Lifeboat Foundation

Nearly 270,000 people in the United States are diagnosed with breast cancer each year.

According to the Susan G. Komen Foundation, about 70%–80% of these individuals experience estrogen receptor-positive (ER+) breast cancer, where cancer cells need estrogen to grow. In terms of treatment, this presence of hormone receptors provides a nice handle for targeting tumors, say with therapies that knock out the tumor cell’s ability to bind to estrogen and prevent remaining breast cancer cells from growing.

However, even if treated successfully, on average, one in five individuals with ER+ breast cancer experience a late recurrence when dormant tumor cells in distant parts of the body, such as the bone marrow, reactivate anywhere from five to over 20 years after initial treatment.