Incidence of bone metastases and skeletal-related events in breast cancer patients: A population-based cohort study in Denmark

Abstract

BackgroundBreast cancer (BrCa) is the most commonly diagnosed cancer among women in the industrialized world. More than half of women presenting with metastatic BrCa develop bone metastases. Bone metastases increase the risk of skeletal-related events (SREs), defined as pathological fractures, spinal cord compression, bone pain requiring palliative radiotherapy, and orthopaedic surgery. Both bone metastases and SREs are associated with unfavorable prognosis and greatly affect quality of life. Few epidemiological data exist on SREs after primary diagnosis of BrCa and subsequent bone metastasis. We therefore estimated the incidence of bone metastases and SREs in newly-diagnosed BrCa patients in Denmark from 1999 through 2007.MethodsWe estimated the overall and annual incidence of bone metastases and SREs in newly-diagnosed breast cancer patients in Denmark from January 1, 1999 to December 31, 2007 using the Danish National Patient Registry (DNPR), which covers all Danish hospitals. We estimated the cumulative incidence of bone metastases and SREs and associated 95% confidence intervals (CI) using the Kaplan-Meier method.ResultsOf the 35,912 BrCa patients, 178 (0.5%) presented with bone metastases at the time of primary breast cancer diagnosis, and of these, 77 (43.2%) developed an SRE during follow up. A total of 1,272 of 35,690 (3.6%) BrCa patients without bone metastases at diagnosis developed bone metastases during a median follow-up time of 3.4 years. Among these patients, 590 (46.4%) subsequently developed an SRE during a median follow-up time of 0.7 years. Incidence rates of bone metastases were highest the first year after the primary BrCa diagnosis, particularly among patients with advanced BrCa at diagnosis. Similarly, incidence rates of a first SRE was highest the first year after first diagnosis of a bone metastasis.ConclusionsThe high incidence of SREs following the first year after first diagnosis of a bone metastasis underscores the need for early BrCa detection and research on effective treatments to delay the onset of SREs.

Incidence proportions and prognosis of breast cancer patients with bone metastases at initial diagnosis

“…We also validated the results of survival analysis in another independent cohort from FUSCC. Some studies have evaluated the epidemiology and prognosis of breast cancer patients with bone metastases at the population level, but most of the patients in these studies presented bone metastases after a diagnosis of early‐stage breast cancer 2, 20, 29, 30, 31, 32, 33. However, limited data have been reported in the specific group of patients with bone metastases upon their initial diagnosis of breast cancer 34.…”

“…Globally, it accounted for approximately 1.67 million cases in 2012 and 0.52 million deaths, and both numbers have continued to increase 1. Approximately 5% of patients present with distant metastases at their initial diagnosis of breast cancer, with bone being the most common site 2, 3. Of those patients who die of breast cancer, approximately 70% will have evidence of bone metastases 4…”

“…The sites and extent of metastases determine the complications, which are called skeletal‐related events (SREs); these include pathological fractures, severe bone pain, bone marrow infiltration, spinal cord compression, and hypercalcemia 8, 9. The median time from bone metastases diagnosis to first SRE among breast cancer patients with bone metastases is only 1.8 months, and the 1‐year incidence of SREs is as high as 40% 2. Studies have demonstrated that nearly 50% of breast cancer patients with bone metastases experience at least one of these SREs, resulting in the reduced quality of life 2, 7, 10…”

“…The median time from bone metastases diagnosis to first SRE among breast cancer patients with bone metastases is only 1.8 months, and the 1‐year incidence of SREs is as high as 40% 2. Studies have demonstrated that nearly 50% of breast cancer patients with bone metastases experience at least one of these SREs, resulting in the reduced quality of life 2, 7, 10…”

Symptom Management in Metastatic Breast Cancer

“…In a Danish population-based cohort study, 4% of all breast cancer patients were diagnosed with bone metastasis either at the time of their initial breast cancer diagnosis or during follow-up (median follow-up, 3.5 years), and of those patients with a bone metastasis, Ͼ40% had a skeletal-related event (pathological fracture, spinal cord compression, or pain requiring palliative therapy) [75].…”