Symptomatic thromboembolic complications of central venous catheters (CVCs) occur in 5% or less of general oncology patients. Asymptomatic CVC-related thrombi are more common, but their clinical significance is unclear. Thrombotic risk may be increased by primary thrombophilic disorders, especially the factor V G1691A (Leiden) mutation, thrombogenic catheter material, larger catheter diameter and greater number of lumens, catheter tip malposition, left-sided placement, percutaneous or multiple insertion attempts, a previous CVC or preexisting venous obstruction, prothrombotic therapeutic agents, catheter-associated infections, and fibrinous catheter lumen occlusion. Three recent randomized, prospective, placebo-controlled trials observed no benefit of routine low-dose warfarin or low-molecular-weight heparin in preventing catheter-associated thrombosis. Nevertheless, thromboprophylaxis may be appropriate and safe for selected high-risk patients. Duplex ultrasound can accurately detect CVC-related thrombi involving the jugular, axillary, distal subclavian, and arm veins. Contrast venographic imaging is required for indeterminate duplex findings and to evaluate the deep central veins and pulmonary arteries. Therapeutic anticoagulation, with or without catheter removal, is indicated for patients with acute deep vein thrombosis (DVT) or pulmonary embolism who have no contraindications. Catheter removal alone, with close follow-up, may be sufficient when bleeding risk precludes safe anticoagulation. Approaches to managing catheter-associated thrombosis, including the use of thrombolytic agents, are guided by limited published experience and extrapolation from practices used for lower-extremity DVT. Prospective, randomized, controlled trials are needed to identify the safest and most effective anticoagulant agents, treatment durations, and alternative venous access strategies for cancer patients who develop catheter-associated thrombosis.
Michael L. Linenberger
C. Anthony Blau, Arturo B. Ramirez, Sibel Blau, Colin C. Pritchard, Michael O. Dorschner, Stephen C. Schmechel, Timothy J. Martins, Elisabeth M. Mahen, Kimberly A. Burton, Vitalina M. Komashko, Amie J. Radenbaugh, Katy Dougherty, Anju Thomas, Christopher P. Miller, James Annis, Jonathan R. Fromm, Chaozhong Song, Elizabeth Chang, Kellie Howard, Sharon Austin, Rodney A. Schmidt, Michael L. Linenberger, Pamela S. Becker, Francis M. Senecal, Brigham H. Mecham, Su-In Lee, Anup Madan, Roy Ronen, Janusz Dutkowski, Shelly Heimfeld, Brent L. Wood, Jackie L. Stilwell, Eric P. Kaldjian, David Haussler, and Jingchun Zhu
Accelerating cancer research is expected to require new types of clinical trials. This report describes the Intensive Trial of OMics in Cancer (ITOMIC) and a participant with triple-negative breast cancer metastatic to bone, who had markedly elevated circulating tumor cells (CTCs) that were monitored 48 times over 9 months. A total of 32 researchers from 14 institutions were engaged in the patient's evaluation; 20 researchers had no prior involvement in patient care and 18 were recruited specifically for this patient. Whole-exome sequencing of 3 bone marrow samples demonstrated a novel ROS1 variant that was estimated to be present in most or all tumor cells. After an initial response to cisplatin, a hypothesis of crizotinib sensitivity was disproven. Leukapheresis followed by partial CTC enrichment allowed for the development of a differential high-throughput drug screen and demonstrated sensitivity to investigational BH3-mimetic inhibitors of BCL-2 that could not be tested in the patient because requests to the pharmaceutical sponsors were denied. The number and size of CTC clusters correlated with clinical status and eventually death. Focusing the expertise of a distributed network of investigators on an intensively monitored patient with cancer can generate high-resolution views of the natural history of cancer and suggest new opportunities for therapy. Optimization requires access to investigational drugs.