The prognostic significance of bone metastases and skeletal-related events (SREs) in prostate cancer survival: A population-based historical cohort study in Denmark (1999–2007)

Abstract

5160 Background: Common among advanced prostate cancer patients, bone metastases indicate cancer progression and poor prognosis but few studies have quantified their influence on patient survival, particularly in the presence of subsequent skeletal-related complications. We therefore sought to examine this in a large population-based cohort of prostate cancer patients. Methods: Using data from the Danish National Patient Registry (covering all Danish hospitals), we studied 23,087 patients diagnosed with prostate cancer between 1999 and 2007, with follow-up through April 2008 (median follow-up: 2.2 years). We estimated the incidence of bone metastases following cancer diagnosis and the subsequent occurrence of SREs (radiation and surgery to the bone, fracture, spinal cord compression). We then computed and compared survival for three prostate cancer subgroups - no bone metastases, bone metastases, and bone metastases with SREs - using Kaplan-Meier and multivariate Cox proportional hazards models. Results: Across the study period, 14% (n = 3,261) of the prostate cancer patients developed bone metastases: 6.8% (n = 1,570) had bone metastases and no SRE and 7.3% (n = 1,691) had both bone metastases and at least one SRE (radiation to the bone was most frequent). One-year survival was lowest for prostate cancer patients with bone metastases and SREs (40%) compared to the groups with no bone metastases (87%) and with bone metastases but no SREs (47%). Similarly, after adjusting for age and the presence of comorbidities, short-term prognosis was poorest in patients with both bone metastases and SREs: compared to prostate cancer patients with no bone metastases, the 1-year mortality rate was 6.7 times greater for those with bone metastases and SREs (95% confidence interval (CI): 6.0–7.6) versus just 4.7 times higher in those with only bone metastases (95% CI: 4.3–5.2). Less than 1% of prostate cancer patients who developed bone metastases and suffered any SRE survived beyond five years. Conclusions: Although the presence of bone metastases confers a short-term prognosis in prostate cancer patients, survival is even poorer for patients who also experience skeletal-related complications. [Table: see text]