[Long-term treatment of venous thromboembolism in patients with cancer].

Background: The treatment with low-molecular-weight heparin (LMWH) is recommended for patients with cancer associated thrombosis (CAT) during the first 6 months; the initial therapeutic dose can be reduced to 60-75 % after one month. The therapy should be reevaluated after 6 month and subsequent therapy using LMWH or warfarin is recommended indefinitely, unless the cancer is resolved or any major contraindications arise.

Aims: To analyze the usage of various treatment modalities in CAT patients after the initial 6 month period according to the course of cancer.

Patients And Methods: 87 patients with CAT were followed prospectively during the treatment period. The proportion of patients, in whom LMWH was replaced by warfarin during the first 6 months and during the entire follow up, was analyzed in relation to the course of the cancer. The χ2 test and χ2 test with Yates correction were used for the statistical evaluation.

Results: The median follow-up was 445 days, mean duration of follow up was 743 days. 6 months after the diagnosis of thrombosis 9/30 (31.0 %) patients with complete remission (CR) of the cancer were treated with warfarin, while only 3/12 (25 %), 0/9 (0 %) and 1/13 (7.7 %) of the patients with partial remission (PR), stable disease (SD) and progression, respectively, were treated with warfarin. Patients with CR and PR were more frequently treated with warfarin than patients with SD or progression (P = 0.02). 13 patients died during the first 6 months, and 8 patients were followed less than 6 months. During the entire follow up, 25/30 (83.3 %) patients with CR switched to warfarin, while only 5/12 (41.7 %), 1/9 (11.1 %) and 1/13 (7.7 %) patients with PR, SD, and progression, respectively, were treated with warfarin. The proportion of patients with CR which switched to warfarin was higher, than the proportion of patients with PR (P = 0.007), with SD (P = 0.0003), and with progression (P < 0.0001). Median time from thrombosis onset to the switch from LMWH to warfarin was 219 days in patients in complete remission after 6 months and was not reached in patients in PR,SD, and progression.

Conclusions: The course of malignant disease is important for the choice of appropriate therapy of CAT after the initial period of LMWH therapy. The patients achieving complete remission are more prone to switch from LMWH to warfarin.

Key Words: cancer - low-molecular-weight-heparin - venous thromboembolism - warfarin.