Four years ago I wrote in Huffington Post about important gaps in our knowledge about the epidemiology of metastatic breast cancer ("Where is the Data? The Epidemiology of Metastatic Breast Cancer").
Until recently, we were missing important data about the epidemiology of metastatic breast cancer (MBC). We did not know how many people are living with metastatic breast cancer (MBC), how many early stage breast cancer patients have recurrences, and how the incidence and outcome of MBC have changed over time for the common subtypes of breast cancer.
Under the leadership of Musa Mayer, Shirley Mertz, and myself, the MBC Alliance partnered with staff scientists at the National Cancer Institute (NCI) Surveillance, Epidemiology, and End Results (SEER) program, and with academic scientists at the Swedish Cancer Institute (Seattle, WA), to answer these critical questions.
The MBC Alliance set out to develop the most accurate epidemiology information and statistics on the disease. Thanks to the hard work of NCI statisticians, today we have the best statistics on MBC currently available across the broad US population.
In 2017, a new study entitled “Estimation of the Number of Women Living with Metastatic Breast Cancer in the United States,” appeared in the journal Cancer Epidemiology, Biomarkers & Prevention. Led by our co-author Dr. Angela Mariotto (NCI), utilizing SEER registry data as well as modeling of recurrence rates, we estimated that as of Jan. 1, 2017, more than 150,000 women in the U.S. are living with MBC, 75% of whom have initially been diagnosed with an earlier stage of breast cancer and suffered a metastatic recurrence months to years later.
The study also found that median and five-year relative survival for women initially diagnosed with MBC is improving, especially among younger women. In our study, we were unable to make estimates for men diagnosed and living with MBC; which remains an unmet need for future studies.
Key metastatic breast cancer findings relevant to today
- As of January 2020, an estimated 168,000 women and men are living with MBC in the U.S.
- 75% of women living today with MBC were initially been diagnosed with early stage (stage I-III) breast cancer and suffered a metastatic recurrence.
- Despite the poor prognosis of MBC, survival of women initially diagnosed with MBC (de novo MBC) has been increasing, especially among young women.
Our study provides the most accurate information to estimate the number of women in the US currently living with MBC. The number of women living with MBC is increasing, and the study authors suggest that this is likely due to improvements in treatments that have extended survival for many patients. Our study further highlights the importance of documenting recurrence from early stage breast cancer and to foster more research into the specific needs of the MBC patient population.