Venous thromboembolism in cancer patients receiving neoadjuvant chemotherapy: a systematic review and meta-analysis

Essentials Cancer patients are at risk for venous thromboembolism (VTE). The risk of VTE in less advanced stage cancer on neoadjuvant chemotherapy is unclear. In over 7800 patients, we found a 7% pooled incidence of VTE during neoadjuvant therapy. Highest VTE rates were observed in patients with bladder and esophageal cancer. SUMMARY: Background Venous thromboembolism (VTE) is a frequent complication in cancer patients receiving adjuvant treatment. The risk of VTE during neoadjuvant chemo-radiotherapy remains unclear. Objectives This systematic review evaluated the incidence of VTE in patients with cancer receiving neoadjuvant treatment. Methods MEDLINE and EMBASE databases were searched from inception to October 2017. Search results were supplemented with screening of conference proceedings of the American Society of Clinical Oncology (2009-2016) and the International Society of Thrombosis and Haemostasis (2003-2016). Two review authors independently screened titles and abstracts, and extracted data onto standardized forms. Results Twenty-eight cohort studies (7827 cancer patients, range 11 to 1398) were included. Twenty-five had a retrospective design. Eighteen cohorts included patients with gastrointestinal cancer, representing over two-thirds of the whole study population (n = 6002, 78%). In total, 508 of 7768 patients were diagnosed with at least one VTE during neoadjuvant treatment, for a pooled VTE incidence of 7% (95% CI, 5% to 10%) in the absence of substantial between-study heterogeneity. Heterogeneity was not explained by site of cancer or study design characteristics. VTE presented as pulmonary embolism in 22% to 96% of cases (16 cohorts), and it was symptomatic in 22% to 100% of patients (11 cohorts). The highest VTE rates were observed in patients with bladder (10.6%) or esophageal (8.4%) cancer. Conclusions This review found a relatively high incidence of VTE in cancer patients receiving neoadjuvant therapy in the presence of some between-study variation, which deserves further evaluation in prospective studies.