Asymptomatic venous thrombosis in cancer patients--a problem often overlooked. Results of a retrospective and prospective study.

BACKGROUND: Venous thrombosis with and without pulmonary embolism is a frequent complication of malignancies and second among the causes of death in tumour patients. Its incidence is reported to be 10 to 15%. Since for methodological reasons, this rate can be assumed to be too low and to disregard asymptomatic venous thrombosis, a combined retrospective and prospective study was performed to examine the actual frequency of venous thrombosis in tumour patients. PATIENTS AND METHODS: The histories of 409 patients (175 women, 234 men, mean age 69 years [19 to 96 years]) with different tumours, consecutively enrolled in the order of their altogether 426 inpatient treatments, were checked in retrospect for the frequency of venous thrombosis and pulmonary embolism. Subsequently, 97 tumour inpatients (36 women, 61 men, mean age 70 years [42 to 90 years]) were systematically screened, by means of duplex sonography and/or venography, for venous thromboses in the veins of the pelvis and both legs.
RESULTS: In the retrospective analysis, where no systematic screening for thromboses was performed and only symptomatic thrombosis was recorded, venous thrombosis was found in 6.6% of all tumour patients, whereas in the prospective examination with systematic duplex sonography and / or venography of all patients, the percentage was 33%. In the prospective study, 31.3% of venous thromboses were symptomatic and 68.7% asymptomatic. In 39.3% of the cases in the retrospective analysis and 25% in the prospective analysis, venous thrombosis occurred during chemotherapy, surgery or radiation therapy. Venous thrombosis was most often seen in metastasizing tumours and in colorectal carcinoma (40%), haematological system diseases (28.6%), gastric cancer (30%), bronchial, pancreas and ovarian carcinoma (28.6%), and carcinoma of the prostate (16.7%).
CONCLUSION: Regular screening for thrombosis is indicated even in asymptomatic tumour patients because asymptomatic venous thrombosis is frequent, can lead to pulmonary embolism and has to be treated like symptomatic venous thrombosis. This is particularly true for metastasization during chemotherapy, surgical interventions, or radiation.