Exploring Rural Disparities in Breast Cancer Mortality

Institution: Humboldt State University Sponsored Programs Foundation
Investigator(s): Terry Uyeki, M.S. - Brenda Elvine-Kreis, M.A. -
Award Cycle: 2014 (Cycle 20) Grant #: 20AB-1600 Award: $217,102
Award Type: CRC Pilot Award
Research Priorities
Community Impact of Breast Cancer>Disparities: eliminating the unequal burden of breast cancer



Final Report (2020)

Previous research has suggested that Humboldt County’s age-adjusted mortality rate for breast cancer is among the highest in the state of California. This community-based participatory research study investigated two research questions: 1) What factors are associated with higher breast cancer mortality in Humboldt County? 2) How does the survival of women with breast cancer in Humboldt County compare to women in the rest of California, and with women who live in urban areas or rural areas? California Cancer Registry (CCR) data from 1990 - 2010 was analyzed in conjunction with 2000 U.S. Census population data to calculate age-adjusted incidence and incidence-related mortality rates for female breast cancer in California and Humboldt County, as well as for cases in rural and urban areas of the state. This study is the first time breast cancer deaths in California have been examined based on population density. CCR data was also analyzed to explore factors which might explain disparities in breast cancer survival within Humboldt County and among rural and urban areas in the state. Two outcome variables were examined: death from breast cancer and 5-year survival.

Medical and demographic variables were examined in order to describe the population of women at higher risk. Four factors – age, stage at diagnosis, tumor grade, and marital status—were found to be associated with poorer 5-year breast cancer survival in women in Humboldt County, as well as for women in the rest of California, though Humboldt County women who were 65 years or older, diagnosed at late stage, had grade 3 tumors, or were unmarried at diagnosis, had slightly poorer probability of 5-year survival from breast cancer, compared to their counterparts in the rest of the state.

The first three factors (age, stage and grade) are well-established as being related to poorer cancer survival. Marital status has been reported by others as being associated with cancer survival, suggesting that married cancer patients may have better survival than unmarried patients due to social support, rather than due to economic advantages (Lin Gomez, et al., 2016). No significant differences in breast cancer survival were found due to location by Medical Study Service Area, or race or ethnicity, though it could be due to Humboldt County’s small population, which is also predominantly non-Hispanic White.

Humboldt County’s average 21-year death rate for female breast cancer was higher than death rates for women with breast cancer in the rest of the state, but the difference was relatively small (26 women per 100,000 in Humboldt County compared to 22.8 women per 100,000 in the rest of California). The study also found that breast cancer death rates for women in rural areas of the state were similar to those of women with breast cancer in urban areas (~23 women per 100,000), yet lower compared to Humboldt County. The finding that the average breast cancer death rates and survival rates for rural and urban populations were so similar was unexpected. Findings also suggest that the higher death rate in Humboldt County cannot be simply attributed to more women being diagnosed at late stage, or more women being diagnosed with higher grade cancer. Proportionately fewer women in Humboldt County were diagnosed at late stage breast cancer or at grade 3 breast cancer, compared to other areas in the state.

A Community Advisory Council of 11 members representing breast health advocates and health care met regularly to advise on the study implementation, analysis, results translation, and dissemination. Seven community forums were held in the county, attended by almost 100 people. Two of the five community liaisons that were hired represented the Native American and Latino communities. A Hmong community liaison was not hired due to smaller population numbers, thus a Hmong community forum was not held as originally planned. Reader-friendly summaries of study findings in English and Spanish, a summary of community forum outcomes and community input, Frequently Asked Questions, and links to the community partner’s breast health resources are available on a website, www.rbcss.org.

Future directions for research suggested by community members include developing a prospective study to follow patients with breast cancer through diagnosis and treatment in order to gather information on additional factors that may contribute to the higher breast cancer mortality rate in Humboldt County. This would allow us to gain insight into the role factors that were not available in the CCR database may play in breast cancer survival. Another area suggested as a result of the current study is an analysis of factors related to breast cancer survival rates in FAR (Frontier and Remote) vs non-FAR areas of the state.