乌鸦传媒

ORLANDO -- Patients who need anticoagulation therapy after a cancer-associated thrombosis can safely switch to warfarin from low molecular-weight heparin (LMWH) after 6 months, a researcher said here.

In a retrospective analysis of more than 1,500 patients, those who switched to oral warfarin from injectable LMWH had no increase in the risk of recurrent venous thromboembolism (VTE), according to Chatree Chai-Adisaksopha, MD, of in Hamilton, Ontario.

The warfarin patients also had no increase in the risk of major bleeding, Chai-Adisaksopha said during a press conference at the American Society of Hematology (ASH) meeting.

The study is important because it assures clinicians that choosing warfarin -- as many do -- is not harmful, commented , of Erasmus University Medical Center in Rotterdam, The Netherlands, who co-moderated an ASH oral session.

"It's daily practice; it's what we do," she told 乌鸦传媒. "It's good to see some data on what we do and whether it's a good thing."

Many cancer patients need anticoagulation treatment, and guidelines recommend 6 months of LMWH, commented , of the Ottawa Hospital Research Institute in, the other ASH co-moderator.

But what happens after that is up in the air, he told 乌鸦传媒. "After 6 months we have very little data. but consensus says patients will still need some form of anticoagulation."

For some patients, warfarin can be an attractive option, Carrier said. "You can imagine that after 6 months people are tired of self-injecting [LMWH] and switching to an oral agent would be appealing."

On the other hand, the issue might soon be moot as newer anticoagulants, such as the , move into the clinic. These drugs can be used with less intensive monitoring than warfarin so the current trial results are "a little bit of old news," Carrier said.

Chai-Adisaksopha and colleagues turned to the international (RIETE), which enrolls patients with a cancer-associated thrombosis.

They looked at records at 1,502 consecutive patients who completed 6 months of LMWH after their diagnosis of thrombosis and divided them into two groups -- 763 who continued on LMWH and 739 who switched to warfarin.

The primary endpoint of the analysis was the time to recurrence of an objectively confirmed thrombotic event, either a deep vein thrombosis or pulmonary embolism. The main secondary endpoint was the rate of major bleeding.

The patients were followed for a median of 11 months after the initial diagnosis, and the two groups were well matched for most characteristics, although not randomly selected. The exceptions were a higher rate of lung cancer and metastatic disease among patients who continued on LMWH.

They were also well matched in terms of clinical characteristics, such as the type of thrombosis, history of major bleeding in the month before diagnosis, and concomitant antiplatelet use, the investigators found.

The analysis showed no significant difference between the arms in the proportion of patients reaching the primary endpoint:

• 55 patients in the LMWH arm and 44 in the warfarin arm had a recurrent VTE, of 7.2% and 6%, respectively.
• Three patients in the LMWH arm and four in the warfarin arm died of the VTE, or 0.4% and 0.5%, respectively.

Also, the cumulative incidence of major bleeding was 2.6% percent in the LMWH group and 2.7% in those who had warfarin, while total bleeding rates were 6.7% and 7%, respectively.

Studies suggest that the critical period for a recurrent VTE or major bleeding is within 6 months of the first, Chai-Adisaksopha said, an idea supported by the current study.

He noted that the study was limited by a lack of randomization and there may have been confounding factors that weren't taken into account. Prospective studies are needed to confirm the results, he said.

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