Men with prostate cancer are at increased risk of potentially life-threatening thromboembolism (formation of a blood clot), particularly those receiving endocrine therapy (hormone therapy). The Article published Online First in the Lancet Oncology is the first to show in detail an association between prostate cancer and thromboembolic disease.
It is well established that cancer increases the risk of thromboembolism, although the underlying mechanisms involved are not fully understood. Indeed, patients with cancer are about four times more likely to develop a thrombosis (blood clot) than healthy individuals. But little is known about the specific association between prostate cancer and thromboembolic disease. However, previous research has suggested a greater likelihood of developing thromboembolic disease after endocrine therapy, an increasingly common treatment in men with prostate cancer.
To provide more evidence, Mieke Van Hemelrijck from King's College London, London, UK, and international colleagues assessed the risk of thromboembolic disease (deep vein thrombosis [DVT], pulmonary embolism, and arterial embolism) in Swedish men with prostate cancer receiving different types of treatment compared with Swedish men in the general population. The investigators used data from PCBaSe Sweden, which is based on the National Prostate Cancer Register (NPCR) of Sweden*.
Between 1997 and 2007, 30642 men received endocrine therapy, 26432 curative treatment, and 19526 surveillance. A total of 1881 thromboembolic events were reported and analysed.
Overall, findings showed that men with prostate cancer were significantly more likely to develop thromboembolic disease than men without prostate cancer. All three treatment groups were at increased risk of DVT and pulmonary embolism, but not arterial embolism.
Additionally, men receiving endocrine therapy had the highest risk of venous thromboembolism. Patients undergoing endocrine therapy were two-and-a-half times more likely to have a DVT (SIR 2•48) than the general population, and nearly twice as likely to experience a pulmonary embolism (SIR 1•95)**. This risk was especially high for younger men (<65 years) and men with advanced disease. Subset analyses showed a smaller increased risk of venous thromboembolism in patients treated with anti-androgens compared with other types of endocrine treatment.
The authors suggest that this increased risk of thromboembolic disease is likely to be the result of the cancer itself (eg, advanced cancer is a risk factor) and/or the treatments and factors taken into account during the process of selecting these treatments (eg, curative treatment, such as prostatectomy and advanced age are associated with an increased risk).
The authors conclude: "Our findings indicate that it is important to consider thromboembolic side-effects when treating patients with prostate cancer, especially those who require endocrine treatment."
In an accompanying Comment, Philip Saylor and Annemarie Fogerty from Massachusetts General Hospital Cancer Center, Boston, USA, say that this study: "provides an important population-based analysis of clotting in a large cohort of Swedish men with prostate cancer. The data should increase clinical suspicion for VTE in men with prostate cancer and stimulate further study of the potential interactions between androgen deprivation and blood coagulation."
Contacts: Miss Mieke Van Hemelrijck, King's College London, London, UK. T) +44 (0)207 188 9286 E) mieke.vanhemelrijck@kcl.ac.uk
Dr Philip Saylor, Massachusetts General Hospital Cancer Center, Boston, USA. T) +1 858 354 9786 (mobile) or +1 617 724 4000 (page through MGH operator) E) Philip_Saylor@DFCI.HARVARD.EDU
For full Article and Comment, see: http://press.thelancet.com/tlobloodclots.pdf
Notes to Editors:
*The NPCR of Sweden was started in 1996 and records more than 96% of all newly diagnosed prostate cancers and provides complete follow-up for each patient. For their analyses, the researchers used data on age, serum concentrations of PSA, treatment information at time of diagnosis, tumour grade and stage, socioeconomic status, history of thromboembolic disease, and rate of death.
**Standard incidence ratios (SIRs) were calculated by comparing the observed number and expected number (using the total Swedish male population) of occurrences of thromboembolic diseases.
Journal
The Lancet Oncology