The Catheter Study: Central Venous Catheter Survival in Cancer Patients Using Low Molecular Weight Heparin (Dalteparin) for the Treatment of Deep Vein Thrombosis

Deep venous thrombosis (DVT) is a serious disorder with an annual incidence of approximately 0.1% and increasing with age to 1% in the elderly. Deep venous thrombosis of the upper extremity (UEDVT) is estimated to constitute 1-5% of all cases of DVT.

The therapy of UEDVT has not been standardized.Therapeutic options include anticoagulation with unfractionated heparin followed by warfarin, treatment with a thrombolytic agent, or a thrombectomy. Recently, treatment with low molecular weight heparin has been shown to be a safe and effective treatment for patients with verified UEDVT.

In patients with cancer, treatment of UEDVT associated with central venous catheters is even less standardized. Some groups advocate removal of the catheter as the sole treatment for the DVT, others remove the catheter and treat the DVT. A major disadvantage to removing the line is that often re-insertion in the opposite limb is then required to avoid disruption of chemotherapeutic treatment. This reinsertion again puts the patient at risk for thrombosis and pulmonary embolism. Another therapy is treatment only with systemic thrombolytic therapy. The disadvantage of thrombolytic therapy in persons with cancer is that there is a high risk for major bleeding at the doses used.

A treatment regimen that has been adopted by the London Health Sciences Centre, and others across Canada, is to leave the catheter in place and treat the DVT with low molecular weight heparin and warfarin. This regimen is believed to halt the progression of thrombi, prevent embolism and allow natural thrombolytic mechanisms to work effectively. By leaving the central line in situ and appropriately treating the thrombosis there is no disruption in the delivery of life-prolonging or life-saving treatment in the form of chemotherapy.

Preliminary data has been collected over the past 24 months at the London Health Sciences Centre; the results suggest that this approach to treatment will prove to be beneficial to the patient. Thirteen (13) patients with cancer and an UEDVT associated with a central venous catheter were treated with dalteparin and warfarin with an intention to leave the central line in situ. Of the 13, 1 patient had the line removed after 3 days at a peripheral hospital against recommendation. The UEDVT was treated successfully and without the need for line removal in 9 (75%) of the remaining 12 patients. Two (2) of the 12 had lines removed at 1 week and 1 had the line removed at 4 weeks due to worsening symptoms of UEDVT.

Therefore, UEDVT is a more common and less benign disease than previously reported and generally arises in the presence of recognizable risk factors such as central venous catheters and cancer. Treatment of the UEDVT with dalteparin and warfarin will treat the thrombosis while preserving the central venous access for continued use. Hence, the need for additional catheters and subsequent risk of bilateral UEDVT will be minimized.

Result of the CLOT (Clot in Cancer) Trial have shown the superiority of treatment with dalteparin for 6 months as compared to the conventional treatment with short-term dalteparin and extended warfarin for cancer patients with acute symptomatic DVT or PE. Extended anticoagulant therapy may be beneficial in patients with UEDVT as well, however, there are currently no estimates of clinical outcomes for either conventional (dalteparin followed by warfarin) or extended therapy with dalteparin in this patient population.

Inclusion criteria

• Males or females greater than or equal to 18 years of age, inclusive.
• Symptomatic acute upper limb thrombosis with or without pulmonary embolism associated with central venous catheter objectively documented by compression ultrasonography, venogram or computed tomography (CT) scan.
• Diagnosis of active malignancy, as defined by patients who are either receiving active treatment, or have metastatic disease or who have been diagnosed within the past two years.
• Willing to provide written informed consent.

Exclusion criteria

• Dialysis catheters.
• Active bleeding or high risk for major bleeding.
• Platelet count < 100 x 10x9/L.
• Serum creatinine > 177umol/L
• Currently on warfarin with therapeutic intent (does not include minidose warfarin used as prophylaxis for CV catheter thrombosis).
• Pulmonary embolism accompanied by hemodynamic instability or oxygen requirement.
• Inability to infuse through the catheter after a trial of intraluminal thrombolytic therapy.
• Patients with acute myelogenous leukemia (AML) or acute lymphoblastic leukemia (ALL) with a bone marrow or stem cell transplant pending in next 3 months.