Department of Research & Evaluation News

Early detection and screening of breast cancer has allowed most women to thrive long after their diagnosis. However, women of color persistently experience disparities in outcomes. Researchers at the Kaiser Permanente Southern California Department of Research & Evaluation have been working to find ways to reduce these disparities and improve the survival rates for all women with breast cancer.

Their most recent research found that the risk of death among women with metastatic breast cancer increases with increasing numbers of chronic conditions, such as diabetes, hypertension, and obesity. The study was published Oct. 4, 2022,   in Cancer Epidemiology, Biomarkers & Prevention.

“Focusing on managing chronic medical conditions in metastatic breast cancer patients may also help reduce disparities in all-cause and breast cancer-related mortality,” said the senior author, Reina Haque, PhD, of the Kaiser Permanente Southern California Department of Research & Evaluation and the Kaiser Permanente Bernard J. Tyson School of Medicine, both in Pasadena, Calif.

Early-stage breast cancer is highly survivable, with 5-year survival rates near 99%. Given the high screening rates and advances in treatment, when diagnosed at an early stage, breast cancer can be managed like a chronic condition. However, there is much room for improvement in the 5-year survival rate among women with metastatic breast cancer, which is only 29%, Dr. Haque said.

The research study included nearly 1,000 diverse women diagnosed with late stage IV metastatic breast cancer between January 2009 and December 2017. Almost half of the patients in the study were women of color, which is important for many reasons including because women of color tend to be diagnosed at later stages of breast cancer than white women.

• Of the 995 women in the cohort, 52% were non-Hispanic white; 14% were African American/Black; 20% were Latina; 11% were Asian/Pacific Islander; and 3% were other/mixed/Native American.
• Nearly 17% of the cohort had diabetes and 45% had hypertension.
• Overall, 644 deaths occurred in the cohort (median follow-up time of 1.8 years), of which 88% were related to breast cancer.
• The risk of overall mortality was increased in Asian/Pacific Islander and African American/Black women when compared to white women AFTER adjusting for the effects of co-morbidities.
• Overall, women with 1 or more comorbidities had more than 3-fold higher overall mortality rate than those without any comorbidities. Similar associations were found for breast cancer-specific mortality.
  • Also, the more comorbidities, the greater the risk of death.

“We hypothesized that having chronic health conditions like diabetes increases the risk of death after breast cancer diagnosis because such patients might be less likely to receive aggressive cancer treatments or their overall health status might have contributed to the risk,” said the study’s lead author, Lauren P. Wallner, PhD, formerly of the Kaiser Permanente Southern California Department of Research & Evaluation, and now at the University of Michigan. “However, this association varied by race/ethnic group. “This observation was strongly seen among Asian/Pacific Islander women and African American/Black women.”

Dr. Haque said this research was important because patients with metastatic breast cancer are a very understudied group, and studies that also include diverse women even more rare.

“At Kaiser Permanente Southern California, we are uniquely positioned to study outcomes in people of color given our diverse patient population,” Dr. Haque said. “With advances in treatment, many women are living longer with metastatic breast cancer, but that survival benefit is not being realized equally across racial/ethnic groups. We were glad to have the opportunity to use research to get a glimpse into this issue and identify potential ways to mitigate those differences.”

In addition to Dr. Wallner and Dr. Haque, other authors of the research include Lie H. Chen, DrPH, of the Department of Research & Evaluation; Tiffany A. Hogan, MD, of the Kaiser Permanente Los Angeles Medical Center; and Farah M. Brasfield, MD, of the Kaiser Permanente Anaheim Medical Center.

This study was funded by Kaiser Permanente Southern California, with additional support from the National Institutes of Health/NHLBI.