Mortality risk analysis of asymptomatic and symptomatic venous thromboembolism in patients with metastatic colorectal cancer

Background: The current study aimed to compare the clinicopathological characteristics and survival data of the patients with metastatic colorectal cancer who had symptomatic or asymptomatic venous thromboembolism (VTE) and non-VTE. Patients and Methods: The files of the patients diagnosed with 521 metastatic colorectal cancer in our hospital between April 2001 and January 2015 were analyzed retrospectively. VTE was divided into four groups in relation with their locations as extremity, port, visceral, and nonvisceral VTE. VTE was also categorized as symptomatic or asymptomatic in relation with the presence of thrombus-related symptoms. The median overall survival was considered as the period from the diagnosis of metastasis to death or last control. Results: A total of 424 patients were included in the study. The median age was 62 (range 24-95) years. Seventy-two (16.9%) patients developed VTE. Among all, 8.9% of the patients had asymptomatic VTE, 8% of them had symptomatic VTE, and remaining 83.1% of them were in the non-VTE group. Visceral thrombosis located in pulmonary and the thrombosis located in extremities and port location was usually symptomatic while nonvisceral thrombosis and nonpulmonary visceral thrombosis were frequently asymptomatic and found incidentally on radiological imaging obtained for tumor. Anticoagulant treatment was administered to all patients with symptomatic thrombosis. None of the patients with asymptomatic thrombosis was given anticoagulants. The median survival was 16.3 months (95% confidence interval [CI]: 13.8-18.9) in symptomatic, 22.5 months (95% CI: 18.6-26.4) in asymptomatic, and 21 months ( 95% CI: 20.5-21.5) in the non-VTE groups (P = 0.03). Conclusions: Symptomatic VTE is a predictor of poor survival in patients with metastatic colorectal cancer. The presence of an asymptomatic thrombus does not have any effect on prognosis, and follow-up without anticoagulant treatment may be appropriate in those patients.