Prevalence and patterns of symptomatic thromboembolism in oncohematology.

BACKGROUND AND OBJECTIVE Approximately 15% of patients with cancer will experience a thrombotic episode at some time. Some patients are at particularly high risk depending on the histology of the malignant disease. The aim of the study was to determine the actual prevalence of thrombotic episodes in oncohematologic patients. DESIGN AND METHODS We conducted a retrospective cohort analysis on a total of 515 patients that were admitted to the out-patients clinic (Institute of Medical Semeiotics) from January 1, 1986 to January 31, 1996. Two main groups were selected for this study: 133 patients suffering from a myeloproliferative disorder and 382 patients affected by a lymphoproliferative disorder. Follow-up lasted a median of 33 months in both groups (range 3-144 months). The difference between the observed events for each group was estimated by the odds ratio and chi square. Age and sex distribution were estimated by the Mann-Whitney test. Distribution of overall survival was estimated by the Kaplan-Meier method and compared between groups (DVT patients and non DVT patients) by the log-rank test. RESULTS Twenty-three patients experienced a venous thrombotic disorder. The prevalence of deep vein thrombosis (DVT) in myeloproliferative and lymphoproliferative disorders was 8.27% (n = 11) and 3.14% (n = 12) respectively (odds ratio = 0.36; 95% CI = 0.14-0.90; chi-square = 4.94 p = 0.028). DVT was apparently idiopathic in 17 cases. In 4 patients another cancer was present; in the remaining 2 patients the thrombotic episode was associated with other predisposing factors. Although 7 of the 23 patients with DVT died, we cannot find any difference in the overall survival compared to oncohematologic patients who did not experience DVT. INTERPRETATION AND CONCLUSIONS The prevalence of symptomatic DVT in the oncohematological patients is lower than reported for solid tumor. Patients affected by myeloproliferative disease have a higher risk of developing thrombosis. DVT if well-treated does not influence the survival of oncohematological patients.