Are blood clots a concern in cancer patients?

Cancer patients are at increased risk to develop blood clots.  In fact, compared to a non-cancer patient, the risk is 5-7 times higher, with the highest risk in the first 3-6 months after cancer diagnosis.  Cancer chemotherapy further increases the risk of developing a blood clot by 7.3-13.5% in the twelve months following initiation of therapy.  This pie chart shows causes of fatality in patients with cancer.  After cancer itself,  blood clots are tied with infection as the second most common cause of death in this group.   

Are some cancers more likely than other to cause a blood clot?

Some cancers are many times more likely than others to induce a blood clot.  Some cancers associated with a higher risk of clotting are pancreatic, stomach, brain, lung, colorectal, ovarian, and bladder cancers.  

Are blood clots in cancer patients more difficult to treat?

Blood clots formed in cancer patients are much more dense.  The standard of care for cancer patients with a blood clot is a daily injection of low molecular weight heparin (LMWH) under the skin for several months and even lifelong treatment in some cases.

This video has a lot of great information about blood clots and cancer.  This and many other resources are available at the Thrombosis Canada website.

Does pregnancy increase the risk of a clot?

Pregnancy does increase the risk of developing a blood clot.  In a healthy individual, the risk of having a clot during pregnancy is five times greater, at 0.5 in 1000 pregnancies.  When other risk factors are present, this risk can increase further.  A small dose of low molecular weight heparin administered daily can prevent a blood clot.  The 2014 SOGC guidelines suggest that once the risk of a clot exceeds 1%, LWMH should be prescribed.

Which patients are more likely to have a blood clot during their pregnancy?

Patients who have had  previous blood clot are at increased risk of having another one during pregnancy.  Some patients may not have had a blood clot, but have a predisposition to developing blood clots.  This is referred to as a thrombophilia.  Some are higher risk than others, such as antithrombin deficiency, antiphospholipid syndrome, homozygous factor V Leiden or prothrombin gene mutation 20210A.  It is possible to have more than one thrombophilia, which also increases risk of a clot.

Want to learn more about the cause of blood clots, their treatment, and prevention?  Created by patients, for patients, this is a great resource.

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