CLINICAL AND PATHOLOGICAL ASPECTS ASSOCIATED WITH VENOUS THROMBOEMBOLIC EVENTS IN PATIENTS WITH SOLID TUMORS: A CASE-CONTROL STUDY

Introduction: Venous thromboembolism (VTE) has a high incidence in cancer patients, being a cause of significant morbidity and mortality in this group. Several factors are associated with a higher risk of thrombotic events, which may be related to the patient, cancer or even the treatments used. OBJECTIVES: To comparatively evaluate demographic, histopathological and clinical aspects in patients with solid tumors who had or did not have VTE. To assess possible factors associated with venous thromboembolic events. To analyze the characteristics of the venous thromboembolic events. Methods: This is an observational, retrospective, etiological, case-control, unpaired study. Were selected patients diagnosed with cancer between 2014 and 2019 and treated at a public service of reference in oncology. Cases were defined as patients diagnosed with VTE (outcome) and controls as those without thrombotic events. Exposure was defined as receiving a specific oncological treatment (chemotherapy, endocrine therapy, radiotherapy or surgery). Clinically relevant variables were selected for univariate analysis (age, sex, disease staging, tumor sites according to Khorana score, specific oncological treatment, known thrombogenic treatments) and potential confounders were added for multivariate analysis. Results: 91 patients were included in the case group and 182 in the control group (1:2). Both groups were similar in terms of demographic, histopathological and clinical characteristics, but the case group had a higher mortality rate (30.8% versus 15.9%, p=0.04). In univariate analysis, advanced staging was associated with a higher risk of VTE (OR 1,85; CI 95% 1,043,30; p=0,036) and treatment with hormone therapy was a protective factor (OR 0,41; CI 95% 0,21-0,82; p=0,010). After adding confounding factors, multivariate analyzes maintained endocrine therapy associated with a lower risk of VTE (OR 0.18; 95% CI 0.07-0.47; p=0.000 and OR 0.41; 95% CI 0.20- 0.86; p=0.018), without identifying risk factors. Hospitalization (35.2%) and surgery (23.1%) were the main risk factors present in the three months preceding the events. Lower extremity deep venous thrombosis (DVT) occurred in 54.9% of cases and pulmonary embolism (PE) in 37.4%. Conclusion: In the present study, hormone therapy was a protective factor for VTE, possibly because patients with indication for endocrine therapy have initial or controlled metastatic disease, with a lower risk for venous thromboembolic events.