A feasibility study to inform the design of a randomized controlled trial to identify the most clinically and cost effective Anticoagulation Length with low molecular weight heparin In the treatment of Cancer Associated Thrombosis (ALICAT): study protocol for a mixed-methods study

BACKGROUND Venous thromboembolism is common in patients with cancer and requires anticoagulation with low molecular weight heparin. Current data informs anticoagulation as far as six months, yet guidelines recommend anticoagulation beyond six months in patients who have locally advanced or metastatic cancer. This recommendation, based on expert consensus, has not been evaluated in a clinical study. ALICAT (Anticoagulation Length in Cancer Associated Thrombosis) is a feasibility study to identify the most clinically and cost effective length of anticoagulation with low molecular weight heparin in the treatment of cancer associated thrombosis. METHODS/DESIGN ALICAT is a randomized multi-centre phase two mixed-methods study with three components: a randomized controlled trial, embedded qualitative study and a survey investigating pathways of care. The randomized controlled trial will compare ongoing low molecular weight heparin treatment for cancer-associated thrombosis versus cessation of low molecular weight heparin at six months treatment (current licensed practice) in patients with locally advanced or metastatic cancer. The embedded qualitative study will include focus groups with clinicians to investigate attitudes to recruiting to the study, identify the challenges of progressing to a full randomized controlled trial, and also semi-structured interviews with patients and relatives/carers to explore their attitudes towards participating in the study and potential barriers and concerns to participation. Finally, a UK wide survey exercise will be undertaken to develop a classification and enumeration system for the cancer associated thrombosis models and pathways of care. DISCUSSION There is a lack of evidence determining the length of anticoagulation for patients with cancer associated thrombosis and subsequently treatment length varies. The ALICAT study will consider the feasibility of recruiting patients to a phase three trial. TRIAL REGISTRATION Current Controlled Trials ISRCTN37913976.