AT EHA 2017
MADRID – Look before you leap into anticoagulation therapy for older cancer patients, results from a Canadian cohort study suggest.
Among patients 65 and older with cancer and a venous thromboembolic event (VTE) within 6 months of the cancer diagnosis, the 7-day mortality rate from VTE was 0.5%, compared with an 11% rate of death from a major bleeding episode, reported Alejandro Lazo-Langner MD, MSc from Western University in London, Canada.
“We conclude that the use of anticoagulants in cancer patients that are 65 or older with thrombosis, if they bleed, this results in at least a nine times higher mortality rate than if they had thromboembolic recurrence,” he said at a briefing at the annual congress of the European Hematology Association.
If their findings are confirmed in further studies, “it would actually change what we do in terms of the treatment of thrombosis,” he said.
Risks for both VTE and for bleeding are known to be higher among patients with cancer than in the general population. Although a previously published systematic review suggested that mortality rates from recurrent VTE and major bleeding events were similar in the first 6 months of anticoagulation therapy, those results were limited by the heterogeneity of designs in the various studies included in the review, and by differences in outcome measures and the types of populations included, Dr. Lazo-Langner said.
To get a better idea of the case fatality rates of VTE recurrence and major bleeding and the case fatality rate ratio for each, the authors conducted a retrospective population-based cohort study in the Province of Ontario using de-identified linked administrative health care databases.
They assembled a cohort of patients 65 years of age and older who had a VTE event within 6 months of an initial cancer diagnosis. Recurrent VTE and major bleeding events were assessed within 180 days of the index date.
They found that from 2004 through 2014 there were 6,967 VTEs in cancer patients over 65 years of age (mean age 75) that were treated with an anticoagulant, either low-molecular-weight heparin (LMWH), LMWH plus warfarin, warfarin alone, or rivaroxaban (Xarelto).
Six months after the index VTE events, 235 patients (3%) had experienced a major bleeding event, and 1,184 (17%) had a recurrent VTE.
Within 7 days of the outcome event the mortality rate due to major bleeding was 11%, compared with 0.5% for recurrent VTEs. This translated into a mortality rate ratio for major bleeding vs. VTE of 21.8
The investigators conducted an exploratory analysis to see whether there could be differences in mortality rates according to the type of anticoagulant prescribed, but could not find any.
Elizabeth Macintyre, MD, from the Hôpital Necker-Enfants Malades and University of Paris, France, who was not involved in the study, said in an interview that the results indicate that clinicians should not automatically assume that anticoagulation is a good idea for every older cancer patient.
“We now need to consider whether we should be reducing the time of anticoagulation, but that obviously depends on all sorts of other risk factors, so it has to be an individual patient decision. But the message is clearly don’t just anticoagulate to avoid the risk of thrombosis, and do in bear in mind that the other side of the coin could be just as serious,” she said.
The study was supported by the Institute for Clinical Evaluative Sciences, funded by an annual grant from the Ontario Ministry of Health and Long-Term Care. Dr. Lazo-Langner and Dr. Macintyre reported having no conflicts of interest to disclose.
