There is a health threat for patients with cancer that doesn’t get as much attention: blood clots in their veins. Blood clots can break off and move to other parts of the body including the lungs. A blood clot in the lung can be life-threatening. One estimate says as many as one in five cancer patients will develop clots in their veins.
Why do many cancer patients develop blood clots? The reasons are not totally clear but it is known that some cancers produce substances that can promote the creation of clots. Cancer also increases inflammation, and compresses blood vessels, which increases the risk for developing clots. Not all cancer patients are threatened by blood clots. Patients with pancreatic, lung cancer, multiple myeloma, or other blood cancers are more likely to develop clots.
Now there is encouraging news for patients at risk. Two studies presented at the American Society of Hematology meeting in San Diego found that one kind of drug can reduce the risk of blood clots in patients with cancer. And the drug is viewed as a significant improvement on the current treatment.
The first study, known as AVERT, was done by researchers from the University of Ottawa, and published simultaneously in the New England Journal of Medicine. In the AVERT study, 574 patients who were newly diagnosed or had progression of a known cancer and were starting a new course of chemotherapy were randomly assigned to either the drug apixaban (Eliquis) or placebo and followed for 180 days. The results:
- 12 (4.2%) of 288 patients taking apixaban developed clots
- 28 (10.2%) of 275 patients on placebo developed clots
Statistically that’s an important result. Patients taking the drug had significantly fewer clots. But drugs that prevent clots also increase the risk for bleeding. In the AVERT study, more patients taking the drug had episodes of major bleeding during the 180 days of the study.
- 10 (3.5%) with apixaban had major bleeding
- 5 (1.8 %) in placebo group
Apixaban is part of a new class of drugs called novel anticoagulants or NOACs which are widely used in the treatment of patients with an irregular heartbeat that increases the risk of stroke. The NOACs are an alternative to Heparin, the standard treatment for cancer patients at risk for blood clots. Heparin involves twice daily injections which can be painful, costly, and produce numerous side effects ranging from dietary restrictions to a serious clotting disorder. Heparin also requires regular monitoring with a blood tests to make sure the dose is correct.
All these drawbacks to Heparin and similar drugs has led to NOACs becoming the preferred choice for doctors treating heart patients. Now there are numerous studies of these drugs in cancer patients. NOACs generate billions in sales for drug companies in heart patients, and the studies presented at the American Society of Hematology may lead to important approvals of these drugs in cancer patients. Right now, unless they are in a clinical study, cancer patients don’t get NOACs.
The second study of apixaban actually compared it to Heparin. According to a release from the Mayo Clinic, apixaban was associated with “fewer major bleeding events and fewer recurrent blood clots, compared to low-molecular- weight heparin.” The study author Robert McBane II M.D., a Mayo Clinic cardiologist, said quality-of-life surveys showed that cancer patients preferred apixaban.
Regardless of the treatment, cancer patients need to know about their higher risk of developing blood clots. An article from the Dana Farber Cancer Institute outlines the symptoms which include “cramping and pain in the legs, similar to that of a Charlie horse, or unexplained swelling. Those with pulmonary emboli may experience difficulty breathing, back or chest pain, or coughing.”
To decrease the risk of getting blood clots “avoid staying seated for long periods of time, particularly during long car or airplane travel. Change position and take short walks when possible to keep your blood flowing. Tell your oncologist or surgeon if you have had blood clots in the past, and let them know if you have any close relatives (parents or siblings) who have a history of blood clots, particularly before the age of 50.”
The American Society of Clinical Oncology (ASCO) has provided guidance for patients. ASCO says there are also non-drug approaches to treatment which include “graduated compression stockings, which are a type of support hose and intermittent pneumatic compression, which is squeezing the legs through a sleeve connected to a machine.” ASCO has a number of recommendations on which patients should be treated:
- Most patients with cancer who are in the hospital should receive treatment with an anticoagulant to prevent blood clots during their hospital stay.
- Many patients who have to stay in the hospital for just a few days, such as for a minor procedure, do not need blood clot prevention, except for those patients who have a high risk of blood clots.
- Patients who will have major surgery for cancer should receive treatment to prevent blood clots before surgery, continuing for at least seven to ten days after surgery. Treatment may continue for up to four weeks for patients who have a higher risk of blood clots.