Mortality following bone metastasis and skeletal-related events among women with breast cancer: a population-based analysis of U.S. Medicare beneficiaries, 1999–2006

Abstract

The aim of the study is to quantify the impact of bone metastasis and skeletal-related events (SREs) on mortality in older breast cancer patients. Using the linked Surveillance, Epidemiology and End Results-Medicare database, we identified women aged 65 years or older diagnosed with breast cancer between July 1, 1999 and December 31, 2005 and followed them to determine deaths occurring through December 31, 2006. We classified patients as having possible bone metastasis and SREs using discharge diagnoses from inpatient claims and diagnoses paired with procedure codes from outpatient claims. We used Cox regression to estimate mortality hazards ratios (HR) among women with bone metastasis with or without SRE, compared with women without bone metastasis. Among 98,260 women with breast cancer (median follow-up, 3.3 years), 7,189 (7.3%) had bone metastasis either at breast cancer diagnosis (1.5%) or during follow-up (5.8%). SREs occurred in 3,319 (46%) of women with bone metastasis. HRs for risk of death were 4.9 (95% CI 4.7-5.1) and 6.2 (95% CI 5.9-6.5), respectively, for women with bone metastasis but no SRE and for women with bone metastasis plus SRE, compared with women without bone metastasis. In analyses restricted to women with bone metastasis, the adjusted HR was 1.5 (95% CI 1.4-1.6) for women with bone metastasis plus SRE, compared with women with bone metastasis but without SRE. Having a bone metastasis, as indicated by Medicare claims, was associated strongly with mortality among women with breast cancer. This association was stronger for bone metastasis complicated by SRE than for bone metastasis without SRE.

Progress in the treatment of bone metastases in cancer patients

“…Among that population, 7.3% of patients developed bone metastases in the course of the disease, and SREs occurred in 46% of patients with bone metastasis. Compared with women without bone metastasis, hazard ratios for risk of death were 6.2 (95% CI: 5.9 --6.5) and 4.9 (95% CI: 4.7 --5.1) for women with bone metastasis with or without SRE, respectively [12]. Similarly as in breast cancer, occurrence of SRE in prostate cancer patients with bone metastases is strongly associated with decreased survival.…”

“…In the majority of studies published within the last decade, SRE included four types of events --pathological fracture, spinal cord compression, and a need for radiotherapy or surgery. The incidence of SRE is strongly associated with decreased survival among patients with bone metastases [11][12][13][14]. A population-based cohort study which included 35,912 patients diagnosed with first primary breast cancer from Danish National Patient Registry revealed that the 5-year survival rate was > 75% for patients without bone metastases, 8.3% for patients with bone metastases without SREs and 2.5% for those experiencing SREs.…”

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

“…Bone metastases are associated with lower survival in patients with advanced breast cancer and an increased risk of serious complications during the patients’ disease course 5, 6, 7. 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…”

Breast-Cancer Subtyping in Clinical Practice: Clinicopathologic Features and Outcomes

“…1,2 This type of cancer is considered to be a multifaceted disease and is characterized by a wide spectrum of clinical, pathologic, and molecular characteristics. 3 The heterogenous nature of these tumors present with variations in responses to therapy and outcomes.…”