Physicians should manage comorbidities in older long-term breast cancer survivors and their cancer-free counterparts the same, according to a study published in the January issue of the American Journal of Managed Care. The results showed the risk of cardiovascular disease was similar in both groups.

Reina Haque, PhD, MPH, of Kaiser Permanente Southern California in Pasadena, and colleagues wanted to examine whether older breast cancer survivors were at greater risk of cardiovascular disease compared with the general population and if excess risk was due to differences in comorbidities.

“Because few older breast cancer survivors are treated with chemotherapy, particularly those agents known to be cardiotoxic, examining the impact of comorbidities on CVD [cardiovascular disease] risk is crucial,” they wrote. “Therefore, a well-characterized comparison group with long follow-up is essential to determine whether there truly is excess morbidity in older women treated for breast cancer.”

They used data from the BOWI and BOWII longitudinal studies, which were designed to assess the effectiveness of breast cancer treatments. Haque et al identified women who were 65 years old or older who were diagnosed with early stage breast cancer between 1990 and 1994 and were alive five years later. BOWII extended follow-up beyond 10 years and included a comparison group.  

They defined a cardiovascular disease event as a composite of MI, congestive heart failure, coronary artery disease, arrhythmias and cerebrovascular disease. They based their analysis on 1,361 matched pairs.

The mean follow-up was five years in the survivor group and 5.3 years in the comparator group. In the entire cohort, 46.5 percent of the women experienced a cardiovascular disease event (45.3 percent of survivors and 47.7 percent of comparators). The rates of the composite outcome also were similar.

The strongest predictors of a cardiovascular disease event were smoking history, diabetes and hypertension. They found similar results in an analysis that excluded women treated with chemotherapy.

“This study demonstrates that long-term prognosis in older breast cancer patients is affected by management of preexisting conditions, and these may be best managed by primary care providers,” Haque et al recommended. “Our results also suggest that management of comorbidities in survivors should not be different from that in the general population of older patients.”

BOW I and II were an HMO Cancer Research Network studies that incorporated data from integrated healthcare systems. Consequently results may not be applicable to the broader population.

For more on cancer and cardiovascular disease, read “Surviving Cancer, but at a Cost: Radiation & Chemo-induced Cardiovascular Diseases.”