The benefits of timely intervention with zoledronic acid in patients with metastatic prostate cancer to bones: a retrospective study of the US Veterans Affairs population

Risk of skeletal related events among elderly prostate cancer patients by site of metastasis at diagnosis

The purpose of this study was to estimate the risk of developing skeletal-related events (SREs) based on site of metastasis at diagnosis and identify other predictors of developing SREs among metastatic prostate cancer patients. We conducted a retrospective cohort study using linked SEER (Surveillance, Epidemiology, and End Results) and Medicare data and identified men over the age of 65 with incident metastatic prostate cancer diagnosed during 2005-2009. SREs included radiation (RAD), pathological fractures (PF), bone surgery (BS), and spinal cord compression (SCC). The association between site of metastasis at diagnosis and SRE was examined using a Cox proportional hazards model that accounts for death as a competing risk. Among 4404 men (median age: 79 years) with incident metastatic prostate cancer, 44% experienced SREs at a median of 9.6 months post diagnosis. Compared to bone metastasis only, our model showed that patients were significantly less likely to develop SREs if they had LN-only metastasis at diagnosis (Sub-Hazard Ratio [SHR] 0.56; 95% Confidence Interval [CI]: 0.43-0.72) or unknown site of metastasis (SHR: 0.79; CI: 0.64-0.97). Other predictors of reduced SRE risk were age 80+ years (SHR: 0.83; CI: 0.75-0.91), non-Hispanic Black (SHR: 0.77; CI: 0.65-0.90), or being diagnosed in year 2009 (SHR: 0.85; CI: 0.72-0.99). Patients were significantly more likely to develop SREs if they received androgen deprivation therapy (SHR: 1.73; CI: 1.48-2.02) or had Gleason score 8-10 disease (SHR: 0.79; CI: 0.64-0.97). Compared to patients who present with bone metastasis only at diagnosis, patients presenting with other metastatic sites have similar risk of developing SREs, with the exception of those presenting with lymph node only metastasis who have a significantly reduced risk of SREs.

Statins Are Associated With Reduced Mortality in Multiple Myeloma

Purpose The 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) have activity in one of the pathways influenced by nitrogen-containing bisphosphonates, which are associated with improved survival in multiple myeloma (MM). To understand the benefit of statins in MM, we evaluated the association between statin use and mortality in a large cohort of patients with MM. Patients and Methods From the Veterans Administration Central Cancer Registry, we identified patients diagnosed with MM between 1999 and 2013. We defined statin use as the presence of any prescription for a statin within 3 months before or any time after MM diagnosis. Cox proportional hazards regression assessed the association of statin use with mortality, while controlling for known MM prognostic factors. Results We identified a cohort of 4,957 patients, of whom 2,294 received statin therapy. Statin use was associated with a 21% decrease in all-cause mortality (adjusted hazard ratio, 0.79; 95% CI, 0.73 to 0.86; P < .001) as well as a 24% decrease in MM-specific mortality (adjusted hazard ratio, 0.76; 95% CI, 0.67 to 0.86; P < .001). This association remained significant across all sensitivity analyses. In addition to reductions in mortality, statin use was associated with a 31% decreased risk of developing a skeletal-related event. Conclusion In this cohort study of US veterans with MM, statin therapy was associated with a reduced risk of both all-cause and MM-specific mortality. Our findings suggest a potential role for statin therapy in patients with MM. The putative benefit of statin therapy in MM should be corroborated in prospective studies.

Measurement of skeletal related events in SEER-Medicare: a comparison of claims-based methods

Background

Skeletal related events (SREs) are common in men with metastatic prostate cancer (mPC). Various methods have been used to identify SREs from claims data. The objective of this study was to provide a framework for measuring SREs from claims and compare SRE prevalence and cumulative incidence estimates based on alternative approaches in men with mPC.

Methods

Several claims-based approaches for identifying SREs were developed and applied to data for men aged [greater than or equal to] 66 years newly diagnosed with mPC between 2000 and 2009 in the SEER-Medicare datasets and followed through 2010 or until censoring. Post-diagnosis SREs were identified using claims that indicated spinal cord compression (SCC), pathologic fracture (PF), surgery to bone (BS), or radiation (suggestive of bone palliative radiation, RAD). To measure SRE prevalence, two SRE definitions were created: ‘base case’ (most commonly used in the literature) and ‘alternative’ in which different claims were used to identify each type of SRE. To measure cumulative incidence, we used the ‘base case’ definition and applied three periods in which claims were clustered to episodes: 14-, 21-, and 28-day windows.

Results

Among 8997 mPC patients, 46 % experienced an SRE according to the ‘base case’ definition and 43 % patients experienced an SRE according to the ‘alternative’ definition. Varying the code definition from ‘base case’ to ‘alternative’ resulted in an 8 % increase in the overall SRE prevalence. Using the 21-day window, a total of 12,930 SRE episodes were observed during follow up. Varying the window length from 21 to 28 days resulted in an 8 % decrease in SRE cumulative incidence (RAD: 10 %, PF: 8 %, SCC: 6 %, BS: 0.2 %).

Conclusions

SRE prevalence was affected by the codes used, with PF being most impacted. The overall SRE cumulative incidence was affected by the window length used, with RAD being most affected. These results underscore the importance of the baseline definitions used to study claims data when attempting to understand relevant clinical events such as SREs in the real world setting.

Clinical and economic burden of bone metastasis and skeletal-related events in prostate cancer

PURPOSE OF REVIEW

We review the clinical trials and observational studies literature regarding the clinical and economic burden of bone metastasis and skeletal-related events (SREs) in prostate cancer, and discuss current gaps in understanding the impact of bone metastasis in this disease.

RECENT FINDINGS

Trial data indicate that SREs occur in half of prostate cancer patients with bone metastasis in the absence of treatment, and 30-45% among those who receive bone-modifying agents. In the United States, the cost of SRE ranged from $7553 per radiation episode to $88 838 per bone surgery episode. Prevalence of SRE, time to SRE occurrence, and cost of SRE varied across studies because of differences in study populations, follow-up period, and the algorithm used to measure SRE. There is limited evidence on the clinical and economic impact by SRE subtype. Information regarding patient-reported outcomes and costs from the patient's perspective is lacking.

SUMMARY

Bone metastasis and SREs in prostate cancer patients are associated with considerable morbidity, reduced survival, and substantial economic burden. Consistent study methodology, particularly the measurement of SREs, is necessary to allow comparison of estimates across studies. The inclusion of patient-centered clinical and economic outcomes in future research will provide pertinent information regarding the burden of bone metastasis and SREs.

Comparative effectiveness on survival of zoledronic acid versus pamidronate in multiple myeloma

Zoledronic acid and pamidronate are the two bisphosphonates approved in the United States to reduce multiple myeloma skeletal complications. Little prior evidence exists comparing survival outcomes between the two. We evaluated the incidence of skeletal-related events and overall survival in patients with myeloma treated with zoledronic acid versus pamidronate using a cohort of 1018 United States veterans. At a median follow-up of 26.9 months, patients receiving zoledronic acid had a 22% reduction in risk of death compared to pamidronate (hazard ratio 0.78; 95% confidence interval, 0.67-0.92). The benefit persisted after controlling for potential confounders. Adjusted Cox modeling with inverse probability weighting and propensity score matching supported these findings. Zoledronic acid was also associated with a 25% decrease in skeletal-related events. Zoledronic acid is associated with increased overall survival and decreased skeletal-related events compared to pamidronate in patients with multiple myeloma and should become the preferred bisphosphonate.

Use of intravenous bisphosphonates in patients with breast, lung, or prostate cancer and metastases to bone: a 15-year study in two large US health systems

PURPOSE

The purpose of this paper is to document the use of intravenous (IV) bisphosphonates for prevention of skeletal-related events (SREs) in patients with bone metastases (BM) due to breast cancer (BC), lung cancer (LC), or prostate cancer (PC).

METHODS

Using data from two large US health systems, we identified all patients aged ≥ 18 years with primary BC, LC, or PC and newly diagnosed BM between 1/1/1995 and 12/31/2009. Starting with the diagnosis of BM, we reviewed medical and administrative records for evidence of receipt of IV bisphosphonates (zoledronic acid or pamidronate) and occurrence of SREs. Initiation of IV bisphosphonates prior to occurrence of an SRE was designated "primary prophylaxis"; use following an SRE was designated "secondary prophylaxis".

RESULTS

We identified a total of 1,193 patients with newly diagnosed BM, including 400 with BC, 332 with LC, and 461 with PC. Use of IV bisphosphonates was substantially higher in BC (55.8 % of all patients) than in LC (14.8 %) or PC (20.2 %). Use of IV bisphosphonates was fairly evenly split between primary and secondary prophylaxis in BC (26.3 vs. 29.5 %, respectively) and PC (10.6 vs 9.5 %); in LC, however, primary prophylaxis was much less common than secondary prophylaxis (4.8 vs 9.9 %).

CONCLUSIONS

Almost one half of all patients with BM due to BC, and substantially more with LC and PC, do not receive IV bisphosphonates. Among patients receiving such therapy, treatment often is not initiated until after the occurrence of an SRE. Our study suggests that IV bisphosphonates may be substantially underutilized in patients with BM due to these common cancers.

[Bone metastasis in prostate cancer]

Bone metastasis and skeletal complications have a devastating impact on the quality of life and are a major cause of morbidity in prostate cancer patients. In addition to established bone-targeted therapies, new drugs such as endothelin A receptor antagonists, MET and VEGFR-2 antagonists or radiopharmaceuticals are in the focus of development. The standard care in prostate cancer patients with bone metastases to prevent skeletal-related events (SRE) are bisphosphonates. Denosumab, a human monoclonal antibody against RANKL, appeared to be superior to zoledronic acid for prevention of SRE and has been shown to prolong bone metastases-free survival. In contrast to zoledronic acid, denosumab clearance is not dependent on kidney function and can be administered subcutaneously. Similar rates of toxicity were observed for both substances; however, long-term data for denosumab are limited.