Making Advances for MBC Through Epidemiology 

We support epidemiological research – the study of how often diseases occur in different groups, and why – to understand how we can best advocate for people living with MBC.

Alliance Analyses of Epidemiological Data

Informed by a landscape report in 2014 that identified a lack of data about the population of people living with MBC across the U.S. the Alliance has supported four research articles that explore key questions about metastatic breast cancer. Read the summary.

How many women are living with MBC?

In partnership with the National Cancer Institute (NCI), our article “Estimation of the Number of Women Living with Metastatic Breast Cancer in the United States” estimated that, as of 2020, there were more than 168,000 women living with MBC in the U.S. Read the article.

What are survival rates for MBC?

Working with data from a dedicated institutional breast cancer registry with long-term follow-up on patients, our article Differential Presentation and Survival of De Novo & Recurrent Metastatic Breast Cancer Over Time: 1990-2010 reported higher survival rates for de novo patients than for those who experienced a recurrence. Read the article.

How have recurrence & survival rates changed?

Again using data from a dedicated institutional breast cancer registry, our article Examination of a paradox: recurrent metastatic breast cancer incidence decline without improved distant disease survival: 1990-2011 found that while incidence of recurrent MBC declined over time, there has been a shift to  more  triple-negative MBC. Read the article.

How do regional differences in access and treatment affect outcomes?

Comparing data from the previous institutional breast cancer registry with the regional SEER database, our article Metastatic Breast Cancer Survival Improvement Restricted by Regional Disparity: Surveillance, Epidemiology, and End Results and Institutional Analysis: 1990 to 2011 concluded that access and treatment approaches will need to be identified and adopted in order to achieve equitable outcomes. Read the article.

Gaps in Understanding MBC

A comprehensive 2014 landscape report identified key areas where researchers must increase their understanding of metastatic breast cancer.

In the past few decades, survival rates after MBC diagnosis have increased only by months, not years, with hospital-based studies generally reporting a larger benefit than population-based studies.

This modest increase has been observed mainly in ER+ (estrogen receptor positive/hormone sensitive) and/or HER2+ (human epidermal growth factor receptor 2–positive) metastatic breast cancer due to the wide use of targeted therapies. No survival benefit has been found in triple-negative metastatic breast cancer.

The disparity in survival between Black and non-Hispanic white women appears to be increasing. It is unclear how much of the disparity is related to access to care and socioeconomic concerns, and how much is related to the greater incidence of triple-negative metastatic breast cancer in Black women.

The prevalence and incidence of patients with metastatic breast cancer is unknown. Also unknown is whether the number of relapsed metastatic breast cancer patients is increasing, decreasing, or staying the same. Without this information, we cannot accurately and effectively demonstrate the need for services or plan and fund the application of services.

Disease trajectories, outcomes, and patient experiences for different subtypes of metastatic breast cancer have not been well characterized.

Critical questions regarding the optimal treatment of MBC remain unresolved. It is imperative that the use, effectiveness, and impact of treatments on the overall MBC population be understood.

Despite existing research, we have no accurate estimate of how long MBC patients are likely to live, and factors underlying variability in median survival across studies are unknown. Potential factors could include differences in access to newer drugs, targeted therapies and multiple lines of treatment; differences in access to careful follow-up and expert palliative care to preserve optimal quality of life; and the presence of comorbidities.

Research demonstrates poorer outcomes for disadvantaged, underinsured populations overall. But we do not know the true impact of socioeconomic factors on treatments and care and how this may affect survival rates and quality of life for MBC patients.

Better data is needed on the number of early stage breast cancer patients who experience a recurrence and metastasis, and on outcomes and length of survival after a metastatic diagnosis. Only very modest improvements in survival after a metastatic diagnosis have been observed, and not in all populations.

Help accelerate research on metastatic breast cancer by joining our interactive patient experience registry, MBC Connect. Or learn how you can support our work by becoming an Alliance member.