Cancer increases blood clot risk

Reported by Susan Aldridge, PhD, medical journalist

A study shows that patients with cancer have a seven fold increased risk of developing a blood clot in the lungs or legs.
Researchers at Leiden University Medical Center in The Netherlands have been looking at some of the risk factors for venous thrombosis in the legs and pulmonary embolism. They studied a group of 3,220 patients attending an anticoagulant clinic and a group of over 2,000 controls.

People with cancer had over seven times the risk of developing a clot. The risk was highest among those with a blood, lung or gastrointestinal cancer. And the clot was most likely to develop within a few months of the cancer diagnosis. Those who had secondary cancers were also especially at risk.

The researchers also carried out DNA analyses for mutations known to increase clotting. Those with a mutation called Factor V Leiden were more likely to develop a clot and having cancer magnified this risk. It may be worth offering patients with cancer anticoagulant therapy; the researchers believe this might be more cost effective than screening them for mutations.

Source
Journal of the American Medical Association 9th February 2005 Volume 293 pages 715-722