ORLANDO – Women diagnosed with localized breast cancer while in their 70s have a higher mortality from cardiovascular disease than from their breast cancer, according to new data from the Women’s Health Initiative.
“Identification and treatment of cardiovascular disease risk factors among older women with breast cancer will likely improve survivorship and should be a high priority, especially for older women with incident localized breast cancer,” Na-Jin Park, Ph.D., said at the American Heart Association scientific sessions.
Na-Jin Park, Ph.D.
She presented an analysis that included 101,916 women who were free of cardiovascular disease and breast cancer upon enrollment in the Women’s Health Initiative (WHI) at age 50-79 years during 1993-1998. During follow-up in this prospective cohort study, 4,340 of them developed invasive breast cancer. The diagnosis occurred an average of 5 years into the study, and patients were followed for 10 years afterwards. “Forty-one percent of women with breast cancer already had cardiovascular risk factors at baseline, way before their breast cancer diagnosis,” noted Dr. Park of the University of Pittsburgh.
Among women diagnosed with breast cancer in their 50s, 40% of all deaths were from breast cancer and 15% were caused by cardiovascular disease. In contrast, the cumulative impact of atherosclerosis was far more prominent in women diagnosed with breast cancer at a more advanced age. Indeed, among women diagnosed with breast cancer in their 70s, about 15% of deaths were caused by breast cancer, while 25% resulted from cardiovascular disease.
The number of baseline cardiovascular risk factors present at enrollment in the WHI turned out to be a powerful determinant of the likelihood of acute MI or death as a result of coronary heart disease in participants who developed breast cancer.
Of the 4,340 women who later developed invasive breast cancer, 2,562 were free of hypertension, diabetes, and hypercholesterolemia and were nonsmokers upon enrollment. In an age-adjusted analysis in which this risk factor–free group served as the reference population, the risk of MI after breast cancer diagnosis was increased 1.65-fold in those with a single baseline risk factor, 3.2-fold in those with two, and 5.8-fold in women with three cardiovascular risk factors. Similarly, the breast cancer patients’ risk of CHD death climbed stepwise by 1.78-, 2.28-, and 3.6-fold as the number of baseline cardiovascular risk factors increased from one to three.
The greatest risk was seen in breast cancer patients who at WHI enrollment were current smokers with an additional cardiovascular risk factor. They had a 9.6-fold greater risk of an acute MI after developing breast cancer, compared with breast cancer patients with none of the baseline cardiovascular risk factors. They also had a 7.7-fold increased risk of CHD death.
The WHI was funded by the National Heart, Lung, and Blood Institute. Dr. Park reported having no financial conflicts of interest.