Venous thromboembolism (VTE) is a common complication in patients with cancer. In addition to surgery and prolonged hospital stays, chemotherapy is increasingly recognised as a risk factor for venous thromboembolism in patients with cancer. Evidence from RCTs concerning the clinical benefit of antithrombotic prophylaxis in ambulatory patients receiving chemotherapy for cancer is limited. The most recent guidelines state that further clinical trials are required before any recommendations can be made about the use of antithrombotic prophylaxis in ambulatory patients receiving chemotherapy for cancer.

Semuloparin is a hemisynthetic, ultra-lowmolecular- weight heparin with high anti-Xa activity and minimal anti-IIa activity. The SAVE-ONCO study assessed its efficacy and safety for prophylaxis against VTE in patients receiving chemotherapy for metastatic or locally advanced solid tumours.

Patients who were beginning to receive a course of chemotherapy were randomised to receive subcutaneous semuloparin, 20 mg once daily, or placebo until there was a change of chemotherapy regimen. The primary efficacy outcome was the composite of any symptomatic deep-vein thrombosis, any non-fatal pulmonary embolism, and death related to VTE. Clinically relevant bleeding (major and non-major) was the main safety outcome.

The following findings were reported:

• The median treatment duration was 3.5 months.

• VTE occurred in 20 of 1608 patients (1.2%) on semuloparin vs. 55 of 1604 (3.4%) on placebo (hazard ratio, 0.36; 95% CI, 0.21 to 0.60; p <0.001), with consistent efficacy among subgroups defined according to the origin and stage of cancer and the baseline risk of VTE.

• The incidence of clinically relevant bleeding was 2.8% and 2.0% in the semuloparin and placebo groups, respectively (1.40; 0.89 to 2.21).

• Major bleeding occurred in 19 of 1589 patients (1.2%) on semuloparin and 18 of 1583 (1.1%) on placebo (1.05; 0.55 to 1.99).

• Incidences of all other adverse events were similar in the two study groups.

The researchers conclude that the “results of this study show that thromboprophylaxis with the ultra-low-molecular-weight heparin semuloparin, as compared with placebo, reduces the risk of VTE among patients receiving chemotherapy for cancer, with no apparent increase in the incidence of major bleeding.”

An accompanying editorial discusses what these findings mean for patients and other health care decision makers, noting that “patients who are not bothered much by daily injections of low-molecular-weight heparin can probably avert hospitalisation for deep-vein thrombosis and pulmonary embolism and might live longer, if they accept an increased risk of bleeding and its subsequent treatment. Those truly seeking a survival benefit will need to deal with some uncertainty regarding whether the type and stage of their cancer are associated with the likely survival benefit provided by low-molecular-weight heparin.” It adds that “the key questions that are not answered conclusively relate to the effect of treatment with low-molecular-weight heparin on quality of life and whether such treatment affects tumour growth or dissemination. Most important, additional evidence is required as to which patients with cancer would receive the most benefit, what is the magnitude of the survival benefit, and is there a benefit for cancers that respond poorly to other therapies?”