Abstract
Lung cancer is the most common cancer diagnosed, the leading cause of cancer-related deaths, and bone metastases occurs in 20–40% of lung cancer patients. They often present symptomatically with pain or skeletal related events (SREs), which are independently associated with decreased survival. Bone modifying agents (BMAs) such as Denosumab or bisphosphonates are routinely used, however no specific guidelines exist from the National Comprehensive Cancer Center or the European Society of Medical Oncologists. Perhaps preventing the formation of guidelines is the lack of a high-quality quantitative synthesis of randomized controlled trial (RCT) data to determine the optimal treatment for the patient important outcomes of 1) Overall survival (OS), 2) Time to SRE, 3) SRE incidence, and 4) Pain Resolution. The objective of this study was to perform the first systematic review and network meta-analysis (NMA) to assess the best BMA for treatment of metastatic lung cancer to bone.
We conducted our study in accordance to the PRISMA protocol. We performed a librarian assisted search of MEDLINE, PubMed, EMBASE, and Cochrane Library and Chinese databases including CNKI and Wanfang Data. We included studies that are RCTs reporting outcomes specifically for lung cancer patients treated with a bisphosphonate or Denosumab. Screening, data extraction, risk of bias and GRADE were performed in duplicate. The NMA was performed using a Bayesian probability model with R. Results are reported as relative risks, odds ratios or mean differences, and the I2 value is reported for heterogeneity. We assessed all included articles for risk of bias and applied the novel GRADE framework for NMAs to rate the quality of evidence supporting each outcome.
We included 132 RCTs comprising 11,161 patients with skeletal metastases from lung cancer. For OS, denosumab was ranked above zoledronic acid (ZA) and estimated to confer an average of 3.7 months (95%CI: −0.5 – 7.6) increased survival compared to untreated patients. For time to SRE, denosumab was ranked first with an average of 9.1 additional SRE-free months (95%CI: 4.0 – 14.0) compared to untreated patients, while ZA conferred an additional 4.8 SRE-free months (2.4 – 7.0). Patients treated with the combination of Ibandronate and systemic therapy were 2.3 times (95%CI: 1.7 – 3.2) more likely to obtain successful pain resolution, compared to untreated. Meta-regression showed no effect of heterogeneity length of follow-up or pain scales on the observed treatment effects. Heterogeneity in the network was considered moderate for overall survival and time to SRE, mild for SRE incidence, and low for pain resolution. While a generally high risk of bias was observed across studies, whether they were from Western or Chinese databases. The overall GRADE for the evidence underlying our results is High for Pain control and SRE incidence, and Moderate for OS and time to SRE.
This study represents the most comprehensive synthesis of the best available evidence guiding pharmacological treatment of bone metastases from lung cancer. Denosumab is ranked above ZA for both overall survival and time to SRE, but both treatments are superior to no treatment. ZA was first among all bisphosphonates assessed for odds of reducing SRE incidence, while the combination of Ibandronate and radionuclide therapy was most effective at significantly reducing pain from metastases. Clinicians and policy makers may use this synthesis of all available RCT data as support for the use of a BMA in MBD for lung cancer.
