Disparities in Breast Cancer Mortality Between Rural and Urban Patients Projected to Widen by 2035

Lower income, advanced stage of disease, and treatment differences were biggest contributors to the higher rates of breast cancer death among rural patients

ATLANTA – Between 1999 and 2020, breast cancer mortality declined across rural and urban populations, but by 2005, mortality among rural patients surpassed that of urban patients and after 2013 remained consistently higher, a disparity that is projected to widen further by 2035, according to research presented at the 19th AACR Conference on The Science of Cancer Health Disparities, held October 18-21 in Atlanta.

“Breast cancer is a major cause of cancer-related death in the United States, and patients living in rural areas face a particularly high risk of dying from the disease,” said presenter Nickolas Stabellini, MD, PhD, who is a postdoctoral scholar at Case Western Reserve University and University Hospitals Seidman Cancer Center.

“Rural patients may have greater difficulty obtaining screening, accessing timely diagnostic testing, seeing specialists, or traveling repeatedly for treatment,” he said. “These challenges may contribute to later-stage diagnosis, differences in treatment receipt, and, ultimately, differences in breast cancer outcomes.”

While the disparity in breast cancer mortality between rural and urban patients has been well documented, Stabellini noted that it remains unclear how this disparity is evolving and which factors may be most influential. “If we want to address this disparity and improve outcomes, we need to understand where the trends are heading and which contributing factors are most important,” he said. “Identifying how these differences arise can help guide interventions aimed at reducing disparities in breast cancer mortality.”

To determine how the differences in breast cancer mortality between rural and urban populations have changed—and to identify the main factors underlying the disparity between the groups—Stabellini and colleagues analyzed patient data from the past two decades using two separate nationwide datasets: the Centers for Disease Control and Prevention (CDC) WONDER database to examine how breast cancer mortality changed in rural and urban populations between 1999 and 2020; and the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) database to understand the contributions of different socioeconomic and clinical factors to breast cancer mortality.

Among the 1,156,445 breast cancer deaths included in the CDC WONDER database, 189,586 occurred in rural patients, and 966,859 occurred in urban patients. After adjusting for age, breast cancer mortality was found to decline between 1999 and 2020 in both rural and urban populations. However, the decline occurred more slowly in the rural population, which led to the breast cancer mortality among rural patients surpassing that of urban patients in 2005. After fluctuating in subsequent years, the breast cancer mortality among rural patients became consistently higher beginning in 2013, reaching a rate 7% higher than that of urban populations by 2020. This translated to 32.51 vs. 30.48 deaths per 100,000 among rural and urban patients, respectively, in 2020.

Based on these data, the researchers projected that the rural-urban disparity in breast cancer mortality would continue to widen through 2035, when the age-adjusted breast cancer mortality rate in rural populations is expected to be about 13% higher than in urban populations.

“In 2020, age-adjusted breast cancer mortality was about 2 deaths per 100,000 women higher in rural than urban populations. If the trends observed in our study continue without major changes, this difference is projected to increase to about 3.8 deaths per 100,000 by 2035, equivalent to approximately 38 more breast cancer deaths per 1 million women in rural compared with urban populations,” Stabellini explained.

To determine the contributions of different socioeconomic and clinical factors to the higher mortality among rural patients, the researchers used data from SEER of 688,165 patients diagnosed with breast cancer between 2000 and 2020, 10.2% of whom resided in rural areas. Those living in rural areas had a 21% higher risk of breast-cancer related death than patients in urban areas before accounting for potential contributing factors. After adjusting for a combination of factors—age at diagnosis, race, ethnicity, tumor stage at diagnosis, breast cancer molecular subtype, receipt of chemotherapy, and receipt of radiotherapy—rural patients in this dataset still had a 3% higher risk of breast cancer-related death than urban patients.

Adjusting for various socioeconomic, demographic, and clinical factors individually revealed that the main contributors to the higher breast cancer mortality among rural patients were county-level income (accounting for 45.3% of the excess deaths), advanced stage at diagnoses (24.9%), radiation omission (11.4%), and chemotherapy omission (7.9%). Race/ethnicity was not found to contribute to the rural-urban disparity in breast cancer mortality.

“Although breast cancer mortality has declined overall in the United States, our findings underscore that this progress has not been shared equally between rural and urban communities,” said Stabellini. “The reduction in breast cancer mortality has occurred more slowly in rural communities, contributing to persistent rural-urban disparities. Our study provides updated information on these trends and goes a step further by examining the patient and community factors that may help explain the difference.

“The disparities we observed appear to be linked, at least in part, to socioeconomic conditions, stage at diagnosis, and differences in treatment. This is important because several of these factors may be modifiable,” he added.

Based on the findings, Stabellini suggested that addressing financial barriers and improving health care access may be especially impactful. “These factors are interconnected, so reducing the observed disparity will likely require interventions at several points along a patient’s cancer journey rather than a single solution,” he said.

A limitation of the study was that it was an observational study, which means that the researchers could not prove causal relationships. Further, county-level income data may not reflect each patient’s individual circumstances, and some demographic and clinical factors were not captured by the SEER database.

The study was supported by the researchers’ institutions. Stabellini reports no conflicts of interest.

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