Published February 15, 2012
Can the blood thinner heparin be effective in treating cancer?
In the Feb. 16 issue of the New England Journal of Medicine, researchers from UB and McMaster University suggest that conclusive answers about its benefits remain elusive despite promising results from large studies.
Elie Akl, MD, MPH, PhD, associate professor of medicine and family medicine at UB, co-authored the editorial with Holger Schünemann, MD, PhD, professor of medicine and chair of the Department of Clinical Epidemiology and Biostatistics at McMaster University, where Akl also holds an appointment.
Akl and Schünemann state that the anti-clotting effect of heparin is well established, unlike a speculated anti-tumor effect. Consequently, they question if it should be offered to cancer patients who don’t have clotting problems.
Their editorial comments on the largest study of its kind, which found that semuloparin—ultra-low molecular weight heparin—significantly reduced the incidence of thromboembolism but had no statistically significant effect on major bleeding and death.
Results of the SAVE-ONCO study also were published in the journal’s Feb. 16 issue.
The study involved 3,200 patients with metastatic or locally advanced solid tumors. Patients receiving chemotherapy also were given a preventative dose of semuloparin once daily for three and a half months.
Taken together with prior studies, the SAVE-ONCO findings confirm and further establish Akl’s and Schünemann’s conclusion of a “likely small survival benefit.”
If 1,000 patients with cancer were to use a prophylactic dose of low molecular weight heparin (LMWH), 30 would avert death, 20 would avert a clotting complication and one would suffer a major bleeding episode over a 12-month period, they estimated.
The study’s findings have implications for both patients and health care providers, the authors said.
“Patients who are not bothered much by daily injections of LMWH can avert hospitalizations for a clotting complication and possibly achieve a prolongation of life if they accept an increased risk of bleeding and its subsequent treatment.”
Key questions about the effect of LMWH treatment on patients’ quality of life and whether such treatment affects tumor growth or dissemination require further research, Akl and Schünemann noted.
For now, cancer patients need to deal with “some uncertainty” about whether their type and stage of cancer are associated with the likely survival benefit of this treatment. It’s unclear which cancer patients would benefit most, the magnitude of the survival benefit and whether patients who respond poorly to other therapies would benefit, they said.
The two physicians are planning a sophisticated analysis of the published trials, which will involve a meta-analysis of individual patient data, to investigate these questions.
Akl and Schünemann were invited to comment on the SAVE-ONCO study because they had previously summarized the available evidence on heparin in a 2011 Cochrane Review.
Their editorial is titled “Routine Heparin for Patients with Cancer? One Answer, More Questions.”