People with cancer have an increased risk of developing blood clots, with roughly one in five experiencing venous thromboembolism (VTE) — blood clots that occur in deep veins like the legs or that travel through the blood stream and get lodged in the small blood vessels in the lungs.

International guidelines recommend treatment using low-molecular-weight heparin, an anticoagulant that is injected subcutaneously; however, new results from a large pilot trial suggest that DOACs, newer blood thinners administered as a daily pill, could be a safe and beneficial alternative for treating VTE in selected patients.

Although there are many causes and risk factors for VTE, its increased prevalence in cancer patients is thought to be related to a combination of factors such as immobility from remaining in bed, procoagulants produced by the tumour, and chemotherapy.

Because VTE can be life-threatening, blood thinners are used to shrink existing clots and prevent others from forming.

The select-d trial enrolled 406 patients who had cancer and VTE; most (69 percent) were receiving cancer treatment (typically chemotherapy) at the time of their VTE.

Half were randomly assigned to receive low-molecular-weight heparin (dalteparin) and half were assigned to receive a DOAC (rivaroxaban).

After six months of treatment, the VTE recurrence rate was four percent among those receiving the DOAC and 11 percent in those receiving dalteparin.

The results for secondary outcomes were mixed.

In patients receiving the DOAC, there were more major bleeding events (11 patients) and a marked increase in clinically relevant non-major bleeds (25 patients) compared to those taking heparin (6 and 6 patients, respectively).

The researchers are conducting further analyses to try to understand factors that may have contributed to this difference.

“Clinicians are already adopting DOACs into practice for these patients,” said lead study author Annie Young, PhD, Professor of Nursing at the University of Warwick, “and now they have data from this study to indicate that DOACs are potentially safe in cancer patients. We need to be looking at different groups of people and different types of bleeds in more detail, so that we can choose the best treatment for each patient.”

Source: ASH 2017