings do not support the routine use of zoledronic acid in the adjuvant management of breast cancer. (Funded by Novartis Pharmaceuticals and the National Cancer Research Network; AZURE Current Controlled Trials number, ISRCTN79831382.)

Aromatase inhibitors are the preferred adjuvant endocrine therapy for the majority of postmenopausal women with hormone-responsive early breast cancer. Although generally more effective than tamoxifen, aromatase inhibitor therapy is associated with increased bone loss and fracture risk. Postmenopausal women receiving adjuvant letrozole (2.5 mg/day for 5 years; N = 1065) were randomly assigned to immediate zoledronic acid (zoledronate) 4 mg every 6 months for 5 years, or delayed zoledronate (initiated for fracture or on-study bone mineral density [BMD] decrease). The primary end point was the change in lumbar spine BMD at 12 months. Lumbar spine and total hip BMD at subsequent follow-up, disease-free survival (DFS), and overall survival were assessed as secondary end points. At 60 months (final analysis), the mean change in lumbar spine BMD was +4.3% with immediate zoledronate and −5.4% with delayed intervention (P < 0.0001). Immediate zoledronate reduced the risk of DFS events by 34% (hazard ratio [HR] = 0.66; P = 0.0375) with fewer local (0.9% versus 2.3%) and distant (5.5% versus 7.7%) recurrences versus delayed zoledronate. In the delayed group, delayed initiation of zoledronate substantially improved DFS versus no zoledronate (HR = 0.46; P = 0.0334). Immediate zoledronate in postmenopausal women receiving letrozole preserved BMD and is associated with improved DFS compared with letrozole alone. NCT00171340.