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Got It, Hide thisDi Nisio M, Porreca E, Otten HM, et al. Primary prophylaxis for venous thromboembolism in ambulatory cancer patients receiving chemotherapy. Cochrane Database Syst Rev. 2014;8:CD008500.
In people who have cancer and are undergoing outpatient chemotherapy, do anticoagulant medications (“blood thinners”) prevent venous thromboembolism (blood clots in the veins)? Are they safe?
People who have cancer are more likely to develop blood clots in their veins, and this risk is higher when they are undergoing chemotherapy. These blood clots increase the risk of death. Anticoagulant medications can prevent blood clots, but they can also cause serious bleeding.
The researchers did a systematic review searching for published studies up to June 2013. They found 21 randomized controlled trials with 9861 people.
In the trials, people of any age had solid (tumour-based) or hematological (blood cell–based) cancer at any stage and were undergoing chemotherapy. They had not taken anticoagulant medications before.
Anticoagulant medications included low-molecular weight heparin (i.e., dalteparin [Fragmin®], certoparin, nadroparin, or enoxaparin [Lovenox®]); vitamin K antagonists (e.g., warfarin), unfractionated heparin, direct thrombin, or factor Xa inhibitors.
Anticoagulation medications were compared with a placebo or an inactive control.
Outcomes were symptomatic venous thromboembolism and major bleeding.
Quality of the trials ranged from low to high.
People had advanced or metastatic cancer in 14 of the 21 trials.
There was not enough evidence to assess vitamin K antagonists, unfractionated heparin, or direct thrombin or factor Xa inhibitors.
27 fewer people out of 1000 taking low-molecular weight heparin had symptomatic venous thromboembolism.
There was no effect of low-molecular weight heparins on major bleeding, but the quality of evidence was low.
In people who have cancer and are undergoing outpatient chemotherapy, low-molecular weight heparin reduces symptomatic venous thromboembolism.
Outcomes at 8 weeks to 4 years | Number of trials | Rate of events with low-molecular weight heparin | Rate of events with inactive control | Absolute effect of anticoagulant medications | Quality of the evidence |
Symptomatic venous thromboembolism | 8 | 2.7% | 5.8% | 27 fewer people out of 1000 had a venous thromboembolism | Moderate |
Major bleeding | 8 | 2.4% | 2.2% | No effect* | Low |