The Incidence of Deep Vein Thrombosis in Breast Cancer Patients Receiving Outpatient Cancer Therapy in Iran

Background: Venous thromboembolism (VTE) is one of the main causes of mortality in patients with cancer. This study was conducted to assess the incidence of deep vein thrombosis (DVT) in breast cancer patients receiving outpatient cancer therapy. Materials and Methods: This multi-center prospective cohort study was conducted on patients with breast cancer, initiating an outpatient chemotherapy regimen in five medical centers in Iran. Eligible patients were enrolled in the study consecutively between January 2013 and January 2015. The primary outcome was lower extremity DVT based on duplex/doppler ultrasonography two months after the first course of chemotherapy (visit 2) and after the end of the course (visit 3). All patients were followed-up from the onset of chemotherapy until the first occurrence of lower extremity DVT, death, or the end of the course. Results: A total of 427 eligible breast cancer patients were recruited in the study, 403 of whom attended at least one follow-up visit. The mean (SD) duration of follow-up was 4 (1.3) months. During the follow-up, only one patient showed DVT on duplex/doppler ultrasonography in visit 2. Therefore, the two-month and overall cumulative incidence risk of DVT was 0.25% (95% CI: 0.00–0.74%). However, the mean D-dimer level showed no significant change (P>0.05). Conclusion: Our findings showed the low risk of DVT in breast cancer patients receiving outpatient cancer therapy.