Advances in Cancer Blood Clot Treatment

"I feel very lucky because I was told that the first sign of a pulmonary embolism is often death."
"If this research prevents people like me from developing blood clots, that will make a big difference for a lot of people."
"When I look back, I know I was lucky I survived."
Harold Black, 76, Ottawa cancer patient

"Cancer increases the risk of blood clots, which in turn can cause pain, reduce quality of life and increase the risk of death."
"Our study shows for the first time that we can safely prevent these clots in many people with cancer."
Dr. Phil Wells, chief of medicine, The Ottawa Hospital

"Anticoagulants are commonly used to prevent blood clots in other high-risk groups, but the traditional thinking has been that these drugs would cause too much bleeding in people with cancer." "Our study shows that if you select the right patients and use a relatively low dose of a direct oral anticoagulant, the benefits easily outweigh the risks."
Dr. Marc Carrier,  hematologist, associate professor, University of Ottawa, senior scientist, The Ottawa Hospital

People with cancer face an increased risk of blood clots in the legs (above) and lungs   The Ottawa Hospital

Cancer patient Mr. Black must now inject an anticoagulant daily to make certain there will be no recurrence of the blood clot in his lungs -- a pulmonary embolism -- following his bowel cancer surgery. This injection directed at his stomach is likely to be a constant for the rest of his life. He considers it a small price to pay for the assurance that another embolism will not occur.

Such blood clots are common complications from cancer and sometimes become deadly, representing in fact the second-leading cause of death for cancer patients; if the cancer doesn't kill them the resulting embolism could. Now, two Ottawa medical researchers have formulated a treatment regimen meant to prevent blood clots occurring in a high percentage of patients newly diagnosed with a solid type of cancer.

The results of a clinical trial undertaken by Dr. Phil Wells and Dr. Marc Carrier -- senior scientist and chief of medicine, and senior scientist and associate professor at The Ottawa Hospital respectively -- has seen publication in the New England Journal of Medicine. The blood clot program at The Ottawa Hospital and the University of Ottawa represents the largest, most research-intensive of its kind in the world.

As part of their research identifying cancer patients who face the greatest risk of developing clots, the researchers made use of a scoring system based on blood tests and allied factors. What they discovered is that roughly fifty percent of people starting chemotherapy for cancer placed in the high-risk group and would, as a result, benefit from preventive therapy.

Thirteen medical centres across Canada produced 563 patients involved in the clinical trial, identified as high risk for developing blood clots, half of whom were prescribed a placebo, the other half given a twice-daily oral dose of the anticoagulant drug apixaban. Slightly over ten percent of patients taking the placebo developed blood clots within a six-month period. In comparison, 4.2 percent of those given apixaban developed blood clots.

In the placebo group patients were slightly less likely to suffer a major bleed than those patients given the drug (one percent in comparison to 2.1 percent) but the bleeds were regarded as treatable. The strategy outlined in the research has the potential to prevent blood clots in up to 57,000 people in Canada and the United States at high risk of developing clots after a cancer diagnosis.