New Blood Thinners and Cancer Patients

Doctor holding a blood sample.

Since 2010, the US FDA has approved four new oral anticoagulant drugs – Pradaxa (dabigatran), Xarelto (rivaroxaban), Eliquis (apixaban), and Savaysa (edoxaban). These blood thinners are currently used to prevent blood clots from forming and causing harmful blockages in people who are at risk. However, these agents have not been studied specifically in people with cancer.

Here, the two conditions for which the most data exists are examined first, before moving on to patients with cancer.

New Oral Blood Thinners

On the positive side, for specific groups of patients, they generally do the job of preventing strokes and dangerous blood clots as well as -- or better than -- the older standard, warfarin (Coumadin). Of particular note, the four new drugs were substantially less likely than warfarin to cause a particular kind of bleeding leading to stroke – a “hemorrhagic stroke,” a stroke caused by bleeding into the brain, which is different from the strokes caused by the clots that go to the brain in atrial fibrillation.

The new blood thinners also offer the freedom from the need to have periodic blood test monitoring. They are more expensive than the conventional alternative, and some payers -- insurance companies and HMOs – have been resistant to pay for them.

These blood thinners are not for everyone, and there are concerns about risk of bleeding, as there are with all anticoagulants; unlike the old stand-by, however, these newer blood thinners cannot be quickly and easily reversed, so that is an added consideration.

While many people with two specific conditions -- atrial fibrillation and DVT/PE – now use the new oral blood thinners, the role of these agents is not as clear for people with cancer.

Atrial Fibrillation

An estimated 2.7–6.1 million people in the United States have atrial fibrillation. When the heart goes into this abnormal rhythm, clots can form and travel to the brain, blocking blood flow, causing stroke.

Blood thinners help prevent this from happening. For people with a subset of this disease called nonvalvular atrial fibrillation, the new agents offer the benefits of being on an anticoagulant – that is, reduced rates of stroke -- without the hassle of outpatient lab monitoring.

DVT/PE

As many as 900,000 people could be affected by DVT/PE each year, according to the CDC. DVT/PE actually refers to two separate things. Deep vein thrombosis (DVT) is a medical condition that occurs when a blood clot forms in a deep vein. These clots usually develop deep in the lower leg, thigh, or hip area, but they can occur elsewhere. The most serious complication of DVT happens when a part of the clot breaks off and travels through the bloodstream to the lungs, causing a blockage called pulmonary embolism (PE). You can have a PE without having a DVT. Pulmonary embolism is potentially life threatening, although some PEs are so small that people never know they have occurred. Newer oral anticoagulants can be used for DVT/PE.

In clinical practice, heparins are still routinely used for the initial treatment of acute DVT or PE. Switching to an oral blood thinner, however, can help to return a patient home from the hospital when the time is right.

Blood Thinners for Cancer Patients

The new blood thinners were studied in people with atrial fibrillation or DVT/PE, and not cancer. The relationship between cancer and thrombosis, or blood clots, is complex and some areas are not completely understood. While there is now some information about people with cancer who have been on the new blood thinners, there is not much in the way of science or data -- especially long-term data -- for doctors to go on, and thus there is some caution and concern.

How does this translate into practice? Well, let's say you have been taking Xarelto for nonvalvular atrial fibrillation, and then you receive a diagnosis of cancer. Do you stay on Xarelto for your afib? The answer, it turns out, can be a complicated one.

In an article in the January 2014 issue of the journal “The Oncologist,” Dr Jean Connors and Dr Nicholas Short put things in perspective as follows:

“In absence of safety and efficacy data of the [new blood thinners] in cancer populations, these agents should be used with caution in patients with active malignancy only after careful evaluation of the risks and benefits for individual patients.” Other sources recommend also seeking the additional input of a cardiologist in making a decision that involves multiple specialties within medicine.

In short, while these agents have been shown to work in preventing or treating blood clots in patients with cancer and critical illness, their role in these situations is not yet clear. The need for anticoagulation in people with cancer is a common one. However, low molecular weight heparin or fractionated heparin has been preferred for preventing venous blood clots, or venous thromboembolism. For now, a case-by-case approach to the new blood thinners seems to be in effect for people with cancer.

Sources

January CT, Wann LS, Alpert JS, Calkins H, Cigarroa JE, Cleveland JC Jr, Conti JB, Ellinor PT, Ezekowitz MD, Field ME, Murray KT, Sacco RL, Stevenson WG, Tchou PJ, Tracy CM, Yancy CW. 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2014;64:2246–80.

Peacock WF, Levy PD, Gonzalez MG. Target-specific Oral Anticoagulants in the Emergency Department.  J Emerg Med. 2015;S0736-4679(15)01037-9.

Short NJ, Connors JM. New Oral Anticoagulants and the Cancer Patient. The Oncologist. 2014;19(1):82-93.

Roca B, Roca M. The new oral anticoagulants: Reasonable alternatives to warfarin. Cleve Clin J Med. 2015;82(12):847-54.

Cohen AL, Lim CS, Davies AH. Is there a role yet for new direct oral anticoagulants in cancer patients? Phlebology. 2015 pii: 0268355515604255. [Epub ahead of print]

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