Comorbid Conditions Threaten Breast Cancer Survivors

Leading Causes of Death Among Breast Cancer Patients Ages ≥66 by Age at Diagnosis and by Stage of Disease, 1992-2000

Breast cancer survivors age 66 and older are more likely to die of cardiovascular disease (CVD) than they are of the cancer itself, one indication of the significant role that comorbidities play in overall mortality, a new study indicates.

CVD was the primary cause of death for 15.9% of the survivors, followed closely by breast cancer at 15.1%, according to researchers from the Colorado School of Public Health at the University of Colorado in Aurora whose findings were published in Breast Cancer Research.

The study involved 63,566 women diagnosed with breast cancer between 1992 and 2000 whose histories were culled from the Surveillance, Epidemiology and End Results (SEER)-Medicare linked database. Of the group, 32,594 women (51.3%) had died through the end of 2005, when the study period ended.

Investigators found that factors associated with dying from causes other than breast cancer included older age, more advanced tumor stage, and comorbidities; factors characteristic of the breast cancer deaths included advanced tumor stage and grade, estrogen-receptor negative status, and comorbidities. The analysis included 19 comorbidities.

The data indicate that medical professionals should pay more attention to the risk of CVD and other comobidities among patients with breast cancer, the researchers said.

“Patient management rightfully focuses on cancer after diagnosis, but consideration of other existing comorbid conditions should also be integrated into patient management and recovery plans,” wrote lead author Jennifer L. Patnaik, PhD, of the department of epidemiology. “Especially among older breast cancer survivors, risk management of factors associated with CVD can help improve overall survival.”

Specifically, Patnaik noted the link between long-term cardiac toxicity and chemotherapy, and suggested the condition might be underdiagnosed and undertreated.

The research team said limitations of the study include the validity of cause of death coding, missing pieces of information, and billing code practices. Additionally, more than 33,000 eligible women were excluded from the study because they were enrolled in a Medicare HMO and their files were not available.

Patnaik JL, Byers T, DiGuiseppi C, Dabelea D, Denberg TD. Cardiovascular disease competes with breast cancer as the leading cause of death for older females diagnosed with breast cancer: a retrospective cohort study [published online ahead of print June 20, 2011]. Breast Cancer Res. 2011;13(3):R64. doi:10.1186/bcr2901.