Long Term Treatment and Prevention Of Recurrent VTE In Cancer Patients: Results Of The Canadian Proact Survey
Authors: Blais Normand , Butts Charles A. , Crowther Mark A. , Cox-Kennett Nanette , Martineau Josée 
Published: October 2019

Abstract

Introduction
Cancer associated thrombosis (CAT) is the second leading cause of death in cancer patients after death from cancer. Despite multiple available guidelines for CAT management, there remains variability in treatment practices. In order to gain insight on this variability in Canada, a survey was conducted to identify the perceived importance of managing CAT, identify differences in the pharmacological management of CAT, highlight the main barriers to optimal extended treatment and prevention of recurrent venous thromboembolism (VTE), outline challenges associated with long term treatment adherence, and identify predictors of patient non-adherence.

Methods
A survey was designed targeting physicians involved in the management of CAT. The questionnaire included queries on physician practice, 37 items related to beliefs and attitudes about extended treatment for prevention of recurrence of VTE, and a 30-item patient-specific profile.

Results
Responses were obtained from 21 professionals from four Canadian provinces (Nova Scotia, Quebec, Ontario, and Alberta); 76% were hematologists and/or oncologists, 14% were internists and 10% were pharmacists. Community and academic centers were well represented. Specific management profiles were obtained for 131 patients. Most care givers felt that VTE recurrence was an important issue deserving extended therapy for most patients. Although more than 90% believed bleeding and recurrent VTE risk should influence the length of treatment, only 62% believe that VTE recurrence risk should modify the type of treatment and 52% were concerned of the risk of bleeding with long term therapy (≥6 months). 71% of respondents believed patients’ lack of awareness of the risk of recurrent VTE reduces adherence to anticoagulant therapy for extended treatment of VTE. Although 100% of respondents detailed giving verbal patient counseling, only 19% provided written information to patients. 95% stated they assessed compliance verbally; less than 20% used more objective measures (pharmacy records, laboratory monitoring). Participants admitted to using results of clinical trials (95%) more than clinical guidelines (48%) as most felt that the published guidelines contained conflicting recommendations. The main drivers of treatment choice were clinical evidence, efficacy, and personal experience. No respondents indicated they preferred to use oral anticoagulants for extended therapy of CAT and 43% believed that LMWHs should not be used interchangeably. Most (95%) stated they follow-up with patients directly to reassess therapy after 3-6 months of treatment. The patient profile information showed the median age of patients was 62 years and 60% were female. Lung cancer, colon cancer, breast cancer, and lymphoma were the most common tumor sites and accounted for 50% of described cases. Cases of deep vein thrombosis (DVT) and pulmonary embolism (PE) were evenly represented and 82% were symptomatic. Most events were temporally related to cancer therapy (69%), presence of a central venous catheter (18%), and recent surgery (17%). Less than 5% of these cases presented with a contraindication to anticoagulation therapy (severe thrombocytopenia, active bleeding) at CAT diagnosis. Most patients were treated in the outpatient setting. Nonetheless, hospitalization was required in 33% of cases with an average patient stay of 10.8 days. Hospitalized patients were preferentially treated with LMWH (84%) and usually stayed on the same regimen upon discharge (8.3 ± 6.4 months). Long term treatment was largely managed with LMWHs (most frequently dalteparin – 80% of all treated patients) while few were managed with vitamin K antagonists (6%) or novel direct antithrombotics (2%). Anticoagulant therapy for outpatients was prescribed for 9.0 ± 7.7 months after the most recent VTE episode.

Conclusion
In Canada, CAT is believed to be an important complication of cancer. Extended therapy is indicated for most patients with CAT. Although bleeding risk is perceived as an important reason to modify therapy, contraindications to LMWHs were rare in the reported cases. Uptake of outpatient therapy of CAT is widespread in this country, yet hospitalization is still frequently required at diagnosis and is associated with prolonged inpatient stays. Even if non-adherence to antithrombotic therapy was believed to be rare among patients with CAT, this was rarely rigorously monitored.

Disclosures:
Blais: Pfizer: Consultancy; Sanofi: Consultancy; Leo: Consultancy. Butts:Pfizer: Consultancy, Honoraria, Speakers Bureau. Crowther:Pfizer: Consultancy, Honoraria, Research Funding; Octapharma: Consultancy, Membership on an entity’s Board of Directors or advisory committees; Merck: Consultancy; Leo Pharma: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau; CSL Behring: Speakers Bureau; Boehringer Ingelheim: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees; Baxter: Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Asahi Kasai: Membership on an entity’s Board of Directors or advisory committees; Sanofi-Aventis: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Viropharma: Membership on an entity’s Board of Directors or advisory committees. Cox-Kennett:Pfizer: honorarium as a speaker Other. Martineau:Pfizer: honorarium as a speaker Other; Boehringer: honorarium as a speaker, honorarium as a speaker Other; Bayer: honorarium as a speaker, honorarium as a speaker Other; Sanofi: honorarium as a speaker and participated in clinical trial, honorarium as a speaker and participated in clinical trial Other; BMS: honorarium as a speaker Other.