Lack of association between venous thrombosis and subsequent malignancy in a retrospective cohort study in young patients

Thromboembolism preceding cancer: a correlation study

Thromboembolic (TE) events preceding cancer have been observed. Some studies failed to find this correlation. We retrospectively examined the cancer incidence following thromboembolic events in patients at our medical center. Medical records of 183 patients with established thromboembolic events documented in their records were selected and reviewed. Time interval between primary, secondary, and recurrent TE events preceding cancer diagnosis was analyzed. Two hundred age- and sex-matched controls seen during the same period and without any evidence of TE were randomly selected and charts reviewed for malignancy. Cancer occurred after TE in 48 of 183 patients (26.2%). In controls, cancer was diagnosed in 23 (11.5%). This was statistically significant with an odds ratio of 2.736 (1.586, 4.720). In the 64 primary TE patients, the cancer incidence was 37.5%. The 63 patients with recurrent TE had an incidence of 35.4%, and 56 secondary TE patients had an incidence of 27.1%. Time between initial TE and cancer diagnosis was <6 months in 27 (56.3%) patients, between 6 months and 1 year in 12 (25.0%), 1-5 years in 5 (10.4%), and >5 years in 4 (8.3%). Fourteen (31.1%) TE patients presented with metastatic cancer. This study indicates that thromboembolic events are important predictors of cancer. Cancer in this population occurs within a year in the majority of patients. Cancer screening in patients without identifiable risk factors for thrombosis could be helpful for early detection, diagnosis, and management of cancer.

The hypercoagulable state of malignancy: pathogenesis and current debate

A hypercoagulable or prothrombotic state of malignancy occurs due to the ability of tumor cells to activate the coagulation system. It has been estimated that hypercoagulation accounts for a significant percentage of mortality and morbidity in cancer patients. Prothrombotic factors in cancer include the ability of tumor cells to produce and secrete procoagulant/fibrinolytic substances and inflammatory cytokines, and the physical interaction between tumor cell and blood (monocytes, platelets, neutrophils) or vascular cells. Other mechanisms of thrombus promotion in malignancy include nonspecific factors such as the generation of acute phase reactants and necrosis (i.e., inflammation), abnormal protein metabolism (i.e., paraproteinemia), and hemodynamic compromise (i.e., stasis). In addition, anticancer therapy (i.e., surgery/chemotherapy/hormone therapy) may significantly increase the risk of thromboembolic events by similar mechanisms, e.g., procoagulant release, endothelial damage, or stimulation of tissue factor production by host cells. However, not all of the mechanisms for the production of a hypercoagulable state of cancer are entirely understood. In this review, we attempt to describe what is currently accepted about the pathophysiology of the hypercoagulable state of cancer. We also discuss whether or not to screen patients with idiopathic deep venous thrombosis for an underlying malignancy, and whether this would be beneficial to patients. It is hoped that a better understanding of these mechanisms will ultimately lead to the development of more targeted treatment to prevent thromboembolic complications in cancer patients. It is also hoped that antithrombotic strategies may also have a positive effect on the process of tumor growth and dissemination.

Venous thromboembolism and occult malignancy

Trousseau is considered to be the first to have recognised a relation between venous thromboembolism (VTE) and malignancy. Illtyd James and Matheson in 1935 were the first in the Anglo-Saxon literature, at least to our knowledge, to report the observation of a patient with occult cancer at time of his venous thrombosis. Meanwhile, cancer has become an established risk factor for VTE. The prevalence of concomitant cancer in patients presenting with VTE varies considerably between the studies due to differences in, for instance, threshold of suspicion, screening methods, and characteristics of the patients like age. A consistent observation is the low prevalence of concomitant cancer in patients with secondary thrombosis, comparable to the prevalence in the general population. A 3-19-fold increase in prevalence of concomitant cancer has been reported in patients presenting with an idiopathic VTE. The same applies for occult cancer in patients with secondary and idiopathic VTE. The prevalence of occult cancer in patients with secondary VTE is comparable with the prevalence of cancer in the general population, while the prevalence of occult cancer in patients with idiopathic VTE is 4-10%. It seems possible to detect a substantial number of additional cancer patients, at time of diagnosis of idiopathic VTE, by means of extensive screening. However, results of randomised trials, evaluating the effect on survival rate, are lacking.