DEAR MAYO CLINIC: Why is it that some breast cancers have higher survival rates than others?
ANSWER: The main reason for the difference in survival rates is that breast cancer is not just one disease. It is well accepted that there are four distinct molecular categories of breast cancer. However, new data suggests that there are additional distinct subsets of breast cancer. These subsets have unique characteristics that can influence the long-term outlook associated with each of them.
The most common molecular subset of breast cancer is characterized by its ability to respond to the female hormone estrogen. This type of cancer is characterized by the presence of estrogen receptors. If a tumor is estrogen receptor (ER) positive, that means the breast cancer cells contain receptors that bind to estrogen. Women and men with ER-positive breast cancer tend to have an initial lower risk of the cancer coming back after breast surgery compared with women whose tumors do not have estrogen receptors (known as ER-negative breast cancer).