For years, medical researchers have noticed that blood clots may be a prelude to cancer. At the same time, men who taking blood thinners for several months, according to a Sweish study last year, seemed to be protected against developing prostate cancer. This finding, though, has been questioned on the basis of older clinical trials. Now the San Diego team has come up with a new theory and new evidence. This work shows that the early phase of these interactions is crucial for metastasis a process in which tumor cells from the primary site enter the bloodstream, travel to distant tissues and establish new tumors.
Unchecked metastasis is what makes cancer a fatal disease.
The researchers, who report their work in the March 13 issue of the Proceedings of the National Academy of Sciences, say their findings make a compelling argument for initiating clinical trials of heparin in patients with newly diagnosed cancer. However, our new findings suggest that heparin therapy to prevent the spread of cancer in humans should be revisited, with a completely new paradigm in mind. Animal studies in the 60s and 70s showed that heparin which is delivered by injection or intravenously inhibits metastasis. Other mechanisms for the heparin effect have since been suggested, but not proven. Follow-up human studies focused instead on the use of oral anticoagulants, which are easier to manage than heparin.