Venous Thrombosis and Breast Cancer in Older Women: Racial Disparity in Risk Factors and Outcomes

Introduction: Racial differences in thrombotic risk factors in women with breast cancer are not known. The aim of the study was to determine the prevalence of venous thrombosis in older white and black women with breast cancer and to evaluate the risk factors and outcomes associated with venous thrombosis by race.

Materials & Methods: For this population based cohort study, the Surveillance, Epidemiology, and End Results (SEER) data, capturing 28% of US population, and linked to the Medicare inpatient database were used for women 65 years and older diagnosed with breast cancer. Venous thrombosis (VTE) was defined as a diagnosis of either deep vein thrombosis (DVT) or pulmonary embolism (PE) or both. Demographic characteristics, diagnoses of comorbidities and size, stage, grade and receptor status of breast cancer were the covariates extracted from the database.

The chi-square (χ²) test was used to compare frequency distributions for categorical variables. Logistic regression analysis was used to examine the unadjusted and adjusted ORs with 95% CIs for thrombotic risk factors and for mortality associated with VTE in women with breast cancer stratified by race.

Results: There were 251,945 white and 24,083 black women 65 years and older diagnosed with breast cancer from 2000 to 2011 in the SEER-Medicare database. 6.4% white and 10.1% black women (p < 0.001) with breast cancer had a diagnosis of VTE, including DVT (4.9% vs. 7.9%, p < 0.001) and PE (2.8% vs. 4.3%, p < 0.001). In unadjusted analysis, statistically significant odds ratios were similar in white and black women with some variations for demographic factors, characteristics of cancer and all comorbidities other than sickle cell disease which was associated with increased risk of VTE in black women only.

In white women with breast cancer, adjusted analysis demonstrated that VTE was associated with advancing age (76-80 years: OR=1.31, 95% CI, 1.08-1.58 and over 80 years: OR=1.39, 95% CI, 1.16-1.66), distant metastasis (OR=2.58, 95% CI, 1.57-4.24), hypertension (OR=3.00, 95% CI, 2.54-3.52), heart failure (OR=1.77, 95% CI, 1.50-2.08), liver disease (OR=1.64, 95% CI, 1.09-2.46), kidney disease (OR=1.62, 95% CI, 1.35-1.94), COPD (OR=1.49, 95% CI, 1.23-1.80), hyperlipidemia (OR=1.46, 95% CI, 1.27-1.68) and myocardial infarction (OR=1.42, 95% CI, 1.13-1.79). In black women with breast cancer, hypertension (OR=3.22, 95% CI, 2.05-5.04), heart failure (OR=2.08, 95% CI, 1.40-3.10) and hyperlipidemia (OR=1.79, 95% CI, 1.26-2.54) were the risk factors associated with VTE. The size, grade and receptor status of the breast cancer were not associated with VTE risk in either white or black women after adjustment for other risk factors.

Higher proportions of both white and black women with breast cancer had less than a 12 month survival with VTE compared to those without VTE (white women: 9.9% vs. 7.5%, p < 0.001 ; black women: 14.7% vs. 10.9%, p < 0.001). Mortality was higher in black women than in white women (71% vs. 65%, p < 0.001) with VTE but after adjusting for risk factors, VTE conferred a higher risk of death in white women (OR=1.78, 95% CI, 1.52-2.08) than in black women (OR=1.63, 95% CI, 1.09-2.42).

Conclusion: The study identified differences in thrombotic risk factors and risk of death associated with VTE between older white and black women with breast cancer. This may help to stratify the risk of individual patients and develop targeted prevention and management strategies for older women with breast cancer.